TW200831682A - Cold work die steel, die, and method for production of cold work die steel - Google Patents

Abstract

Disclosed is a cold work die steel which comprises (by mass): C: 0.20-0.60%, Si: 0.5-2.00%, Mn: 0.1-2%, Cr: 3.00-9.00%, Al: 0.3-2.0%, Cu: 1.00-5%, Ni: 1.00-5%, Mo: 0.5-3% and/or W: 2% or less (including 0%), and S: 0.10% or less (excluding 0%) wherein these components satisfy the following requirements (1) to (3) [wherein each square bracket [ ] means a content (%) of each element]: (1) [Cr] x [C] ≤ 3.00; (2) [Cu]/[Ni]: 0.5-2.2; and (3) [Mo]+0.5 x [W]: 0.5-3.0%, with the remainder being iron and unavoidable impurities. Also disclosed is a die produced by using the steel. Further disclosed is a method for producing the cold work die steel.

Description

。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 Or a tool for forming a material for a mold used for punching (', bending, embossing, trimming, etc.) at a high temperature, and a method for manufacturing the mold steel. [Prior Art] For the forming of steel sheets for automobiles and steel sheets for home appliances, it is required to improve the life of the molds as the strength of the steel sheets increases. Especially for automotive steel sheets, because of the environmental problems, the fuel-saving performance of automobiles and the demand for high tensile strength of about 5 90 MPa or more are rapidly increasing, but it is accompanied by the early damage of the surface of the mold. A "biting phenomenon" occurs (a φ junction phenomenon occurs when the shape is formed), which causes a problem that the life of the mold is extremely shortened. The mold is composed of a mold base material (steel steel) and a surface hardened layer (surface film) applied thereto. The mold of the base metal is made of annealing and tempering by means of annealing and metal cutting (in this book, especially the quenching process is called melt processing; the tempering is called aging treatment). made. Steel for molds (steel for cold die casting) has been widely used in the past: JI SS KH 5 1 is a representative of high-C high-Cr alloy tool steel represented by JIS SKD1 1 and further improved wear resistance. The mold for punching the high-speed mold car uses the raised steel film to burn the surface, -- the case is treated with general mining; more tools -5 - 200831682 steel. These tool steels are mainly used for precipitation hardening of Cr-based carbides, Mo, W, and V-based carbides to improve hardness. In addition, based on the simultaneous improvement of the two properties of wear resistance and toughness, a low alloy tube speed tool steel in which the alloy contents of C, Mo, W, V, etc. in JIS SKH51 are reduced is also used. Called: matrix-hsis). In order to further improve the characteristics of the steel for cold working molds, for example, Patent Document 1 to Patent Document 3 propose a technique for improving the composition of steel. The solution disclosed in Patent Document 1 is intended to enhance the hardness of matrix-hsis (low alloy high speed tool steel) by suppressing the coarseness of crystal grains after high temperature quenching by containing a large amount of Nb and/or Ta. Therefore, it is possible to carry out high-temperature quenching to achieve high hardness (increased wear resistance). Patent Document 2 discloses a steel for cold die casting which can achieve dimensional deformation suppression characteristics and high hardness characteristics, and mainly discloses: (A) tempering due to decomposition of residual Worth iron during quenching The dimensional deformation at the time of deformation and the suppression of the dimensional deformation caused by the precipitation strengthening of the Ni-Al intermetallic compound cancel each other; (B) the size is further suppressed by using the segregation index K calculated from the specific steel component. Deformation. The first diagram of Patent Document 2 shows that the tempering treatment is performed at a temperature at which the maximum hardness can be obtained. Patent Document 3 discloses that an amount of Ni and A1 is added for the purpose of improving hardness by suppressing the dimensional change amount (size deformation) caused by the quenching and tempering treatment, in particular, suppressing the expansion dimensional deformation during tempering. -6- 200831682 A steel for cold die casting mold containing an appropriate amount of Cu corresponding to the Ni and A1 is added. Further, it has been revealed that the "biting resistance" can be improved by adjusting the content of C and Cr so that the carbide distribution in the metal structure is more finely dispersed. Further, Patent Document 4 discloses that, for the purpose of reducing the manufacturing cost of the mold, the conventional method of performing the quenching and tempering treatment after the cutting processing is first performed, but the cutting processing is performed from the quenching and tempering state (quenching back) Fire-cutting technology for "pre-hardened steel". Specifically, it is disclosed that the steel which can perform punching at normal temperature, which exhibits good machinability, is high in hardness, and in particular, the amount of C, Si, and S is controlled in an appropriate amount. Hardened steel. However, as far as the current situation is concerned, molds using pre-hardened steel have a short life span and have not reached the stage of practical use. In the above-mentioned Patent Documents 1 to 4, it is mainly disclosed that the dimensional deformation (size change) after heat treatment (after aging treatment or after tempering treatment) is suppressed by controlling the components in the steel, but Patent Documents 5 to 7, which will be described later, Mainly to reveal: a technique for controlling dimensional deformation by controlling heat treatment conditions such as quenching, tempering, and the like. Patent Document 5 therein discloses that: 1 50 to 4 50 are respectively implemented. (: A method of suppressing the dimensional change after quenching and tempering at a low temperature tempering and a high temperature tempering of 4 8 〇 5 5 5 ° C. Patent Document 6 discloses: performing quenching - 0 to -20 (TC low temperature treatment - low temperature tempering method below 500 ° C. In detail, it is revealed that the temperature change is controlled by low temperature treatment at the above temperature to adjust the amount of residual Worth 200831682 field iron, Next, a method of low-temperature tempering to achieve a target size is disclosed. Patent Document 7 discloses that the quenching property is improved by adjusting the composition of the steel, and the quenching property of the iron is controlled, and quenching is performed by gas cooling. In order to achieve the hardness required for the mold, it is possible to reduce the hardness required for the mold and to reduce the deformation after the heat treatment. [Patent Document 1] Japanese Patent Laid-Open No. Hei 1 0-3 3 0 894 [Patent Document 2] Japanese Laid-Open Patent Publication No. Hei. No. 2006-169624 (Patent Document 4) JP-A-2002-241 894 (Patent Document 5) [Patent Document 6] Japanese Laid-Open Patent Publication No. 2001-172748 (Patent Document 7) JP-A-2002-167644 [Summary of the Invention] [Problems to be Solved by the Invention] Requirements for Steel for Cold Working Dies In addition to the above-mentioned high hardness and high dimensionality, and excellent dimensional deformation inhibition after heat treatment, it is also excellent in weld repairability. The so-called "welding repair" mainly involves welding the mold. The damage (in detail, the flaw, the unevenness of the surface hardened layer, etc.) is corrected and repaired, and is performed for the purpose of recycling the mold, for example, thickening by argon welding which has been widely used at present. Welding, etc. As mentioned above, because the increase in the tensile strength of high tensile steel of about 580 MPa or more is required to increase the life of the mold, the mold life is extremely reduced. In order to reduce the cost, it is necessary to frequently apply to the mold. Perform welding repair work. However, if welding repair is performed on a mold having a hardened film, the difference in hardness around the welded portion The degree becomes large, and it becomes prone to cracking and biting. In particular, it will appear clearly: softening of the Heat Affected Zone (HAZ) after welding (HAZ softening), therefore, the life of the mold after welding repair This reduction in the situation will cause problems. The AZ softening phenomenon occurs in a region slightly away from the fusion portion (the boundary between the weld metal and the base metal, also called the "welding melting line"), in which heating is performed. The temperature is lower than that of the fusion part, because it is transferred from the fine grain of the Worthite iron, so the hardenability is reduced, and the proportion of the soft ferrite iron phase is increased, and it is farther away from the fusion part. It is in a state of high temperature tempering, so it is considered to be a decrease in hardness. Fig. 1(a) is a view showing a state in which the base materials are welded to each other by a weld metal, and Fig. 1(b) is a view showing the hardness distribution of the A region shown in Fig. 1(a). As shown in Fig. 1(b), the hardness of the HAZ decreases and becomes softer as it moves away from the fusion portion. When the HAZ is softened, even if the surface hardening treatment is carried out later, the surface hardening layer cannot be sufficiently protected, and the surface hardened layer is quickly damaged, thereby reducing the life of the mold. Further, the welding repairing operation is carried out as described above except that the surface hardening film is applied to the base material, and is also performed before the base material is applied as the surface hardening film. In particular, when a high-tensile steel sheet having a tensile strength of about 590 MPa or more is formed by press molding using a mold, it is difficult to press a shape that matches the desired shape. Therefore, sometimes the test press and the weld repair are performed in advance - 9-200831682 ( Thickening the weld) to get the shape you want. In the trial press process, after the weld repair is performed, the press forming is performed without performing the heat treatment, so that the flaw is easily generated in the HAZ softened portion. This enthalpy which occurs in the softening portion of the ΗAZ also remains on the surface film formed by the hardening treatment to be carried out later. Therefore, such a residual portion is considered to be a starting point for damage of the film. In addition, it occurs not only in the softening portion but also in the hardened portion (refer to Figs. 1 and 7), and cracks and notches are likely to occur in the hardened portion, which causes problems. Therefore, the industry does not expect anyone to provide a mold steel which can suppress the softening of the weld at the time of welding repair and can easily carry out the thick welding of the corner portion and has excellent weld repairability. However, the aforementioned patent literature does not make any consideration for solder repairability, so the reduction in mold life after solder repair is the problem. The present invention has been made in view of the above circumstances, and an object thereof is to provide a steel for cold working die and a mold which have high hardness and excellent dimensional deformation suppression after heat treatment. Further, another object of the present invention is to provide a method for producing a steel for cold working mold which has high hardness and excellent dimensional deformation inhibition after heat treatment. [Means for Solving the Problem] That is, the present invention relates to the following inventions of 1 to 12. -10- 200831682 1. In terms of mass %, it conforms to C: 〇·20 ～0.60%, s i : 0 · 5 ～2.0 0 %, Μ η : 〇 . 1 〜 2 %,

Cr * 3.00 ~ 9.00%, A1 : 〇 · 3 ~ 2.0%, C u : 1 · 0 0 〜 5 %, • Ni : 1 · 〇〇, ~5%, Μ 〇: 〇· 5~3 % and / Or W: 2% or less (including 〇%), S ·· 〇. 1 〇% or less (excluding 〇%), the following formula (1) to (3) {[] represents the content of each element (%) Meaning) Equation (1) [Cr]X[C]€ 3.00, Equation (2) [Cu]/[Ni]: 0.5~2'2, Equation (3) [Μ〇]+ 〇· 5χ[W]: 〇·5 to 3.0% φ of the required parts, the rest is iron and steel for cold working molds with unavoidable impurities. 2. The steel for cold working die according to the above 1, which contains V: 0.5% or less (excluding 〇%). 3. Further containing at least one element selected from the group consisting of 1^, 2^, 1^, 丁3, and >^, which is 0.5% or less (excluding 0%) of the above 1 or 2 Steel for cold working die. 4. The steel for cold working die according to any one of the above 1 to 3, which has a Co: 10% or less (excluding 0%). -11 - 200831682 5. The transition point of Mastite iron (Ms point) expressed by the following formula: Ms point = 550-361x [C] -39χ[ Μη]-35χ[ V]-2〇Χ[ Cr -7x[Ni]-10x[Cu]-5χ([Mo]+[W]) + 1 5x[ Co]+ 30x[ A1] {] in the formula represents the content (%) of each element The steel for cold working die according to any one of the above 1 to 4, which is 170 ° C or higher. 6. A mold obtained by using the steel for cold working die according to any one of the above 1 to 5. A method for producing a steel for cold working mold, which is directed to a steel according to the composition described in the above 1, further comprising: preparing a quantity corresponding to the following formula (4): wherein the [] represents the content of each element ( %) (5) [Cu]/[C]: a steel step of the requirements of 4.0 to 15; and a process of performing melt treatment and aging treatment under the conditions of the following formula (5) , ΤΑ-1 0 ^ T2 ^ TA + 1 〇...(5 ) In the formula (5), TA = 0.29xTl-2.63x [ Cu ] /[ C]+ 225, τ 1 is the melting temperature (°C ), T2 system aging temperature (°C). 8. The steel system contains the production method described in the above 7 of V: 0.5% or less (excluding 〇%). -12· 200831682 9. The steel system contains at least one element selected from the group consisting of Ti, Zr, Hf, Ta, and Nb, which is 〇·5 % or less (excluding 0%) of the above 7 or The manufacturing method described in 8. 10. The steel system according to any one of the above 7 to 9 wherein Co: 10% or less (excluding 〇%) is contained. 11. The transition point of the methadrite iron (MS point) expressed by the following formula φ Ms point = 550-361x [C] -39x [Mn] -35x [V] -20x [Cr] -17x [Ni] -10x [Cu]-5x ( [Mo] + [ W )) + 1 5x [ Co ] + 30x [ A1 ] The production method according to any one of the above 7 to 10 of 170 ° C or higher is the above-mentioned A mold obtained by the production method according to any one of 7 to 11. [Effect of the Invention] The steel for cold working die of the present invention has a high hardness and excellent dimensional deformation inhibition after heat treatment, and has excellent weld repairability, as described above. Therefore, the mold obtained by using the above-described steel for cold working die is particularly suitable for a molding die for a high tensile steel sheet having a tensile strength of about 5 90 MPa or more, which can further improve the life life, especially after welding repair. Further, in the production method of the present invention, the conditions in the steel and the conditions for the timely treatment of the melt treatment-13-200831682 are appropriately controlled, so that it can be efficiently produced: high hardness, excellent heat treatment Steel for cold working die with dimensional deformation inhibition. Therefore, the mold obtained by using the production method of the present invention is particularly suitable for a molding die for a high-tensile steel sheet having a tensile strength of about 590 Å or more, which can further improve the life, especially after welding repair. life. [Embodiment] [Best Mode for Carrying Out the Invention] Hereinafter, the present invention will be described in detail. Further, the percentages in the present specification are based on mass unless otherwise specified. In addition, all percentages defined by mass are the same as all percentages defined by weight. First, the steel for cold working die according to the first aspect of the present invention will be described in detail. In order to provide the steel for cold working die which has characteristics such as hardness, dimensional deformation inhibition after heat treatment, and weld repairability, the inventors of the present invention are required to provide the steel for cold working die. First, the use of a conventional JIS SKD 1 1 and matrix-hsis (low alloy high speed tool steel) mold was used to investigate the cause of the "biting phenomenon" caused by damage to the surface film of the mold. Fig. 2(a) is an optical micrograph showing the state in which the surface of the mold after the film of TiN is applied to the mold steel using Jis SKD1 1 as a mold steel; Fig. 2 (b) And Fig. 2 (c - 14 - 200831682) is a part of the enlarged optical microscope photograph. For the sake of providing, 'Fig. 2(d) is an optical micrograph of the mold before applying the film of TiN. In Fig. 2(d), what appears to be white is Cr-based carbide. From Fig. 2(b) and Fig. 2(c), in the region where the film has been peeled off, hard coarse Cr-based carbon (mainly a carbide containing about 1 to 50 // m of Cr and Fe) In the above-mentioned observation, the inventors of the present invention have thought that the origin of the (biting phenomenon) is the above-mentioned coarse Cr-based carbide. It is only possible to suppress the formation of the carbide (do not let it be formed), thereby preventing the peeling of the surface film and improving the life of the mold. Based on the above-mentioned novelty, the present inventors have further continually added. As a result, it has been found that if it is desired to suppress the formation of coarse carbides and to improve the above-described characteristics, it is extremely important to appropriately control the amount of C, and to actively add various alloy components and appropriately control the composition of the alloy. of. In detail, it is found that in order to obtain the characteristics to be treated, it is not the conventional method of controlling the increase in hardness of the carbide, but actively adding the alloy composition (especially Cu, Ni, Mo, W). It is effective to obtain hardness by precipitation hardening of alloying elements, and it is mainly possible to use the precipitation hardening of Al-Ni-based intermetallicization, and the carbonization by Mo or W and C. Transcend, and continued to carry out the results of the experiment, completed the components of the present invention. In this specification, the term "high hardness" means that after the reference material is found, the material can be inspected after the crack is formed, and the design is expected to be A1. -15-200831682 The method described in the examples is intended to measure the maximum hardness, and the maximum hardness is 65 0 HV or more. In the first aspect of the present invention, the "size deformation (dimension change rate) after heat treatment" means that when the thickness, the width, and the length of the aging treatment are measured in three directions, the average enthalpy and the maximum enthalpy are measured. Evaluate with the smallest difference between the two. For the sake of explanation, the former is referred to as "average 尺寸 of the dimensional deformation rate", and the latter is referred to as "the difference of the dimensional deformation rate". In the first aspect of the present invention, the "size 变形 of the dimensional deformation rate" and the "difference of the dimensional deformation rate" are used to evaluate the dimensional deformation after the heat treatment. The technique of Patent Document 2 in which the former (average 尺寸 of the dimensional deformation ratio) is measured is different. According to the results of experiments by the inventors of the present invention, if it is desired to sufficiently suppress the dimensional deformation after the heat treatment, it is not sufficient to reduce the average enthalpy of the dimensional deformation ratio by the method of Patent Document 2, and the thickness is not sufficient. It is indispensable to reduce the dimensional deformation (degree of difference) in all directions of the width and the length. For example, according to the experimental results of the present inventors, it is known that even the average deformation rate is suppressed.値, but sometimes the difference in the dimensional deformation rate is large (there is also the opposite case) (please refer to the example described later). In the first aspect of the present invention, the "size deformation after heat treatment is small (having excellent dimensional deformation inhibition property)" means that the heat treatment is measured according to the method described in the column of the examples to be described later. When the size changes before and after, the average 値 of the dimensional deformation rate is within the range of ±0.05%, and the difference in the dimensional deformation ratio 0 is 0.08% or less -16-200831682 In addition, in the present specification, "welding repairability" The HAZ softening amplitude is used for comparison. The term "excellent weld repairability" means a method in which the HAZ softening width is measured within the range of 6.5 mm or less when the method described in the following examples is used. The composition of the steel according to the first aspect of the present invention is not limited to the content of various alloying elements which contribute to precipitation hardening in a predetermined range, and is the following formula (1) to (3). The φ is also appropriately controlled by the balance between the predetermined elements and the like, thereby improving the above characteristics. As shown in the later-described embodiment, if one of the requirements of these requirements is not met, the desired characteristics cannot be ensured. In particular, in the present invention, it is indispensable to add all of Cu, Ni, and A1, for example, the components of the above-mentioned Patent Document 1 and Patent Document 3 which do not contain one of the three elements. Steel, the fact that the desired effect cannot be obtained, has been confirmed by experiments (please refer to the examples described later). In the steel according to the first aspect of the present invention, the "welding repairability" (measured by the ΗAZ softening range) and the "after heat treatment" are based on the main improvement target of the first aspect of the present invention. The relationship between the dimensional deformation inhibition property (the difference between the dimensional deformation rate in the longitudinal direction and the dimensional deformation ratio) is roughly as follows. First, if you want to improve the weld repairability (so that the softening width of the crucible is small), the upper limit of the [Cr]X[C], the Ms point (lower limit), the C amount (lower limit), the A1 amount (lower limit), and Ni. Quantity (lower limit), [ -17- 200831682

Cu]/[Ni] (upper limit, lower limit), [Mo]+0.5x [W] limit), and the amount of V (upper limit) are appropriately controlled, that is, as the HAZ softening amplitude is made small Designing the pointer and using the hardening caused by the formation of the granulated iron, but in addition to the low C of the C amount of about 0.2 to 0.6 0%, the addition of the alloy is mainly Al, Cu, Ni, Mo, Precipitation hardening due to W): ε-Cu, Ni-Al intermetallic compound, Ni-Mo intermetallicization. These precipitates are finely integrated and precipitated in the matrix, so the hardness is remarkably increased. In particular, Cu, Ni, and A1 are important precipitation hardening elements, and are elements which greatly inhibit the softening of HAZ. From the experimental results, it was confirmed that the steel in which one element of these elements was not substantially added could not achieve the desired HAZ softening inhibition effect. Further, it is known that the ratio of [Cu] / [Ni] (the ratio of [Cu) to [the ratio" is closely related to the suppression of HAZ softening, and by appropriately controlling the above ratio, HAZ softening can be suppressed. Fig. 6 is a graph showing the influence of the ratio of [Cu] / [Ni] on the HAZ softening width when the HAZ softening width is measured by the method described in the examples below, which is No. 7 of Table 3 to be described later. 8, 10, Table 4, No 35, and 37 results are shown in the chart. As shown in Fig. 6, it is known that the ratio of [Cu]/[Ni] is closely related to the HAZ softening range, and by controlling the above ratio within the range of 0.5 to 2.2, the HAZ softening amplitude can be suppressed. Within the scope of the invention (6.5mm (the lower. is not the inhibition points (such as the degree of the compound will already be, and Ni) cut out. This • 3 1 ~ can be closed to the following -18- 200831682 In addition, If it is desired to reduce the dimensional deformation after heat treatment as much as possible, it is mainly appropriate to control the product of the content of Cr and C (the upper limit of [Cr]x[C]), the amount of C (upper limit), and the amount of Si (upper limit). , Μ η amount (upper limit), Ms point (lower limit), A1 amount (upper limit), Ni amount (upper limit), Cr amount (upper limit), [Mo] + 0.5x [W] (upper limit) are important. In the present invention, the low C is essential, and therefore the Ms point becomes high. The generation of the original residual Worth iron amount is small, and the content of the alloy composition such as Cu, Ni, and A1 is appropriately controlled, so that it is obvious Suppression, especially after aging treatment at about 400~5 50 °C, table Shrinkage after surface hardening treatment. This is considered to be: by the addition of the above alloy composition, for example, in the low temperature range of about 400 to 500 ° C, mainly ε-Cu is formed, at about 45 〇 to 53 〇 ° In the intermediate temperature range of C, mainly Ni-(A1, Mo)-based intermetallic compounds are formed, and in the high temperature region of about 50,000 to 55 ° C, mainly Mo-V-based carbides are formed, and these precipitates are formed. The crystal structure (FCC structure) is different from the matrix (BCC structure), so the volume shrinks, which is helpful for suppressing dimensional deformation after heat treatment. Moreover, the composition of the present invention is designed to: do not precipitate coarsely Since the Cr-based carbide is considered to have a crystal structure in which direction is uniform, it is possible to effectively suppress dimensional deformation after heat treatment even in the production of a mold having a large-complex shape. The steel component of the first aspect of the present invention C: 0.20 - 0.60% C is an element which can ensure hardness and wear resistance, and is also useful for suppressing HAZ softening range -19-200831682. Further, if it is by CVD method In the mold When a carbide film such as VC or TiC is formed on the surface of the material, if the C concentration is too low, the thickness of the film is reduced. In view of such a problem, the above effects are effectively exerted. The lower limit of the amount of C is selected to be 0.20%. The amount of C is preferably 0.22% or more. However, if the addition is excessive, the residual Worthite iron will increase, and if the high temperature aging treatment is not performed, the expected result will not be obtained. The hardness is increased after the aging treatment, so that the dimensional deformation becomes large, so the upper limit is selected to be 0.60%. The amount of C is preferably 0.50% or less, more preferably 0.45% or less. S i : 0.5 ～2.0 0 %

Si is a deoxidizing element that is useful in steel making, and is an element that contributes to the improvement of hardness and ensuring machinability. Further, Si is also useful for suppressing the temper softening of the matrix of the loose iron of the matrix and suppressing the softening amplitude of the HAZ. In order to make this effect, the lower limit of the amount of Si was selected to be 0.5%. However, if an excessive amount is added, the segregation will become large, and not only the dimensional deformation after heat treatment becomes large, but also the toughness is lowered, so the upper limit is selected to be 2.00%. The lower limit of the amount of Si is preferably 1%, more preferably 1.2%, and the upper limit of the amount of Si is preferably 1.85%. Μ η : 〇· 1 ～2 % Μη is an element useful for ensuring hardenability. However, if the addition is excessive, the M s point will be significantly lowered, and the residual Worth iron will increase, so if high temperature aging treatment is not performed If you do not, you will not get the expected hard -20- 200831682 degrees. For these reasons, the content of Μη is selected. The lower limit of the amount of Μη is preferably 0.15%, and the I of the amount of Μη is preferably 0.5%, more preferably 0.35%.

Cr : 3.0 0 ~ 9.00%

Cr is an element useful for ensuring a predetermined hardness. When Cr 3.0 is 0%, the hardenability is insufficient, and the localized toughened iron is lowered, and the wear resistance cannot be ensured. It is more preferable that the amount of Cr is 3.5% or more. However, when excessively added, coarse Cr-based carbon is formed in a large amount, and shrinks after heat treatment, and the durability of the film is lowered to the upper limit of 9.00%. The amount of Cr is preferably 7.0% or less, more preferably 6.0% or less. A1 : 0 · 3 〜 2.0 % A1 is an element necessary for improving the hardness due to precipitation strengthening of Al-Ni-based gold such as Ni3Al. The HAZ softening range is also helpful. Further, A1 can also take these factors as a concern, and the lower limit of A1 is selected to be 0 · 3 %. In the case of the amount, the segregation will become larger, and not only the dimensional change after the heat treatment is the difference in the dimensional deformation rate, but also the toughness, which will result in the upper limit of 2.0%. The amount of A1 is preferably 0.50% or more, more preferably 0.7% or more and 1.6% or less.

Cu : 1.0 0 〜5 % The above range is 1%. If the amount is less than the hardness, the hardness will be 4.0%, so 6.5% will be combined with the oxidant. Test, added over (especially reduced, because 8 % or less is -21 - 200831682

Cu is an element necessary for improving the hardness due to precipitation strengthening of ε_Cu, and is also useful for suppressing the HAZ softening range. However, if the addition is excessive, the forging crack is likely to occur, so the upper limit is selected to be 5%. The amount of Cu is preferably 2.0% or more and 4.0% or less. N i : 1 · 0 0 ～5 %

Ni is an element necessary for improving the hardness by precipitation strengthening of an Al-Ni-based intermetallic compound such as Ni3Al, and is also useful for suppressing the softening range of ΗAZ. Further, Ni can be used together with Cu to suppress thermal brittleness due to excessive addition of Cu, and to prevent cracking during forging. However, if the addition is excessive, the residual Worthite iron will increase. If the aging treatment is not performed at a high temperature, not only the predetermined hardness will be ensured, but also the heat will be expanded. The amount of Ni is preferably 1.5% or more and 4.0% or less.

Mo : 0.5 to 3% and/or W: 2% or less (including 〇%)

Both Mo and W can form a Ni3Mo-based intermetallic compound in addition to the M6C-type carbide, and are elements which contribute to precipitation strengthening. However, if Mo and W are excessively added, the above-mentioned carbides and the like are excessively formed, and in addition to the decrease in toughness, the dimensional deformation after heat treatment (especially the difference in dimensional deformation ratio) becomes large, and thus is set in The above range. In the present invention, Mo is an essential component, and W is an element which can be selectively added, but these two elements can also be used at the same time. Mo is preferably 0.5% or more and 3% or less, more preferably 0.7% or more and 2.5% or less. Further, W is 2% or less -22- 200831682 is preferable, and 1 % or less is more preferable. S : 0.10% or less (excluding 〇%)

s is an element useful for ensuring machinability, but if it is excessively added, a weld crack will occur, so the upper limit is selected to be 0. i 0 %. The amount of S is preferably 0.07% or less, more preferably 〇·5% or less, and more preferably 25% or less. Further, the first aspect of the present invention must conform to the following formulas (1) to (3): The piece { 〔 } is the meaning of the content (%) of each element. Formula (1) [Cr]X[C]€ 3.00 The above formula (1) is set for the purpose of suppressing the formation of coarse Cr-based carbides, and the product of [Cr] and [C] exceeds 3.00. In the case of 'the dimensional deformation after heat treatment, the durability of the surface film is lowered. The product of [Cr] and [C] is preferably ΐ·8〇 or less, and 17〇 or less is more preferable. Further, 'the lower limit is based on the viewpoint of suppressing the suppression of the dimensional deformation after the heat treatment,' although it is preferably small, but considering that it is intended to effectively exert the above-described effects due to the addition of Cr and C, the 槪 is 0.8. It is appropriate. Formula (2) [Cu]/[Ni]: 0·5 ～2·2 The above formula (2) is mainly set as a parameter for suppressing the softening width of ΗAZ by precipitation strengthening of ε-Cu (please refer to the following) Example). In order to effectively exert this effect, the ratio of [Cu] to [Ni] was selected to be 0.5 to 200831682. However, if the above ratio becomes larger, forging cracks will occur, so the upper limit is selected to be 2.2. The above ratio is preferably 0.7 or more and 1.5 or less, more preferably 0.85 or more and 1.2 or less. (3) [ Mo ] + 0.5x [ W ] : 0.5 〜3·0% The Mo and W systems constituting the above formula (3) are elements which are helpful for precipitation strengthening as described above, and the above formula (3) It is mainly set as a parameter for ensuring the hardness increase due to precipitation strengthening of these elements, and is also effective for suppressing the HAZ softening range. In the above formula (3), the coefficient (0.5) of [W] is selected in consideration of a factor that the atomic weight of Mo is about 1 /2 of W. In order to effectively exert these effects, the lower limit of the above formula (3) is selected to be 0.5%. However, if the amount of Μ 〇 and W is excessively added, the above-mentioned carbides are excessively added, and in addition to causing a decrease in the directionality, the dimensional deformation after heat treatment (especially the difference in dimensional deformation rate) will become large, so The upper limit of the above formula (3) is selected to be 3.0%. The lower limit of the above formula (3) is preferably 1.0%, more preferably 1-2%, and the upper limit is preferably 2.8%. The composition of the steel of the first aspect of the present invention is as described above, and the remainder is iron and unavoidable impurities. As for the unavoidable impurities, for example, elements which are inevitably mixed in the manufacturing process, etc., such as elements such as ρ, Ν, Ο, etc., can be cited. The amount of sputum is preferably 0.05% or less, and 〇. 〇 3% is better. The amount of sputum is preferably less than 305 ppm, more preferably less than 200 ppm, and preferably less than 150 ppm. The amount of sputum is preferably 5 〇ρριη, more preferably 3 0 p p m or less, and 2 0 p p m or less. Further, the present invention can also add -24 - 200831682 to the following components for the purpose of improving other characteristics. V: 0.5% or less (excluding 0%) V is a carbide which can form a VC and is useful for improving the hardness and is an effective element for suppressing the HAZ softening range. Further, when the nitriding treatment such as gas nitriding, salt bath nitriding, or plasma nitriding is performed on the surface of the base material to form a diffusion hardened layer, it is an element effective for improving the surface hardness and increasing the depth of the hardened layer. If it is desired to effectively exert such a function, the amount of V is preferably 0.05% or more. However, if the addition is excessive, the amount of solid solution C will decrease, which will result in a decrease in the hardness of the parent phase, which is the structure of the granulated iron structure. Therefore, the upper limit is preferably set at 0.5%. The amount of V is preferably 0.4% or less, and more preferably 0.30% or less. At least one element selected from the group consisting of Ti, Zr, Hf, Ta, and Nb is 0.5% or less (excluding 0%), and these elements are all nitride forming elements for the nitride and A1N. An element that contributes to the improvement of toughness caused by fine dispersion and grain refinement. In order to effectively perform such a function, it is preferable to add Ti to 0.01% or more, Zr to 0.02% or more, Hf to 0.04% or more, Ta to 0.04% or more, and Nb to 0.02% or more. However, if the amount of addition is excessive, the amount of solid solution C is lowered, and the hardness of the granulated iron is lowered. Therefore, the total amount of the above elements is preferably 0.5%. The total amount of the above elements is preferably 0.4% or less, and more preferably 0. 30% or less. Further, the above elements may be added singly or in combination of two or more. -25- 200831682 C ο : 1 0 % or less (excluding 〇 % )

Co is an effective element for increasing the Ms point and reducing the residual Worth Iron, which can be used to increase the hardness. If you want to effectively play this role, it is advisable to add more than 1% of C. However, if the addition is excessive, the cost and the like will increase, and it is preferable to set the upper limit at 10%. The upper limit of the amount of Co is better at 5.5%. Ma Tian loose iron transition point (M s point) g 1 70 °C Ms point = 550-361x [C]-39x [Mn]-35x [ V ] -20x [ Cr ] -17x [Ni]-l〇x [Cu]-5x([Mo]+ [ W ]) + 1 5 x [ C o ] + 3 0 x [ A1 ] {wherein, [] is the meaning of the content (%) of each element} In the invention, the Ms point is mainly used as an index for hardness and suppression of dimensional deformation after heat treatment. If the Ms point is less than 1 70 ° C, the residual Worth iron will increase, if high temperature aging treatment is not performed, The expected hardness will not be obtained and will cause expansion after heat treatment. The higher the Ms point, the better, the greater the 槪 is better than 23 0 °C, the best above 23 5 °C, and the best above 250 °C. In addition, the upper limit 値, based on the above-mentioned action, is not particularly limited, but considering the effect of the addition of the above-mentioned elements constituting the Ms point, etc., it is preferable to use 350 ° C. 320 ° C is better. Further, the present invention also encompasses a mold obtained by using the steel for a mold described above. The method for producing the mold is not particularly limited, and for example, after the steel is melted, it is subjected to hot forging and then annealed (for example, after 770-200831682 is held at about 70 ° C for 7 hours, The average cooling rate of 17 ° C / hr is cooled in the furnace to about 400 ° C, and then placed and cooled to soften it, and then rough-processed into a predetermined shape by cutting or the like, and then, about 950 ° The melt treatment is carried out at a temperature of 1150 ° C - an aging treatment of about 4 to 5 30 ° C is carried out to obtain a desired hardness. Next, a method of producing the steel for cold working die according to the second aspect of the present invention will be described in detail. In order to provide, among the various characteristics required for the steel for cold working molds, the inventors have improved the hardness, the dimensional deformation inhibition after heat treatment, and the weld repairability (the mold life when the mold is damaged by welding, etc.) Steel for cold working molds with characteristics such as characteristics) is continuously reviewed. As a result, it has finally been found that, as long as the components in the steel are appropriately controlled, it is possible to achieve the desired purpose (the first aspect of the present invention). After the first aspect of the present invention, the inventor In order to further particularly improve the dimensional deformation inhibition after heat treatment, it is further reviewed based on the composition of the steel disclosed in the prior application. As a result, it has been found that, by using the steel disclosed in the first aspect of the present invention and performing the melt treatment and the aging treatment under appropriate conditions, it is possible to efficiently obtain the size which can further suppress the heat treatment. Varying cold working die steel. That is, the manufacturing method disclosed in the second aspect of the present invention is characterized in that it is possible to efficiently manufacture a cold working mold which can further suppress the dimensional change after heat treatment among the ith aspect of the present invention. The preferred manufacturing conditions for steel -27-200831682. In detail, it is characterized in that the melt temperature and the aging temperature are defined by a parameter (the mass ratio of Cu to C) which is most helpful for the dimensional deformation inhibition after heat treatment. According to the manufacturing method disclosed in the second aspect of the present invention, the "two-stage two-stage tempering treatment" described in Patent Document 5 and the low-temperature treatment described in Patent Document 6 are not carried out. In the heat treatment of the present invention, the tempering treatment (aging treatment) can be carried out in the same manner as in the related art, and the cold-working mold steel which can suppress the dimensional change after the heat treatment can be obtained. Here, the reason for the development of the method for producing a steel for cold working die according to the first aspect of the present invention to the second aspect of the present invention will be described. The present inventors first explored the reason why the surface film of the mold was damaged and the seizure phenomenon occurred in a mold using JIS SKD1 1 and matrix-hsis (low alloy high speed tool steel). As a result, it has been found that in the field after the peeling of the film, a hard, coarse Cr-based carbide (a carbide mainly containing Cr and Fe of about 1 to 50 μm) is precipitated on the surface, and Cracking occurs with this carbide as a starting point. Based on the results described above, the present inventors have considered that the origin of the biting phenomenon is the above-described coarse Cr-based carbide, and it is possible to prevent the formation of the carbide as much as possible (not to generate it). The peeling of the surface film improves the life of the mold. Based on the above-mentioned novelty, the inventors further reviewed it. As a result, it is found that if it is desired to suppress the formation of coarse inhibitors and to improve the above-mentioned characteristics, in addition to appropriately controlling the amount of C, various alloy components are actively added -28-200831682, and the alloy composition is appropriately controlled. The design approach is extremely important. In detail, it was found that in order to obtain the desired characteristics, it is not the conventional method of controlling the carbide to increase the hardness, but to actively add the alloy component (especially A1 'Cu, Ni). Mo, W) is effective in order to increase the hardness due to precipitation hardening of alloying elements, mainly by precipitation hardening of Al-Ni-based intermetallic compounds, and when carbides are formed by Mo, W and C. In the case of secondary hardening, the idea of increasing the hardness can be achieved. What has been described above is that the reason for reaching the first aspect of the present invention is passed. Then, the inventors of the present invention have been able to easily obtain a cold working die having a more excellent dimensional deformation inhibition after heat treatment, as long as it is not necessary to carry out a special heat treatment, as long as the melt treatment and the aging treatment are carried out in the same manner as in the related art. The high-productivity manufacturing method of steel is further reviewed. As a result, it was found that when the above-described steel is used for the melt treatment and the aging treatment, as shown in the examples described later, the temperature of both of them (melt temperature and time-dependent temperature) is utilized. The relationship between the "mass ratio of Cu to C" which is most helpful for the dimensional deformation inhibition after heat treatment is well defined, and the desired effect can be achieved, and the second aspect of the present invention is completed. Kind of manufacturing method. Specifically, it is known that when the melt temperature (°C) is T1, the aging treatment temperature (°C) is T2, and the mass ratio of Cu to C is [Cu]/[C], in the following formula 0·29χΤ1-2·63χ[ Cu]/[ C]+ 225 When the number 値 is ΤΑ, as long as T2 meets the following formula (5 -29- 200831682 TA-10S T2S TA+ 1〇... In the range of (ie, TA ± 10 °C) for the melt treatment and the aging treatment, the average dimensional deformation rate and the maximum dimensional deformation rate after heat treatment (detailed in detail) can be obtained. Both of them are steels having extremely excellent dimensional deformation inhibition in the range disclosed in the second aspect of the present invention (refer to Table 7 of the examples). The "melting treatment" referred to in the present specification is In the same meaning as the tempering treatment, the term "aging treatment" has the same meaning as the tempering treatment. In the present specification, the term "high hardness" means that the hardness is measured according to the method described in the column of the examples described later. In the second aspect of the present invention, the hardness is 650 ΗV or more. The dimensional deformation (dimensional change rate) is the average 値 [(Δχ + Δγ + Δζ) when the thicknesses (Δ χ ), width (Ay), and length (Δζ) are measured before and after the aging treatment. /3], and the above-mentioned ΔΧ, Ay, Δζ maximum 値 (absolute 値) are evaluated. For the sake of convenience, the SU is called “the average 値 or average size deformation of the dimensional deformation rate”. The latter is referred to as "the maximum 値 or the maximum dimensional deformation rate of the dimensional deformation rate." In the second aspect of the present invention, the "average 尺寸 of the dimensional deformation rate" and the "dimensional deformation rate" are simultaneously used. The evaluation of the dimensional deformation after heat treatment in both of the maximum 値 is different from the conventional technique of measuring only the former (average 尺寸 of the dimensional deformation ratio) disclosed in Patent Document 2. According to the present inventors As a result of the experiment, it is known that if the dimensional deformation after the heat treatment is suppressed by the full -30-200831682, if the average 値 of the dimensional deformation ratio is made as small as possible as disclosed in Patent Document 2, It is not enough, but it is indispensable to make the dimensional deformation (degree of difference) in all directions of thickness, width and length become small. Sometimes it is: even if the average deformation of the dimensional deformation rate is suppressed, The case where the difference in the dimensional deformation ratio is still large (there is also the opposite case) (please refer to the embodiment described later). Further, in the second aspect of the present invention, the so-called "φ is very deformed after heat treatment. Small (having excellent dimensional deformation inhibition) means that when the dimensional change before and after the heat treatment is measured according to the method described in the column of the examples to be described later, the average 尺寸 of the dimensional deformation ratio is within ±0.03% and the size The maximum 値 (absolute 値) of the deformation rate is less than 0.05%. Further, the evaluation criteria (method and level) in the second aspect of the present invention are different from the first aspect of the present invention in the following points: First, regardless of the first aspect of the present invention Or, in the second aspect of the present invention, the "average 尺寸 of the dimensional deformation ratio" is used as the evaluation standard for the dimensional deformation after the heat treatment, but the first aspect of the present invention sets the qualification standard to ±0.05%. The second aspect of the present invention is stricter than the first aspect of the present invention, and the qualification standard is defined as 〇3%. Further, in the first aspect of the present invention, the "difference in the dimensional deformation ratio", that is, the difference 値 (absolute 値) between the maximum 値 and the minimum χ among the above Δχ, Ay, and Δζ is used. In the second aspect of the present invention, the "maximum defect of the dimensional deformation ratio" is adopted as described above. This is because -31 - 200831682 is based on the fact that the part (maximum enthalpy) that has the greatest degree of difference in heat treatment after heat treatment is required to provide the steel according to the first aspect of the present invention. In addition to the "difference in dimensional deformation rate" of the first aspect of the present invention described above, "large ruler" is used. As shown in the later-described embodiment, the "size change rate" specified in the first aspect of the present invention is satisfied, as shown in the following description. Example) "Steel having excellent heat treatment inhibition property" in the second aspect of the invention. The composition of the steel in the second aspect of the present invention is as follows in the predetermined range of various alloying elements which contribute to precipitation hardening, and is also controlled between the predetermined elements by the following formulas (1) to (4). The balance is used to seek sex. As shown in the later-described embodiment, if such a requirement cannot be met, the desired characteristics cannot be ensured. In the second aspect, the addition of three elements of Cu, Ni, and A1 may be lacking, for example, it has been confirmed from the experimental results that the steel of the composition of the patent document 3 does not contain Cu and Ni spear elements. In particular, the second aspect of the present invention is not obtained, and in order to reduce the dimensional deformation as much as possible, in addition to the mass ratio which constitutes the above & [Cu] and [C], it is appropriate to control The most indirect deformation rate described in the description of the more excellent dimensional deformation (the ability to become smaller) is that the maximum amount of the indifference steel which is invisible is not described as the subsequent dimensional deformation. In addition to the fact that the content is controlled at the site, and any of the above-mentioned specific elements are appropriately improved, the method of the present invention is not one of the above-mentioned patents [] A1. ) when Cr and C -32-

200831682 Product of the content ([] is the upper limit of [(:]), ci Si (upper limit), Μη (upper limit), Ms point (lower (upper limit), Ni amount (upper limit), Cr amount (upper limit) The method of X[W] (upper limit) is also very important. As the basics, the Ms point will become high and there will be little Vastfield inlays. In addition, the Cu and Ni alloys are properly controlled. The content of the component can therefore be significantly suppressed after the aging treatment of 4 00 to 5 50 ° C, after the surface hardening treatment. This is considered to be: by the addition of the above alloy composition, 400 to 500 ° C In the low temperature region, ε-Cu is mainly formed, and in the intermediate temperature range of °C, Ni-(Al,Mo) compounds are mainly formed, and in the high temperature region of about 50,000 to 550 °C, mainly Carbides are called, but the crystal structure of these precipitates (FCC || quality (BCC structure) is different, so the volume shrinks, and the deformation inhibition of f is helpful. Moreover, the present invention does not precipitate coarse Cr. Carbide, so which direction of crystallization is isotropic, so it is considered that even the shape of the mold In terms of manufacturing, it is also possible to effectively suppress the heat treatment and the second aspect of the present invention, in order to increase the softening amplitude of the HAZ of the weld bead, it is mainly to appropriately control the [Cr] limit, the Ms point (lower limit), and the C amount ( Lower limit), A1 amount | Quantity (lower limit), [Cu]/[Ni] (upper limit, lower limit) 〇.5x [W] (lower limit), 乂 quantity (upper limit), that is, (upper limit), spread), A1 The amount of [Mo ) +0.5 is based on the formation of a low C amount, and the formation of A1, in particular, about expansion and contraction, for example, in the case of about 450 to 530, intermetallicization of L into a Mo-V system. Base 〖after heat treatment' is designed to be as strong as possible. Manufactured in: large-scale complex: dimensional deformation ^ repairability (making X[C] upper: lower limit), Ni, [Mo]+ as used to make -33- 200831682 The design pointer of ΗAZ softening is not to use the hardening caused by the formation of granulated iron, but not only the amount of C is controlled to a low C amount of about 2 to 0.6 0 %, but also the utilization factor. Precipitation hardening due to the addition of alloy components (mainly A1, Cu, Ni, Mo, W) (for example: ε -Cu, Ni -Al-based intermetallic compound, Ni-Mo-based intermetallic compound). These precipitates are finely integrated and precipitated in the matrix, so the hardness is remarkably increased. φ, in particular, Cu, Ni, and A1 are important precipitation hardening elements and are important elements for suppressing HAZ softening. As a result of the experiment, it has been confirmed that the steel system which does not substantially add one of these elements cannot obtain the desired HAZ softening inhibition effect. Further, it is known that the ratio of [Cu] / [Ni] (the ratio of [Cu] to [Ni]) is in close contact with the suppression of HAZ softening, and by appropriately controlling the above ratio, HAZ softening can be suppressed. Hereinafter, the steel component in the second aspect of the present invention will be described. C: 0.20 to 0.60% C is used to ensure hardness and abrasion resistance, and is an element that helps to suppress the HAZ softening range. When a carbide film such as VC or TiC is formed on the surface of the mold base material by the CVD method, if the C concentration is too low, there is a problem that the thickness of the film is reduced. If these factors are taken into consideration and the above-mentioned effects are to be effectively exerted, the lower limit of the amount of C is selected to be 0.20%. The amount of C is preferably 0.22% or more. However, if the addition is excessive, the residual Worthite iron will increase. If the high-temperature aging is not performed, the expected hardness will not be obtained, and the expansion will occur after the aging treatment, and the dimensional deformation will become large. Therefore, the upper limit is selected to be 0.60%. The amount of C is preferably 0.50% or less, more preferably 0.45% or less. S i : 0 · 5 〜 2 · 0 0 %

Si is a deoxidizing element which can be used as a steel material, and is an element which contributes to the improvement of hardness and the machinability. Further, Si is also useful for suppressing the temper softening of the matrix of the granulated iron and suppressing the softening of the HAZ. In order to effectively perform this effect, the lower limit of the amount of Si is selected to be 0.5%. However, if the addition is excessive, the segregation becomes large, and not only the dimensional deformation after heat treatment becomes large, but also the toughness is lowered, so the upper limit is selected to be 2.00%. The lower limit of the amount of Si is preferably 1%, more preferably 1.2%, and the upper limit of the amount of Si is preferably 1.85%. Μη : 0· 1 ～2% • Μη is a useful element for ensuring hardenability, but if it is added excessively, the Ms point will be significantly lowered, and the residual Worth iron will increase, so if high temperature aging treatment is not performed, , the expected hardness cannot be obtained. In consideration of these factors, the content of Μη is selected in the above range. The lower limit of the amount of Μη is preferably 〇15%, and the upper limit of the amount of Μη is preferably 1%, more preferably 0.5%, and particularly preferably 0.35%.

Cr: 3.00 ~ 9.00%

Cr is a useful element for ensuring a predetermined hardness. If the amount of Cr -35- 200831682 is less than 3.0%, the hardenability will be insufficient and local iron will be formed, so the hardness will be lowered and the wear resistance cannot be ensured. 3. More than 5% is better, and 4.0% is better. However, excessive addition of a large amount of coarse Cr-based carbide is formed, and the durability of the film is obtained after the heat treatment, so the upper limit is selected to be 9.00%. 7.0% or less is more preferable, 6.5% or less is more preferable, and 6.0% or less is more preferably A1: 0.3 to 2.0%. A1 is an element necessary for improving the hardness due to precipitation strengthening of an Al-Ni-based material such as Ni3Al. The HAZ softening range is also helpful. Also, A1 can be considered as taking these factors into consideration, and the lower limit of A1 is selected as 〇 · 3 %. In the case of the amount, the segregation becomes large, and not only the difference in dimensional deformation rate after heat treatment, but also the upper limit of the toughness is selected to be 2.0%. The amount of A1 is preferably 0.50% or more, more preferably 0.7% or more and 1.6% or less. C u · 1.00 ~ 5%

Cu is an element which is required to be guided by the precipitation strengthening of ε-Cu. When the amount of the softening of the HAZ is excessively increased, the forged crack is likely to occur. The amount of Cu is preferably 2.0% or more and 4.0% or less. N i : 1 · 0 0 ～5 % The amount of toughened Cr is formed, and it will shrink, and the amount of Cr will be reduced by intermetallic, and the deoxidizer will be suppressed. However, the addition is over (especially reduced, so less than 1.8% of the hard lifting help. However, the upper limit is selected -36- 200831682

Ni is an element necessary for improving the hardness due to precipitation strengthening of an Al-Ni-based intermetallic compound such as Ni3Al, and is also useful for suppressing the softening range of ΗAZ. Further, the Ni system can be used together with Cu, whereby the bridging property at the time of forging can be prevented by suppressing the hot brittleness due to the excessive addition of Cu. However, if the addition is excessive, the residual Worthite iron will increase. If the high-temperature aging treatment is not performed, not only the predetermined hardness but also the expansion after heat treatment will be ensured. The Ni amount is preferably 1.5% or more and 4.0% or less.

Mo : 0.5 to 3% and/or W: 2% or less (including 0%)

Both Mo and W can form a Ni3Mo-based intermetallic compound in addition to the M6C-type carbide, and are useful for precipitation strengthening. However, when Mo and W are excessively added, the above-mentioned carbides and the like are excessively formed, which not only causes a decrease in toughness, but also causes dimensional deformation (especially, the difference in dimensional deformation ratio) after heat treatment to be large. range. In the present invention, although Mo is used as an essential component and W is used as a selection element, both may be used. The Mo system is preferably 0.5% or more and 3% or less, more preferably 0.7% or more and 2.5% or less. Further, W is preferably 2% or less, more preferably 1.5% or less. S : 0 · 1 0 % or less (excluding 0 %) S is a useful element for ensuring machinability. However, if excessive addition occurs, weld cracking occurs, so the upper limit is selected to be 0.10%. The amount of S is preferably 0.07% or less, more preferably 0.05% or less, more preferably 0.025% or less, and particularly preferably -37-200831682 In addition, the present invention must conform to the following formulas (1) to (4): {[] represents each element The meaning of the content (%)}. Formula (1) [Cr]X[C]S 3.00 The above formula (1) is set for the purpose of suppressing the formation of coarse Cr-based carbides, and the product of [Cr] and [C] exceeds 3.00. The dimensional deformation after heat treatment becomes large, and the durability of the surface film is lowered. The product of [Cr] and [C] is preferably 1.80 or less, more preferably 1.70 or less. In addition, the lower limit is based on the viewpoint of suppressing dimensional deformation after heat treatment, etc., and the smaller the better, but it is also considered to be effective in exerting the above-mentioned effects due to the addition of Cr and C. 0.8 is the appropriate formula (2) [Cu] / [Ni]: 0 · 5 ~ 2 · 2 The above formula (2) is mainly set to use the precipitation strengthening of ε - Cu to inhibit HAZ softening The parameters of the amplitude (please refer to the embodiment described later). In order to effectively perform this effect, the ratio 〔 of [C u] to [N i] is set to 〇 · 5. However, if the above ratio becomes larger, forging cracking occurs, so the upper limit is selected to be 2·2. The above ratio is preferably 7.7 or more and .5 or less is preferably 0.85 or more and 1.2 or less. Formula (3) [Mo]+ 〇.5x [W]: 0.5 to 3.0% The Mo and W systems constituting the above formula (3) are elements which are helpful for precipitation strengthening as described above, and the above formula ( 3) It is mainly set as a parameter for ensuring the hardness increase due to precipitation strengthening of these elements, and is also effective for suppressing the HAZ softening range. In the above formula (3), the coefficient (0.5) of [ -38 - 200831682 w] is determined in consideration of the atomic weight of Mo being about 1/2 of w. In order to effectively perform these functions, the lower limit of the above formula (4) is selected to be 〇. 5 %. However, if the amount of Mo and W is excessively added, the above-mentioned carbides will be excessively added, which not only causes a decrease in toughness, but also causes dimensional deformation (especially, the difference in dimensional deformation ratio) after heat treatment, so that the above formula The upper limit of (3) is selected to be 3.0%. The lower limit of the above formula (3) is preferably 1.0%, more preferably 1.2%, and the upper limit is preferably 2.8%. Formula (4) [Cu]/[C]: 4.0 to 15 The positioning of the above formula (4) is mainly used as a parameter for moving the peak of the hardness after heat treatment (after aging treatment) to the low temperature side. Thereby, dimensional deformation inhibition after heat treatment is sought. In general, the expansion dimensional deformation after the aging treatment (tempering) occurs due to the opening (decomposition) of the residual Worth iron during the melt treatment (quenching) (for example, please refer to FIG. 9 described later). As shown in the above formula (4), it is understood that Cu having an action of shifting the hardness peak after aging to the low temperature side and C having a close correlation with the residual Worthite iron are appropriately controlled. When the mass ratio (ratio of [Cu]/[C]), the dimensional deformation after heat treatment can be remarkably controlled. Fig. 1 is a graph showing the effect of the ratio 〔 of [Cu]/[C] when measuring the dimensional deformation ratio (average 値 and maximum 値) by the method described in the examples described later on the dimensional deformation ratio. This chart indicates the results of Νο.44 (steel type A), 52 (steel type C), 56 (steel type D), 70 (steel type J), and 7 2 (steel type) of Table 7 to be described later. These steel grades include -39- 200831682

There are approximately the same degree of C, Si, Μη, Cr, Al, Cu, Ni, Mo, W. As shown in Fig. 8, it can be seen that the specific enthalpy of [Cu]/[C] has a close relationship with the dimensional deformation ratio, and by controlling the above-mentioned specific enthalpy within the range of 4 · 0 to 15 The dimensional deformation ratio can be suppressed within the range defined by the second aspect of the present invention (the average 値 of the dimensional deformation ratio is ±0·03% or less, and the maximum 尺寸 of the dimensional deformation ratio is 0.05% or less). If the ratio of [Cu]/[C] is less than 4 · 0, the aging temperature at the peak hardness is much higher than the temperature at which the residual Worth iron begins to decompose. Therefore, the amount of expansion after aging treatment If the above ratio is more than 15 , the shrinkage with the increase in the aging temperature (which cancels out the expansion after the melt treatment) is no longer generated, and no matter which one, the predetermined one cannot be obtained. Resistance to dimensional deformation inhibition. The above ratio is preferably 5.0 or more and 1 or less, more preferably 6.0 or more and 1 or less. The components in the steel of the second aspect of the present invention are as described above, and the rest are iron and unavoidable impurities. Unavoidable impurities, for example, include elements that are inevitably mixed in during the manufacturing process, such as P, N, Ο, and the like. The amount of P is preferably 0.05% or less, more preferably 0.03% or less. The amount of N is preferably 350 ppm or less, more preferably 200 ppm or less, and particularly preferably 150 ppm or less. The amount of sputum is preferably less than 50 ppm, more preferably less than 30 ppm, and preferably less than 20 pm. The present invention is further based on the object of further improving other characteristics, and the following components may be added. V : 0 · 5 % or less (excluding 〇 % ) V is a carbide which can form Vc and is useful for lifting hardness -40- 200831682 , which is an effective element for suppressing the softening of HAZ. Further, when the surface of the base material is subjected to nitriding treatment such as gas nitriding, salt bath nitriding, or plasma nitriding to form a diffusion hardened layer, it is an effective element for improving the surface hardness and increasing the depth of the hardened layer. In order to effectively play this role, the amount of V is greater than that of 〇 〇 5% or more. However, if the amount of addition is too large, the amount of solid solution c will decrease, which will result in a decrease in the hardness of the parent phase, which is the structure of the granulated iron structure. Therefore, it is preferable to set the upper limit to 〇·5%. The amount of V is preferably 0.4% or less, more preferably 0.30% or less. At least one element selected from the group consisting of Ti, Zr, Hf, Ta, and Nb is 0.5% or less (excluding 0%). These elements are all nitride forming elements for the nitride and A1N. An element that contributes to the improvement of toughness caused by fine dispersion and grain refinement. In order to effectively exert such an effect, it is preferable that Ti is added in an amount of 0.01% or more, Zr is 0.02% or more, Hf is 0.04% or more, Ta is 0.04% or more, and Nb is 0.02% or more. However, if the amount of addition is excessive, the amount of solid solution C is lowered and the hardness of the granulated iron is lowered. Therefore, the total amount of the above elements is preferably 0.5%. The total amount of the above elements is preferably 0.4% or less, and more preferably 0.30% or less. Further, the above elements may be added singly or in combination of two or more.

Co : 10% or less (excluding 0%)

Co is used to increase the Ms point and reduce the effective elements of the residual Worthite iron, thereby increasing the hardness. In order to effectively exert the above effects, the Co amount is preferably 1% or more. However, if the addition is excessive, the cost and the like will increase, and it is preferable to select the upper limit as 10%. The upper limit of the amount of Co is -41 - 200831682 5.5% is better.麻田散铁转点点(M s点)g 1 70 °C Ms point = 550-361x[C]-3 9x[Mn]-35x[V]-2 0x[Cr] -17x[Ni] -10x [Cu] -5x( [Mo] + [W]) + 15x [ Co ) + 3 0x [ A1 ) {] is a meaning of the content (%) of each element} In the present invention, Ms The point is mainly used as an index for suppressing the dimensional deformation after hardness and heat treatment. If the Ms point is less than 170 ° C, the residual Worth iron will increase. If the high temperature aging treatment is not performed, the desired hardness cannot be obtained. It also causes expansion after heat treatment. The higher the Ms point, the better, about 23 ° C or better, 23 5 ° C or more, and 250 ° C or better. In addition, the upper limit is not particularly limited, but it is preferably about 350 °C in consideration of factors such as the effect of the addition of the above-mentioned elements constituting the Ms point, and the like. 320 ° C is better. Next, a method of producing a steel for a mold according to a second aspect of the present invention will be described. The production method of the present invention comprises the steps of: preparing a steel conforming to the above requirements, and performing the melt under the conditions of the following formula (5). Process the treatment of timeliness. ΤΑ-1 0 ^ T2 ^ TA + 1〇 (5) where ΤΑ - 0.29xT 1 -2.63x C Cu ] /[C]+ 225, -42- 200831682 τ 1 represents the melt temperature (° c), T2 is the representative aging temperature (°C). Specifically, after the steel conforming to the above requirements is first melted, hot forging is performed, followed by annealing (for example, after about 7 00 X: for 7 hours, at an average cooling rate of about 17 ° C / hr. After cooling in a furnace to about 400 ° C, cooling, softening, and then roughing into a predetermined shape by cutting or the like, and then performing melt processing and time-effects under the conditions of the above formula (5) Just handle it. As described above, in the second aspect of the present invention, the composition of the steel having a small amount of residual Worthite iron during the melt treatment is used, and Cu and C are further represented by the above formula (5). The mass ratio ([Cu ) / [ C ) ) is controlled by the relationship between the melt temperature Τ 1 and the aging temperature T2, and then it can be adjusted before the decomposition and expansion of the Worthite iron after the aging treatment. Since the hardness after aging reaches a peak, it is possible to simultaneously achieve both effects of dimensional deformation suppression and hardness after heat treatment. In general, in the production of steel for molds, the melt treatment is performed at a temperature of about 950 to 1150 ° C - aging treatment is performed at a temperature of about 400 to 530 ° C, According to the experimental results of the present inventors, it has been found that even if the melt treatment and the aging treatment are performed within the above range, the desired hardness is sometimes not obtained, and sometimes it is not sufficient. The dimensional deformation after heat treatment is suppressed (refer to the examples described later), and therefore, the above formula (5) is defined. When the above-described mechanism of the present invention is compared with the method of the above-mentioned Patent Document 2 (corresponding to the conventional high-C high-Cr steel), Patent Document 2 is the second drawing of the present invention as in -43-200831682 (corresponding to the patent document 2) As shown in Fig. 1 , in the case where the residual Worth iron has a certain degree of decomposition, the tempering process which makes the dimensional deformation at the time of tempering tend to zero is performed, and the present invention is relatively The tempering process is performed before the residual Worth Iron begins to decompose or just begins to decompose the subsequent temperature, and at this point, the two are different. That is, the present invention performs aging treatment at a lower temperature (specifically, a large enthalpy is a low temperature of about 50,000 ° C or less) as compared with the conventional high C high C r steel. According to the present invention, the aging treatment is not performed in the field where the dimensional deformation after heat treatment is intense (the A field in Fig. 3) as in Patent Document 2, but it is considered to be capable of generating a large amount of stable residual wavy. The aging treatment is performed in the field of the field iron (the field B in Fig. 3), and therefore, steel having a smaller degree of difference from the dimensional deformation of the steel disclosed in Patent Document 2 can be obtained. Further, by performing aging treatment in a relatively low temperature field in this manner, the stability of the residual Worthite iron can be improved, and the change over time of the remaining Worthite iron becomes small, so that dimensional deformation after heat treatment can also be obtained. The effect of the change over time becomes smaller. The aging temperature T2 is preferably TA ± 5 ° C as described above. Further, the melt temperature T1 can be used in the production of steel for a mold, which is lower than the range generally employed, so that the heat treatment can be less deformed. Specifically, it is preferable that the large enthalpy is in the range of 900 to 1150 ° C. The present invention is suitable in that the temperature of the melt treatment and the aging treatment is appropriately controlled in the above manner, and the time is not particularly limited. The limitation is as long as it is carried out under the conditions generally used in the manufacture of steel for molds. -44- 200831682, the smelting time (heating time) is controlled to the extent of 1 to 5 hours, and the aging time (holding time) ) Control can be done in 2 to 8 hours. [Examples] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to the following examples, and may be applied with appropriate modifications within the scope applicable to the above-mentioned gist. It is possible that these are also included in the technical scope of the present invention. First, the implementation of the first aspect of the present invention will be described. Using the various steel types No. described in Tables 1 and 2, 150 kg of steel embryos were melted in a vacuum induction melting furnace, heated to about 900 to 1 150 ° C, and forged into two sheets of 40 mm Tx 75 mm W x about 2000 mm L steel sheets, and then about The average cooling rate of 60 ° C / hr was slowly cooled. After cooling to a temperature of 100 ° C or less, it was again heated to a temperature of about 850 ° C, and slowly cooled (annealed) at an average cooling rate of about 50 ° C /hr. The following tests (1) to (4) were carried out using various annealed materials obtained by the above methods. (1) Hardness test (measurement of maximum hardness) A test piece having a size of about 20 mm Tx 20 mm Wx 1 5 mmL was cut out from the above-mentioned annealed material to obtain a test piece for hardness measurement, and the test piece was subjected to the following heat treatment. Melt treatment (quenching treatment): at about 1〇2〇~l 〇30°C -45- 200831682 1 20 minutes of heating in air cooling - aging treatment (tempering treatment): about 400~5 60 ° C keeps about 3 hours - let cool. As described above, the hardness at the time of changing the tempering temperature in the range of about 400 to 5 60 ° C was measured by a Hardness Durometer (AVK, manufactured by AK AS HI, load: 5 kg), and the maximum hardness was found. (HV). In the present embodiment, those having a maximum hardness of 650 HV or more are regarded as pass ((). (2) Dimensional deformation test (measuring the difference between the average 値 and the dimensional deformation rate of the dimensional deformation ratio) A test piece having a size of about 40 mm Tx 70 mmW x 1 OO mmL was cut out from the above-mentioned annealed material to obtain a test piece for measuring the dimensional deformation. This test piece was subjected to the same melt treatment as the hardness test of the above (1), and then tempered at a temperature at which the maximum hardness was reached. Then, the "average 尺寸 of the dimensional deformation rate" and the "difference of the dimensional deformation rate" are measured in the following manner, and both of the evaluations are qualified according to the following criteria, and it is considered to have excellent heat treatment. Dimensional deformation inhibition (qualified). (2 -1 ) Measurement of the average dimensional deformation rate 値 The test piece for the dimensional deformation measurement (before the post-annealing melt treatment) and the tempered test piece were measured for three directions of thickness, width, and length, respectively. The difference 厚度 of the thickness before and after the heat treatment, the difference in width, and the difference in length were determined, and the average enthalpy (percentage) of these was taken as the "average 尺寸 of the dimensional deformation ratio". In the present embodiment, those who are "average 値 of the dimensional deformation rate" ± 0 · 0 5 % are regarded as qualified (〇), and those exceeding ± 0.0 5 % are regarded as not -46-200831682 qualified (X). (2-2) Measurement of the difference in dimensional deformation ratio The test piece for the dimensional deformation measurement (before the post-annealing melt treatment) and the test piece after the tempering were measured for three directions of thickness, width, and length, respectively. The difference 厚度 of the thickness before and after the heat treatment, the difference 宽度 of the width, and the difference in length were determined. The difference (percentage) between the maximum 値 and the minimum 这些 among these rates is taken as the "difference in the dimensional deformation rate". When the difference φ of the dimensional deformation ratio is 0.08% or less, it is regarded as pass (〇), and when it exceeds 0.08%, it is regarded as unacceptable (X). (3) Welding test (measurement limit preheating temperature and HAZ softening range) A test piece having a size of about 40 mmT x 45 mmW x 7.5 mm was cut out from the annealed material described above as a test piece for welding. The test piece was subjected to a melt treatment and a tempering treatment in the same manner as the dimensional deformation test of the above (2). Φ Next, the tempering material obtained in this manner is processed to obtain a sheet as shown in Fig. 3(a). The sheet material of Fig. 3(a) has a groove portion as shown in Fig. 3(b). Next, a TIG electrode (the other part: 鉄 and unavoidable impurities; unit: mass %) having the composition shown in Table 3 ("TIG" manufactured by Yokohama Co., Ltd., Japan) was used. -Tectic 5HSS", φ 2.4 mm), thickening welding was performed on the groove portion of the above-mentioned sheet material in accordance with the following conditions. Welding conditions: Current: 150A, voltage: 11V, welding speed: 9.5~14cm/mm -47- 200831682 Temperature between each welding: Preheating temperature below heat: 7.1 ~1 〇.4kJ/cm Preheating: no pre- Heat, preheating (1 〇〇 °C, 2 0 〇, 300 °, 300 ° C) In addition, for No. 22 and No. 23 of Table 2 (both are analog traditional high C high In order to prevent the influence on the base material composition during welding, the welding material is thickened on the opening surface (pre-stack welding) as shown in Fig. 4 . In the pre-stacking welding, the TIG welding rod ("GSS-5 0", Φ 2.4 mm) manufactured by Kobelco Co., Ltd. was used for the pre-stack welding. The welding conditions are the same as described above. Composition of TIG welding rod for pre-stack welding: 〇.〇9%C-0.93 % Si -1.9 5%Mn-0.00 9%P-0.0 1%S (the rest: 鉄 and inevitable impurities; unit: Mass %) When the preheating conditions were changed as described above, the lowest temperature (limit preheating temperature) at which the crack did not occur in both the weld metal (DEPO) and the HAZ portion was measured. The lower the preheating temperature of the boundary, the less likely it is to crack. In the present embodiment, it is considered that the limit preheating temperature is 200 °C or less, and it is considered to be good (X). In addition, in order to investigate the hardness distribution of the cross section of the test piece after thickening and welding by the above-described limit preheating temperature, from the position of the weld fusion line (fusion line) of the 1/4 portion of the sheet thickness to the position of leaving the 30 mm. The hardness was continuously measured at a pitch of 1 mm each time. The distance from the center of the weld metal to the position where the hardness is reduced to 600 HV or less is regarded as "HAZ soft -48- 200831682". For the purpose of reference, the field of measurement of the softening amplitude of ΗAZ is shown in the first drawing. In this embodiment, the softening width is 6.5 mm or less, which is superior to the welding repair 〇), and the 6.5 mm is evaluated as the poor weld repairing property (X) 〇 (4) Toughness test for the above annealing The following heat treatment was carried out on the material. Melt treatment (quenching treatment): heating at about 1 0 2 0~1 〇3 0 °C for 120 minutes -> cooling in air - aging treatment (tempering treatment) about 400~5 60 °C for about 3 hours ―Cooling or cooling in the air. Then, as shown in Fig. 5, a test piece having a notch portion of l〇mmR was cut out as a test piece for measuring toughness (Xia's test piece). This test piece was used to carry out the Chardonnay test and to determine the absorbed energy at room temperature (Xia's). The Xia's test film system took 3 pieces each, and the average of these 3 pieces was taken as Xia's. In the present embodiment, it is "excellent in toughness" in which Xia's is washed into 15J or more. These results are not shown in Tables 4 to 5. Display HAZ sex (for: V-type test and test rushing rushing evaluation -49- 200831682

i σ> eo CM 3 C3 Csl S 〇> CM 00 s CO CO σ> CM o 〇> CM 卜 CO CSI if co CO § C^J 00 eg <0 CO CSJ <〇eo CM <P 00 CM €M <〇u> CM CM ΙΟ <〇σ» ο + CM 11 so CO ss C4 OJ § o CSJ· so Csl tn Oj C4 esi <〇CSJ e^4 CSI Cl $ 12 P pp CNJ q 卜 in Bu CO eo Q o eo CJ in g 3 pps O p ο ο ts in oa g 5 s 〇>a> in CM s 8 〇> o IO CM \n CM m C4 s CO Pan GO to &lt 〇co _ 缄 S mi mi 赵 赵 赵 m m 赵 赵 o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o ο ο P ooooooooooooooooo ο ο > so 8 o CSI o CM· o CM· o 0 01 04 sosooo CM· o CSJ oo e>| -»* oos C^I CS| so ? ο S ο CO inch 1 sospgqgpgogosogpgpgps ogpsogospsogpgp S ο ο S ο CL CO o Oi qa% p 0 0 osp 〇> 〇· eo p 〇» p 〇> p CO 〇· Oi p 〇> p 〇> •^· p 00 p 〇> oi 〇> p oo o σ> 〇· 卜ρ σ> ο ο 〇C7 osop C7 〇o CO ooooooooopoop inch sooosooo to oooopop in oo CO op CO -op <〇ooc*> 〇o «ο ο 〇· ο ρ z « 〇· to p TP· oo CM po σ> CM p CO oooosoi; ▼«· oop « 5 oo • oo oo C9 op in CO ▼» o 9 -O oo ? p oo C9 p ο CO ο ο σ> CM ρ 5 C«lp CM p CM 〇o T— o § C4 oso in in og CSJ o ev o CM ps C^los CM os § CM 〇· ο ο ο ρ ^os -T-· g c4 ss CM €>l CM 04 Τ» o * 8 ss ▼— s 8 $ CM CSI CO «VI Csl z in 〇> c4 〇> cvi eo o 04' to 〇> CM· o CO 〇>〇> c4 σ>〇> CSI o CO Oi a&gt 04 s CM* 〇>σ> 〇4 r- Oi 04 IO 0> ¢4 s> 〇4 CO σ> C4 〇 〇> eo 〇> csi 60 a% oi 60 Oi 〇j 〇> 〇 > οά βο Oi oi δ p CO o CO g <*> o CO s CO l〇in CM ss csi CO I O ^r- o <〇ir> in » S CO CM so σ> o <〇o CO ossp CO ο CO Ρ co < P sssosssssoosos A sss T— ό in 〇> CO 〇> to 〇&gt ;s <D 〇% 卜α>〇> eo Oi σ>〇>〇> s (d 00 o\ σ> 〇i CO a> δ — in 5 o 5 o 5 Oi 〇> «ο JO 5 c 〇〇CSJ l〇CM o ιο CSI CO CM 〇CO CSI Ο) CSI Oi C4 Oi CM o oo CM O oo CSJ Oi 04 oo <〇CM o eo to CSJ CM O' IO CSI <〇CVJ In Cv) in ο u> CM CM CM .<〇in t>> ▼— o oo Τ» CM CO ▼—cn CO -r— in o in CO CO CO CM CO CO CO tn CO <〇 C9 s CO CO CO CO 〇> CO in <〇in co 00 CO CO CO l〇<〇Ο in C^l tf> CSI 〇evi <〇CM 〇IO CM 〇CM·inch CSJ o IO CM o 卜 C4 〇 CM·; S o to C4 IO CiJ o in CM o u> CSI ii> CM oo eg gas 〇 · osd - CSI CO to < 〇 CO CO a> 〇CnI CO to <〇CO σ> 8 -50- 200831682

(0 Έ <〇CVJ 1 -16 1 309 157 286 | in a> cm CO o ”20 CO eg 308 CM CM C7 342 ] ?si CO CM u> CO IO Csl CO S CM co QO esi 1—· oo C4 CM 288 | [Μ〇> [W]/2 «Μ °1 $ a CO CV{ CM s co Ol a CSJ 04 5 $ eg CM· SS 0.30 3.15 $ 1.2t 1 0.63 α> ο g 1.02 o (4) o O lo.so 0.33 0.02 60.20 .〇2.30 〇S 〇ogg [Cr> [C] 18.03 8.46 0.94 3.02 Si· Strict s 1.23 s 1.24 1.19 co 〇{ 1.19 o <N 00 0.75 2.25 1.28 s Sj | Unit: mass%) 2 ο ο ο ο O ooooooooo' o O oooo 〇o ο ο ο ο oo oooooooooooooooooo master ο ο ο oooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo ; 0.25 0.09 0.20 0.20 04 0.20 ca 0.20 0.22 0.20 0.20 0.20 0.20 0.20 0,20 0-20 0.22 0.20 0.20 I0.60 0.20 CO 0.005 0.007 0.004 0.004 0.004 0.004 0110 0.004 0.004 0.005 0.004 0.004 0.004 Γο,οοί 0.0041 0. 004 0.004 0.004 0.003 0.004] 0.005 0.004 ο. 0.018 0.019 0.018 0.020 0.019 0.019 ^.019 0.019 0.018 0.018 0.018 0.019 0.018 0.018 0.018 0.018 0.020 0.019 0.019 ^019 [0.019] Account S PER ο 10.00151 0.0007 10.0013] 0.0013 0.0015 0.0013 10.0014 10.0015 0.0013 0.0013 f 0,0015] 10.0013 10.00141 |a〇D14| 10.0013 0.0015 0.0013 0.0014 0.0015 10.0013] 0.0014 0.0013 Pro K- ζ 0.0130 0.0068 0.0140 0.0131 ΓΟ0135 0.0142 0.0140 0.0141 0.0135 |aoi33| 0.0140 0.0131 10,0129 0.0135 0.0141 |a〇135| 0.0135 0.0132 0.0140 | 0.01411 0.01381 0.0133 S 0.35 0.39 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0,02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.20 2.00 0.02 0.02 酦Φ • Plated ο g 0.91 8 8 iq ao S! 5 S 5 8 8 Esi 0.20 2.15 SS t ζ D.08 0.44 2.97 2.95 M 2.98 οί 2.98 2.98 net 6.10 2.98 m 0,05 2.97 CM c> 2.99 2.97 2.98 2.99 (4) 2.96 δ 0.05 0.40 ο CO 1 3.02 s 3.03 3.01 3.02 oo 3.02 0.98 0.05 3 CO 3.01 3.03 3.01 3.02 1 3.03 3.02 3.01 0.05 0.33 , 1.02 opg 0.48 2.05 p 1.02 1.02 wg 0.05 w 1.01 p 1.02 p 'T- wg ό 12.10 8.38 "4.93 (4) 4.96 4.94 4.90 4.97 4.96 4.96 4.93 4.98 4.93 2.99 o a> 4.94 4.95 4.95 0.42 0·60 0.28 0.28 0.28 2.10 0.28| 0.28 0.29 0.29 0.28 0.26 0.27 0.27 0.27 0.26 0.28 0.28 0.28 0.27 L^5j 0.28 0.26 <〇0.35 1.06 C>l <〇(4) "2.02 IX> CO to CO 1.33 1.33 €M C> 1.32 1.32 €*>· 1.39 1» c> CNi co s M CM 〇ο $ ο <C> 0.25 0.25 0.24 0.25 0.25 0.25 0.24 0.25 0.24 0.24 H 0.25 0.25 0.25 0.26 M 0.25 0.25 i C0 CM ir> CM 5 SS Jo S 8 SS 〇5 o -51 - 200831682 [Table 3] The rest: Iron and inevitable impurities (unit: mass%) C Si Μη V Ni Cr Mo Cu Al PSV 0.25 0.40 1.40 0.2 3.0 5.0 2.3 3.0 1.0 0.02 0.005 0.2 [Table 4]

No. Maximum hardness HAZ Softening range limit Preheating temperature Dimensional deformation rate Average 値 Size Deformation rate difference 値 丕 値 値 HV mm °C % % J 1 685 5.1 100 0.01 0.04 22 2 702 5.3 100 -0Ό1 0.05 20 3 710 4.8 25 0 0.06 19 4 715 4.5 100 0.02 0.05 17 5 713 4.6 100 -0.02 0.04 18 6 655 6Λ too 0.02 0.07 27 7 663 5.9 too 0.01 0.05 24 8 679 5.6 100 0 0.05 22 9 712 6.2 too 0.02 0.06 17 10 682 5.6 100 0 0.04 20 11 660 6.4 100 0.01 0.04 25 12 688 5.0 100 -0.05 0.08 22 13 683 5.1 100 0.01 0.04 35 14 683 5.0 100 0.01 0.04 33 15 685 5.1 too 0.01 0.04 33 16 680 5.0 too 0.01 0.04 32 17 710 5.2 200 0.03 0.05 17 18 720 5.3 200 0.03 0.04 16 19 685 5.1 200 Q.D3 0.05 22 20 680 5.3 200 0.04 0.05 21 21 722 4.9 200 0 0.03 25 -52· 200831682 [Table 5]

Να. Maximum hardness HAZ^ Width limit Preheating temperature Dimensional deformation rate 卒 値 値 变形 变形 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値 値13 24 645 7.0 25 -0.02 0.04 35 25 715 5.2 300 0.06 0.10 14 26 725 4.5 too 0.05 0.09 12 27 722 5.1 100 0.06 0.08 15 28 688 5.3 300 0.01 0Ό4 19 29 638 8.4 100 0.04 0Ό5 33 30 700 4.6 too -0.02 0.09 19 31 640 7.5 100 0.03 0.04 20 32 646 6.3 100 0.06 0.08 40 33 645 6.6 100 0.05 0.04 37 34 620 7.5 100 0.06 003 30 35 625 7.3 100 0.06 0.04 29 36 630 7.0 100 0.06 0.03 33 37 661 7.0 too 0.01 0.03 19 38 647 6.5 100 0Ό2 0.05 39 39 683 4.9 100 -0.06 0Ό9 21 40 629 6.9 100 0.05 0.05 35 41 723 5.0 100 0.03 0.10 13 42 640 7.0 too 0.02 0.05 35 43 630 7.7 100 0.02 0.04 33 From Table 4 and Table 5 The following findings can be obtained. Nos. 1 to 21 of Table 4 are examples of N 0.1 to 2 1 using Table 1 in accordance with all the requirements of the present invention. "All of them are not only high in hardness", and have excellent dimensional deformation inhibition after heat treatment and welding. In addition to the repairability, the toughness is also high, and the preheating temperature of the boundary is also a good grade below 200 °C. On the other hand, N 〇 · 2 2 to 4 3 of Table 5 are examples of N 〇. 2 2 to 4 3 of Table 2 which are not one of the requirements of the requirements defined by the present invention, and have the following defects. . -53- 200831682 No. 22 and 23 of Table 5 are examples of No. 22 and 23 of Table 2 which simulates a conventional high-C high-Cr steel because the product of [Cr] and [C] is large, Ms The point is very low, and the difference between the HAZ softening range and the dimensional deformation rate is increased. Further, since these steel grades have a lower tempering temperature, the hardness becomes higher. Therefore, the tempering temperature when the above steel grade is used is selected to be 5 1 〇 ° C, and various characteristics are measured. In No. 24 of Table 5, the example of No. 24 of Table 2 having a small amount of C was used, and the decrease in hardness and the increase in the degree of softening of HAZ were observed. In No. 25 of Table 5, the amount of C is large, and the product of [C〇 and [C] is large, and the Ms point is very low. The example of Νο·25 of Table 2 has poor dimensional deformation inhibition after heat treatment. In No. 26 of Table 5, the No. 26 of Table 2 having a large amount of Si was used, and although the average 尺寸 of the dimensional deformation ratio after the heat treatment was good, the difference in the dimensional deformation ratio was large. In No. 27 of Table 5, the example of No. 27 of Table 2 in which the amount of Μη is large and the Ms point is very low is used, and the average 値 of the dimensional deformation ratio after heat treatment is large. No. 28 in Table 5 is an example of No. 28 in Table 2 in which the amount of S is large. The limit preheating temperature is high, and there is a concern that weld cracking may occur. In No. 29 of Table 5, the No. 29 of Table 2 in which the amount of Al was small was used, and the decrease in hardness and the increase in the HAZ softening range were observed. In the case of No. 30 of Table 2 in which the amount of A1 is large, the average enthalpy of dimensional deformation ratio after heat treatment is good, but the difference in dimensional deformation ratio is large. In Table 5, Νο·3 1 uses a small amount of Ni, and [Cu]/[Ni] _ 54 - 200831682 is an example of Νο·31 of Table 2 which is very large, and it can be seen that the hardness is softened. increase. In the example No. 32 of Table 5, the example of Table 2 having a large amount of Ni was used, and the hardness was lowered and the dimensional deformation ratio after the heat treatment was increased. In the case of Νο·33 in Table 5, the amount of Cu was small, and the case of No. 3 of Table 2 in which [Cu] / 値 was small was small, and the increase in the softening degree of hardness was observed. In the No. 34 series of Table 5, the amount of Cu was not substantially added, and No. 34 of Table 2, which has an extremely small amount of Cu of 0.05% and a small amount of [Cu] / is used, is used. Drop > Increase in softening. In addition, the dimensional deformation rate after heat treatment is also increased. No. 35 in Table 5 simulates the case where Ni is not substantially added, and the amount of Ni is only 〇·05% is extremely small, and the ratio of Cu: is smaller than that of No. 3 of Table 2, so It can be seen that in addition to the increase in hardness and HAZ softening amplitude, the average size of the heat treatment after heat treatment is also increased. No. 36 in Table 5 simulates the case where A1 is not substantially added, and the amount of A1 is only 〇·〇5% which is extremely small in Table 2, so that the hardness reduction and the HAZ softening range can be seen, heat treatment The average 値 of the dimensional deformation rate also increases. In Table 5, No. 3, the amount of Cu and the amount of Ni are in accordance with the present invention, but the ratio of [C u]/[N i] is small, and the uniformity of HAZ Νο·32 is also increased. '[Ni] is lower than the case of HAZ steel [N i] and the average amount of HAZ is steel] / [Ni] degree of reduction of deformation rate of steel f N 〇. 3 6, increase In the case of N 〇· 3 7 -55- 200831682, the HAZ softening range has increased. In the case of No. 38 of Table 2 in which the amount of Cr is small, the hardness is lowered. In the example of Table 2: (1: a large amount of Table 2: ^〇.39, the dimensional deformation inhibition after heat treatment is not good. The Νο·40 series of Table 5 is used [ The total amount of Mo]+ 〇.5x[ W] is very small. In the case of Νο·40 of Table 2, it can be seen that the hardness is reduced and the HAZ softening amplitude is increased. Table 5 of Ν 〇 · 4 1 is used [ Μ 〇]+ 〇· 5 X [W] The total number of the No. 41 in Table 2 is good, although the average 尺寸 of the dimensional deformation ratio after heat treatment is good, but the difference in dimensional deformation ratio is large. The No. 42 system used the example of No. 42 of Table 2 in which the amount of Ti was large, and the decrease in hardness and the increase in the degree of softening of the HAZ were observed. For the sake of reference, the method according to the foregoing method will be obtained in FIG. The curve of the hardness distribution is indicated. In the figure, the steel () of the present invention represents the result of Ν 〇 4 of Table 1, and the conventional steel (♦) of S KD 1 1 represents the result of No. 22 of Table 2. As can be seen from the results shown in Fig. 7, when the steel of the present invention is used, the HAZ softening after welding can be more significantly suppressed than that of the conventional steel. The second aspect of the invention is as follows. Using the steel grades A to K described in Table 6, 150 kg of steel embryos are melted in a vacuum induction melting furnace, and then heated to about 900 to 1150 ° C, forging two pieces of 40 mm Tx 75 mm Wx. A steel plate of about 2000 mmL is then slowly cooled at an average cooling rate of about 60 hr / hr. After cooling to 100 ° C at a temperature of -56-200831682, it is heated again to a temperature of about 850 °C. The average cooling rate is gradually cooled (the test using each of the retreats 4 to 2) obtained in the above manner is performed. (1) Hardness test (measurement hardness) The size of the annealed material is approximately The test piece of 1 5 mm L was used as the test for hardness measurement φ. The melt treatment was carried out under the conditions described in Table 2. After the treatment, it was allowed to cool. The time for the treatment of the melt treatment was about 3 times. The hardness after the aging treatment was measured by AKAS HI, and the hardness was 650 HV or more in the examples. (2) The dimensional deformation test (the maximum 値 of the dimensional change rate) Annealed material cut out size For the test piece of 100 mmL, it was measured as a dimensional deformation. After the melt treatment was carried out under the conditions described in Table 2, it was allowed to cool. Next, the average deformation rate of the following deformation rate and the "size deformation rate" In the most standard, the evaluation of the dimensional deformation of these items is acceptable. (2 -1 ) The average 値 degree of the dimensional deformation rate is measured and annealed at about 50 ° C / hr.) The following (1 20mmT x 20mmW , piece, this test piece, air cooling - aging for about 120 minutes, aging specification AVK, load hardness (HV). In this • is qualified (〇). The average 値 and the rule of the shape rate 〖40mmT χ 70mm W χ test piece, then, • fan cooling aging method to determine the "size 値", according to the following, considered as heat treatment (average size deformation rate -57- 200831682 The test piece for measuring the dimensional deformation (pre-annealed before melting) was measured for thickness, width, and length in three test directions, and the difference in thickness and width between before and after heat treatment were determined. For the difference in length, the average 値 (percentage) of these rates is taken as the average 値 of the deformation rate. In this embodiment, the average 値 of the dimensional change is ±0 · 〇3 % or less. Qualified (〇), the one exceeding ± 0 is regarded as unacceptable (X). Φ ( 2-2 ) The maximum 値 of the dimensional deformation rate (maximum dimensional change) The test piece for the above dimensional deformation measurement (melted after annealing) Before and after the test, the thickness, width, and length of the test piece were measured, and the difference 厚度, the difference in width, and the difference in length of the thickness before and after the heat treatment were determined, and the absolute enthalpy of the maximum enthalpy (%) ) "ruler The maximum deformation rate is 値". The maximum value of the deformation rate of 0.05% or less is regarded as qualified (〇), and the case where more than 0.05% is regarded as #格(X). (2-3) The difference of the dimensional deformation rate is measured _ In order to provide a reference, the "dimensional deformation rate difference" described in the first aspect of the present invention is also measured. Specifically, the above-described dimensional deformation measurement test piece (melting after annealing) In the test piece after the time-effect, the thickness, the width, and the length of the three directions were measured, and the difference in thickness, the difference in width, and the difference in thickness before and after the heat treatment were determined. The difference between the maximum 値 and the minimum 这些 among these (Percentage is regarded as "the difference in dimensional deformation rate". The difference between the dimensional deformation rate and the "shape rate.03% of the shape rate" is regarded as the ambiguity. ) Square length rate) - at -58· 200831682

Those below 0.08% are considered qualified (〇), and those exceeding 0.08% are considered as unqualified (X). These results are shown in Table 7. -59- 200831682

12.041 12,001 14.001 7.50 I 4,44 I 0.03 I 0.40 I 3.92 I 16.001 0> 296 CO CM 303 278 ΙΟ CM τ— ΙΟ €Μ -261 -16 308 278 [Mo]+ m/2 1.80 1.22 1.80 1.22 0.90 OJ CM · τ— ΙΔ^ a 1.02 Ρ 0.52 0.83 Ρ 2.00 0.63 0.91 0.33 [Cr]* [C] SS 〇> ιηχ S CO 2.00 18.03 8.46 « CVI 1,23 m:Mi%) ο ο ο Ο .〇to ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο : iron and inevitable miscellaneous CL 0.018 0.020 0.019 0.019 0.020 0.019 0.019 0.018 0.019 0.019 0.019 Ο 0.0013 0.00141 0.0013 0.0013 0.0014 0.0013 0.0013 0.0015 0.0007 0.00131 0.0013 ζ 0.0148 0.01411 0.0129 0.0140 I 0.0141 0.0140 0-0140 O.Q13〇| 0, 00681 0.0131 0.0131 0.02 ο 0.02 0.02 ο 0.02 ο 0.35 0.39 0.02 0.02 SS 5 SS 5 1· ο 0:91 5 2 Μ 2.98 2.99 Μ 3.00 \2Μ\ 1.00 0.08 0.44 2.98 2.98 d 1 3.00 (4) Μ 3.50 3.00 2-00 0.05 0.40 0.98 4.00 < 1.09 ρ 1.02 Μ 〇τ — S 0.35 0.05 0.33 Μ 1.02 ό 4,95 4.96 4.97 4.99 to 0> 4,45 4.45 12.10 8.38 4.93 4.93 0.28 0.28 0.29 0.29 0.28 L^sj 0.42 0.60 0.26 0.26 ω 1.32 1-39 Μ CO 1.39 Μ ιη CO 0.35 1.06 Μ 1.33 ο 0.25 0.25 0.24 0.25 0.25 0.40 0.45 1.49 1.01 Μ 0.25 steel type < CQ ο ο Ιϋ U. ο X

-60- 200831682 [Table 7]

No. Steel seed melting temperature TK°C) Aging temperature T2 (〇C) Hardness (HV) Size deformation rate (%) ΤΑ* Scope of the invention (TA±10) 値 値 値 値 値 A A 44 A 1020 489 479-499 490 675 0.010 0.030 0.040 45 950 469 459-479 470 678 0.000 0.020 0.040 46 1020 489 479-499 520 640 0.035 0.060 0.050 47 1020 489 479-499 460 642 0.035 0.060 0.050 48 B 1020 489 479-499 490 685 0.010 0.030 0.040 49 950 469 459-479 470 683 0.000 0.020 0.040 50 1020 489 479-499 520 652 0.040 0.065 D.050 51 1020 489 479-499 460 649 0.035 0.060 0.050 52 C 1020 504 494-514 500 655 0.020 0.050 0.060 950 484 474-494 485 484 475 675 -0.010 0.035 0.050 58 1020 495 485-505 530 670 0.030 0.055 0.050 59 E 1020 484 474-494 485 713 -0.020 0.040 0.040 60 950 464 454-474 465 710 - 0.030 0.050 0.035 61 950 464 454-474 480 680 -0.050 0.070 0:035 62 F 1020 501 491-511 500 710 0.030 0.050 0.040 63 950 48t 471-491 480 720 ooto 0.030 Q.035 64 1020 501 491-511 520 675 0.050 0.070 0.040 65 G 1020 509 499-519 510 700 0.030 0.050 0.040 66 950 489 479-499 490 695 0.020 0.040 0.040 67 1020 509 499-519 530 690 0.060 0.080 0.040 68 H 1020 521 511-531 520 690 0.060 0.135 0.150 69 I 1020 520 510-530 520 720 0.010 0.070 0.120 70 J 1020 510 500-520 510 645 0·03 ❹ 0.060 0.060 71 950 490 480-500 490 640 0.025 0.055 0.060 72 K 1020 479 469-489 480 720 0.025 0.055 0.060 73 950 458 448-468 460 715 0.020 0.065 0.060 ※丁八* =0.29 x T Bu 2·63 X [Cu]/[C]+225 -61 - 200831682 The following findings can be obtained from Table 7. First, No. 44 to 47 of Table 7 were investigated for the characteristics of the steel type A in Table 6 in which the steel component was in accordance with the requirements of the present invention, and the melting temperature T1 and the aging temperature T2 were variously changed. Among them, No. 44 and No. 45 are aging temperature T2 in accordance with the range of the present invention (TA ± 10 (:)), both of which have high hardness and excellent dimensional deformation inhibition after heat treatment ( Not only the difference in the dimensional deformation ratio, but also the average dimensional deformation ratio and the maximum dimensional deformation ratio are excellent.) In contrast, No. 46 is a comparative example in which the aging temperature T2 is outside the range of the present invention, and No. 47 is the aging temperature T2. In the comparative examples which are less than the range of the present invention, both of them have low hardness, and the difference in dimensional deformation ratio after heat treatment is good, but the average dimensional deformation ratio and the maximum dimensional deformation ratio are lowered. No. 48 to 51 are inspected for the steel type B in Table 6 which is a component of the steel in accordance with the requirements of the present invention, and the melting temperature τ 1 and the effective temperature # degree T2 are variously changed. 4 8 and No. 49 are examples of the invention in which the aging temperature T2 is in the range of the present invention (TA; t10 ° C), both of which have high hardness and excellent dimensional deformation inhibition after heat treatment. , No. 50 is the aging temperature T2 is beyond this In the comparative example of the range of the brightening, No. 51 is a comparative example in which the aging temperature T2 is lower than the range of the present invention, and both of them are the difference in the dimensional deformation ratio after the heat treatment, although the average dimensional deformation ratio and the maximum dimensional deformation are good. In addition, No. 51 has a lower hardness. -62- 200831682 Further, No. 52 to 55 of Table 7 are the steel type C of Table 6 which uses the requirements of the steel invention, and the melting temperature is set. The degree T2 was investigated for various characteristics. Among them, No. 52 and No. 53 are examples of the present invention in the range of the aging temperature T2 (TA ± 10 ° C), both of which are hard and excellent dimensional deformation after heat treatment. In contrast, No. 54 is a comparative example in which the aging temperature T2 is exceeded, and No. 55 is an aging temperature T2 lower than the comparative example, and the decrease in hardness and the most increase after heat treatment can be seen.约·56~58 of Table 7 is a steel type D of Table 6 which uses the requirements of the steel invention, and the characteristics of the melt temperature Τ2 are variously changed. Among them, No. 56 and No. 57 are aging temperature Τ 2 range (TA ± 10 In the example of the present invention, both of them are hard deformation excellent in dimensional deformation after heat treatment. On the other hand, No. 58 is a comparative example in which the aging temperature T2 is exceeded, and the maximum dimensional deformation rate after heat treatment is increased. No. 59 to 61 of 7 are inspected for the steel type E of Table 6 using the requirements of the steel invention, and the characteristics of the melt temperature T2 are variously changed. Among them, 'Νο·59 and Νο·60 are aging. The temperature T2 range (TA ± 10 ° C) is an example of the present invention, both of which are hard components. The T 1 and the time effect temperature are in accordance with the present invention, and the degree of the scope of the present invention is larger than that of the large-size deformation. The rate of deformation rate is also increased. The composition of the present invention conforms to the T1 and the time effect temperature is high according to the invention, and the composition of the invention has the high degree of conformity with the present τ 1 and the time effect temperature according to the invention, and has a high degree of -63-200831682 Excellent dimensional deformation inhibition after heat treatment. On the other hand, Νο·61 is a comparative example in which the aging temperature T2 is outside the range of the present invention, and although the difference in dimensional deformation ratio after heat treatment is good, the average dimensional deformation ratio and the maximum dimensional deformation ratio are lowered. In addition, No. 62 to 64 of Table 7 are inspected for the characteristics of the steel type F in Table 6 in which the steel component is in accordance with the requirements of the present invention, and the melt temperature τ1 and the temperature T2 are variously changed. Among them, Νο·62 and Νο·63 are examples of the present invention in which the aging temperature T2 is in the range of the present invention (TA ± 10 ° C), both of which have high hardness and excellent dimensional deformation inhibition after heat treatment. On the other hand, in the comparative example in which the No. 64 aging temperature T2 is outside the range of the present invention, the difference in the dimensional deformation ratio after the heat treatment is good, but the average dimensional deformation ratio and the maximum dimensional deformation ratio are lowered. In addition, No. 65 to 67 of Table 7 are inspected for the characteristics of the steel type G in Table 6 in which the steel component is in accordance with the requirements of the present invention, and the melt temperature τ1 and the temperature T2 are variously changed. Among them, No. 65 and Νο·66 are examples of the present invention in which the aging temperature T2 is in the range of the present invention (TA ± 10 ° C), and both of them have high hardness and excellent dimensional deformation inhibition after heat treatment. On the other hand, in the comparative example in which the aging temperature T2 of the No. 6 7 is outside the range of the present invention, the difference in the dimensional deformation ratio after the heat treatment is good, but the average dimensional deformation ratio and the maximum dimensional deformation ratio are lowered. The N 〇 shown below all meet the requirements of the present invention at the melt temperature and the aging temperature, but since the composition of the steel does not conform to the scope of the present invention, -64 - 200831682 produces a comparative example of various disadvantages.

Both No. 68 and No. 69 are examples in which the steel type Η and the steel type I of Table 6 which simulates the conventional high-C high-Cr steel are used, because the product of [Cr] and [C] is large, [Cu] The ratio of [C] is small and the Ms point is very low. Therefore, the average dimensional deformation rate, the maximum dimensional deformation rate, and the dimensional deformation rate after heat treatment are all increased. Further, in the case where these steel grades have a very high tempering temperature, a high hardness can be obtained, so the tempering temperature when the above steel grade is used is set to 510 ° C, and various characteristics are measured.

No. 70 and No. 71 are examples of the steel type J of Table 6 in which the amount of Cu is small, the ratio of [Cu]/[Ni], and the ratio of [Cu]/[C] are small. The decrease in hardness and the increase in the maximum dimensional deformation rate.

No. 72 and No. 73 are examples in which the steel type K of Table 6 having a large ratio of [Cu] and [C] is used, and both have the maximum dimensional deformation ratio. Further, in the present embodiment, although the temporal change of the dimensional deformation ratio is not shown, it can be predicted that the melt processing-aging treatment can be maintained as long as the conditions complying with the requirements of the present invention are performed. High hardness and good dimensional deformation characteristics, and the temporal change of dimensional deformation rate can be suppressed to a small extent. The present invention has been described in detail with reference to the specific embodiments thereof, and it is possible to make various changes and modifications without departing from the spirit and scope of the invention. In addition, the case is based on the Japanese invention patent application filed on October 17, 2006 (Japanese Patent Application No. 2006-28308 8), and the Japanese invention patent application filed on January 30, 2006 (Special Wish 2006--65) - 200831682 2 94 528) and the Japanese invention patent application filed on February 27, 2007 (Japanese Patent No. 2007-047490). Further, all references cited herein refer to the entirety of the document. [Industrial Applicability] The steel for cold working mold of the present invention has a high hardness, excellent dimensional deformation inhibition after heat treatment, and excellent weld repairability, as described above. Therefore, the mold obtained by using the steel for cold working die described above is particularly suitable for use as a molding die for a high tensile steel sheet having a tensile strength of about 5 9 OMPa or more, which can further improve the life, particularly the life after welding repair. Moreover, the manufacturing method of the present invention appropriately controls the components in the steel and the conditions of the melt treatment and the aging treatment, so that the cold working mold having high hardness and excellent dimensional deformation inhibition after heat treatment can be efficiently produced. Use steel. Therefore, the mold obtained by using the production method of the present invention is particularly suitable for use as a molding die for a high tensile steel sheet having a tensile strength of about 5 90 MPa or more, which can further improve the life, especially the life after welding repair. Fig. 1 is a schematic view showing a state in which the base materials are welded to each other by a weld metal; Fig. 1(a) is a cross-sectional view of the welded portion, and Fig. 1(b) is a view of Fig. 1(a) Schematic diagram of the hardness distribution of the A region shown in Fig.-66 - 200831682 Fig. 2 (a) is a state in which JIS SKD11 is used as a steel for a mold, and a "biting phenomenon" occurs on the surface of a mold having a film thickness of TiN. Optical micrographs shown; Fig. 2(b) and Fig. 2(c) are optical micrographs showing a part of the enlarged microscope; Fig. 2(d) is an optical microscope of the mold base before applying the film of TiN photo. Fig. 3(a) is a schematic view showing the shape of φ of the test piece for welding used in the embodiment, and Fig. 3(b) is a cross-sectional view showing the groove portion enlarged. Fig. 4 is a schematic diagram showing the appearance of a test piece after pre-stacking welding. Fig. 5 is a schematic view showing the shape of a Xia's smashing test piece used in the examples. Fig. 6 is a graph showing the relationship between the ratio of [Cu]/[Ni] and the degree of HAZ softening. Figure 7 is a graph showing the hardness distribution curve. Fig. 8 is a graph showing the relationship between the ratio of [Cu]/[C] and the dimensional deformation ratio (average 値, maximum 値). _ Fig. 9 is a schematic diagram showing the effect of aging treatment on hardness and dimensional change (size deformation rate). The first diagram shows the effect of the aging treatment on the amount of dimensional deformation. -67-

Claims (1)

200831682 X. Patent application for Fan Park is in accordance with: 1 · A steel for cold working die, converted by mass %, C: 0.20 ~ 0.60%, si : 〇 · 5 ~ 2.0 0 %, Μ η : 0 · 1 〜 2 %, C r : 3.00 ~ 9.00%, A1 : 〇 · 3 ~ 2.0 %, Cu: 1.00 to 5%, Ni: 1.00 to 5%, Μ 〇: 〇· 5 to 3 % and/or W: 2% or less (including 0%), S: 〇. 1 〇% or less (excluding 0%) ), the following formula (1) to (3) of each element: {] in the formula is the meaning of the content (%). Equation (1) [Cr]X[c]g 3·00, number formula (2) [Cu]/[Ni]·· 0.5 〜2·2, the formula (3) [Mo]+ 〇·5χ [W]: 0·5 ～3.0% Impurity. For steel, the mold is composed of 0%). Said cold 0%). The requirements, and the rest are iron and inevitable 2. The cold working die as described in the first paragraph of the patent application contains V: 0.5% or less (excluding 〇%). 3. The cold-forced steel according to claim 1 or 2, further comprising: at least one element selected from Ti, Zr, Hf, Ta, and Nb' totaling 0. 5 % or less ( Excluded 4. For any of the steels for processing molds in the scope of patent application Nos. 1 to 3, which contain co··10% or less (excluding -68-200831682 5 • as required by patent applications Nos. 1 to 4) Any of the steels for cold working die according to any one of the following, wherein the transition point (Ms point) of the granita iron represented by the following formula: Ms point = 5 5 0 - 3 6 1 X [ C ] - 39 χ [Μη] -35χ [ V ) -20x [Cr] -17x [Ni]-10x [Cu]-5x ([Mo]+[W]) + 1 5x[ Co]+ 30x[ A1] {] is a representative The content of each element (%) is more than 17 ° C. 6. A mold is obtained by using a steel for cold working die according to any one of claims 1 to 5. 7. A method for producing a steel for cold working die, the steel for cold working die being a steel according to the composition component of the first application patent scope, and comprising: the preparation conforming to the following formula (4) [] in the formula [] is the meaning of the content (%) of each element} (4) [Cu] / [C]: the procedure of the steel of the requirements of 4.0 to 15; to satisfy the conditions of the following formula (5) The process of melt treatment and aging treatment; TA-10^ T2^ ΤΑ+ 10 ··· ( 5 ) where TA=0.29xTl-2.63x[Cu]/[C]+ 225, τ 1 is The method of producing a steel for cold working die according to claim 7, wherein the steel system contains the aging temperature (°C). V : 0 · 5 % or less (excluding 0 %) ° The method for producing a steel for cold working die according to the seventh aspect of the invention, wherein the steel system contains at least one element selected from the group consisting of Ti, Zr, Hf, Ta, and Nb. The total is 0.5% or less (excluding 0%). The method for producing a steel for cold working die according to any one of claims 7 to 9, wherein the steel system contains Co: 10% or less (excluding 〇%). The method for producing a steel for cold working die according to any one of claims 7 to 1, wherein the transition point of the granulated iron (Ms point) represented by the following formula: Ms point =550-361x(C) -39x[Mn] -35x(V] -20x[Cr] -17x[Ni]-l〇x[Cu]-5x([M〇]+[W]) + 1 5x[ Co]+ 30x[ A1] is a temperature of 170 ° C or more. i 2. The mold is a method for producing a steel for cold working die according to any one of claims 7 to 11. ^-70-