TW200842194A - Hot working die steel for die-casting - Google Patents

Abstract

To provide a hot-working tool steel for die casting, excellent in heat-check resistance and capable of sufficiently restrain the crack from a water-cooling hole. The hot-working tool steel has the composition composed, by mass%, of 0.1-0.3% C, 0.1-1.5% Si, 0.3-2% Mn, 6-12% Cr, -0.05% P, -0.01% S, 1-3% Mo, 0.5-1.5% V, 0.005-0.025% s-Al, 0.005-0.025% N, -0.005% O and the balance Fe with inevitable impurities, and this steel is tempered at a low temperature of -500 DEG C after quenching to be used.

Description

200842194 IX. Description of the invention: [Technical field to which the invention belongs] The invention is related to the heat display made by the mold of the series; the detailed description of the water-cooled hole which is the main cause of the large-scale rupture of the scale of the scale of the dragon is caused by The high cycle of the die-casting product manufacturing (highcycl phase ~ hot wedge steel. The hot die steel for die casting of the present invention is especially suitable for use as a material for aluminum die casting mold. [Prior Art] In Yu Mingli casting mold, f knows There is a problem of thermal cracking caused by thermal fatigue on the cavity surface. This "thermal crack" refers to the cavity when the cooling water is poured into the cavity surface after the mold is opened. The rapid cooling of the surface and the temperature difference between the inside and the heating state cause tensile stress on the cavity surface, and the thermal fatigue caused by repeating the situation causes cracks on the cavity surface. For this thermal crack, the mold is improved. Hardness will be advantageous. # Another π aspect, in recent years, there has been a demand for shortening the manufacturing cycle of aluminum die-casting products (recycling). To achieve this goal, the purpose of shortening the clamping time of the mold is to increase The tendency to water-cool the aluminum cast product in the mold is enhanced by the water/cold, in particular, by bringing the water-cooled hole close to the cavity surface. In this case, the surface of the water-cooled hole is formed during the casting of the aluminum product. The generated thermal stress will increase, and the phenomenon of cracking from the water-cooled hole will cause problems. The cracking caused by the water-cooled hole is not only caused by the thermal stress of the repeated load during die-casting, but also caused by the cracking of the thermal stress. 312 Χ / 发明 发明 发明 发明 发明 发明 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 Χ Χ Χ Χ Χ Χ Χ Χ Χ Χ Χ Χ Χ Χ Χ Χ Χ Χ Χ Χ Χ Χ & & & & & & & The easier it is to produce the mouth, the fracture caused by the water-cooled hole is advantageous in reducing the hardness of the mold. 'That is, the hardness of the mold is favorable for the hot crack, but it is disadvantageous for the crack generated from the water-cooled hole; Reducing the hardness of the mold is advantageous for the cracking from the water-cooled hole, but it is unfavorable for the hot crack, and the heat crack resistance is deteriorated. The viewpoint of suppressing the crack generated from the water-cooled hole is considered. It is preferable to make the hardness of the mold to be HRC 45 to 40. As a current aluminum die-casting mold, a 5Cr-based or hot-die steel represented by JIS-SKD6i is mainly used. In recent years, in order to suppress the occurrence of the cavity surface. The thermal crack begins to increase its hardness, and with the high circulation of the manufacture of the pressure-changing product, the risk of cracking (4) from the water-cooled hole of the mold increases. In the case of the above JIS-SKD61, it contains 〇· 4% or so of c, the hardness in the quenched state is, for example, the degree of HRC 53. Therefore, in order to suppress the cracking from the water-cooled hole, in order to reduce the hardness of the bowl to 45 or less, it is necessary to carry out a high temperature of 6 ah or more. Fire. However, if tempering is performed at such high temperatures, the resistance of the steel is lowered. 9 ^ This material contains about 5% of Cr' which is originally a good material. However, if tempering is carried out at a high temperature of 60 or higher, the contained c will be tempered at a high temperature and precipitated in the form of Cr carbide, so that the Cr contained in r can no longer contribute to the improvement of rhythm resistance. Nowadays, the hot die steel which is mainly used as an aluminum die-casting mold with jis_s Η Η 312XP/invention specification (supplement)/96-08/96114961 6 200842194 = can not solve the problem of cracking from the water-cooled hole well. On the other hand, the problem of cracking from the water-cooled hole and the problem of the cavity surface and the clothing mark are considered to prevent the rust generated in the water-cooled hole and reduce the hardness inside the mold in which the water-cooled hole is located. It is effective to increase the hardness of the cavity surface of the mold which produces and thermally crack. However, there is no material which can satisfy these characteristics. However, the invention disclosed in the following reference is The inner diameter surface of the water-cooled hole is made to have a lower hardness than the surface of the mold, so as to take into consideration the prevention of cracking of the water-cooled hole and the heat-resistant cracking of the surface of the mold. The steel disclosed in the reference 1 is used by the former. JIS-SKD61 After quenching and tempering and quenching to a higher hardness, the surface of the water-cooled hole is tempered by induction heating, burner heating, laser heating, etc. to a localized lower hardness. Among the ones disclosed in i, the method must be locally heated, and the water-cooled aperture must be made into a size that the burner can enter, and the shape of the water-cooled hole must be limited. [McChao 1] Japan SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the invention to provide a hot die steel for die casting which is excellent in heat-resistant crack resistance and can suppress cracking from water-cooled holes. The inventors have conducted intensive studies on the above problems, and as a result, have found that the above problems can be solved by the following hot die steel for die casting. The present invention has been completed. 312XP/Invention Manual (Repair)/96-08/96114961 7 200842194 The gist of the invention is as follows: 1 · A hot-pressed copper for die-casting, 焱 焱 at 50 (TC below the temperature to temper; the J is described as: after the steel quenching '% by mass C: 0. 1~〇. 3 %, clothing, The component is contained in

Cr : 6 to 12%, P: 0.05% · 1 65%, Mn . 0.3', 〇.5 〜 i, 〇, "i: 0.005 n 〇 1 / ° or less, Mo: 1, v: 〇嶋The following, the remaining We and the unavoidable impurities. 2. For the die-casting hot-mould steel of item 1, it is more selected from Mi: 2. 〇% below η Γ 碉 Berry% at least one. 〇/◦ 3. Among the groups below and below, 3. For the die-casting hot-die steel of item 1 or 2, the amount of Co is 5% or less. Each of the other μ-beans 4·such as the items 1 to 3 of the die-casting Further, at least one selected from the group consisting of Ti: U% or less, Zr: 0.2% or less, and I Nb · 0.2% or less by mass% is used for the die casting of the present invention. In the hot-die steel, the content of c is reduced, and the content of Cr and Mo is increased, and the amount of Cr is increased. Therefore, when used as a die-casting mold, cracking from the water-cooled hole can be effectively suppressed, and The die-casting mold has excellent heat-resistant crack resistance. The hot-die steel for die-casting of the present invention is particularly preferably used as a material for an aluminum die-casting mold.

Cr is known as an element for improving corrosion resistance. However, in the case of the usual JIS SKD61, when the hardness is used to temper, it is necessary to temper in the south/near of 6 〇〇 or more, so that the cr for improving the financial property is precipitated by carbide, and the effect is obtained. Almost lost. On the other hand, if the tempering temperature is reduced to the extent that the carbide 312XP/invention specification (supplement)/96-08/96114961 c 200842194 does not precipitate, the hardness will become very hard 5 hrs or more, and it is used as a die casting. When a mold is used, breakage from a water-cooled hole is likely to occur. x, and of course, by reducing the C content, tempering at a low temperature of 50 (rc or less) can serve the hardness of the target. However, in this case, the hardness of the cavity surface is also lowered, which may cause deterioration of heat-resistant crack resistance. In the hot-formed steel for die-casting, the amount of c is reduced while the amount of c is reduced. By reducing the C content, low temperature tempering at 50 (rc or less) is difficult to occur. The hardness of the water-cooled hole is less than or equal to the hardness of HRC 45. In addition, the straw is added with an appropriate amount of Mo, and when used as a mold for die-casting, the heat from the solution (for example, the inscription liquid) during the die-casting can be used to make the cavity of the prayer cavity. Partially, hard. In particular, the Mo added is used in the casting of die-casting products: the surface of the cavity is heated by the heat of the melt (in the case of (4) liquid, it is 6 0 0~6 5 0 °C) and carbide scraping the mountain.", the paradigm type precipitation, can be used to make the cavity surface partially, that is, the die casting of the present invention, the chessboard, has the hardness of the cavity surface in the surface mode In use, it is hardened by age hardening. The effect is that the thermal crack of the cavity surface can be well suppressed. That is, the die casting mold for the die casting of the present invention can be skillfully utilized for use as a mold for die casting by using a liquid from the V liquid. The phenomenon of heat-induced aging of the cavity surface can result in a mold with a lower internal hardness and a lower hardness, while the cavity surface locally increases the hardness of the mold. This is the die casting of the present invention. Hot mold steel 312XP / invention manual (supplement) / 96·08/96114961 9 200842194 has a better effect than the conventional one. 夕本=1' / is the rhyme-resistant element of the amount of Cr added 1 夕., :中中,Cr, which is added to the low temperature after the quenching treatment, does not precipitate as carbides, but is solid-melted in the shape of the core to effectively improve the corrosion resistance of the steel. By using the hot-formed steel of the present invention as the pressure __, the rust of the water-cooled hole can be suppressed, and the crack caused by the stress corrosion of the rust and the cold hole can be satisfactorily suppressed. t 目士's use of the hot die steel for die casting of the present invention as a die casting (four) die The cavity surface of the caster mold is hardened by secondary hardening (aging hardening) by Mq carbide precipitation to a hardness of 45, which can ensure heat crack resistance. /, two people, in the present invention The reason for the limitation of each chemical component is as follows. In addition, in the following, "%" means "% by mass". c · 0. 1-0. 3% C is an important hardness and wear resistance in ensuring the performance of the mold. It is an essential element of the damage. It is about 0.4% of C in the normal hot-form steel. In the present invention, in order to obtain a hardness of HRC45 or less at a low temperature tempering of less than TC, the content of c is higher than usual. The mold steel is low, and the range is 0.1 to 0.3%, preferably 〇·15 to 0.25%.

Si ·· 〇· 1 ～1 · 5%

Si is an essential element as a deoxidizing element in steel making. 312XP/Invention Manual (supplement)/96-08/96114961 10 200842194 Two=1?, the amount 'can improve the machinability and temper softening resistance. When the range is set to be large, the grading property is lowered, so that the target target enthalpy is 0.1 to 15%, preferably 0.1 to 0.5%. Μ : 〇 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 The impact value is reduced, or the method is reduced, so the upper limit is set to 2%. Also, the second degree of Mn is not set to be U. Add the upper limit of 1 to Μη

Cr : 6-12%

Cf is an element which improves the hardenability and improves the resistance of the water-cooled pores. In order to obtain an effect of improving the resistance to the button, it is preferable to add 6% or more to 8% or more. However, if added in a large amount, the phase softening property will be lowered and the mold performance will be lowered. Therefore, it is limited to 2%. y Γ 士 - - The upper limit is 12 gongs, and the upper limit of the Cr content is preferably 10%. P ·· S 0· 05% Since the P element will lower the impact value, it is preferable to reduce the content of the P element. When it is inevitable to contain it, it is preferable to reduce it to 〇 5% or less. , S : ^0. 01% Since 兀S will form MnS and reduce the impact value, it is better to reduce the amount by one. /, in case of inevitable containment, it is better to reduce to below o ou. 312XP/Invention Manual (supplement)/96-08/96114961 π 200842194

Mo ·· 1 to 3% Since Mo forms carbides, it enhances the substrate strengthening and wear resistance, and is essential for ensuring hardenability. Further, when the hot die steel for die casting of the present invention is used as a die for die casting, the carbide of Mo is precipitated by heat from the melt (in the case of aluminum melt in the vicinity of 6 ° C), so that the mold is molded. Increased hardness. In the present invention, in order to prevent cracking from the water-cooled hole, the hardness of the mold after quenching and tempering is set to be lower than HRC 45, and the temperature of the cavity surface is increased in the die casting (in the case of aluminum melt, 60 (rc) In the vicinity, the hardness of HRC45 or higher can be obtained, and the heat crack resistance can be improved. In order to obtain such effects, it is necessary to add 1% or more, and it is preferable to add i 5% or more. · Since the effect is saturated, it is not economical (10) Further, the upper limit of the amount of Mo added is set to be equal, and even if it is excessively added, the upper limit of the addition amount is preferably set to 2 · 5 %. v ·· 〇· 5~1· 5% can enhance the enhanced V element By forming carbides during tempering, the base material is precipitated, and the wear resistance is improved. When fine particles are formed in the form of particles, the effect of suppressing the crystallization is suppressed and the impact value is suppressed from being lowered. It is necessary to add 0·5% or more. Decanter, and reduce the initiality, so the upper limit is U and the upper limit of the ice plus is set to 1%. 2XP/Invention Manual (supplement)/96- 08/96114961 12 200842194 〇· 005 ～〇· 025% AJ 凡素 is in addition to In addition to the effect of the continuation of the steel in the steel (4) nitrogen (four) gas element, the crystal grains during the quenching heating are coarsened, and the fine dispersion is allowed to be suppressed: to obtain such effects, it is necessary to add 0.005% or more. Even if the excess is added, it is set to 0.025%. The effect has reached saturation, so the upper limit Ν: 〇. 005-0. 025% Ν will be with the steel in the Α 1 and V bond social affairs - 耑立立丨& The bank and the mouth form a telluride, and the crystal grains are coarsened by heating with a finely divided fire. In order to prevent the impact value from being lowered, it is necessary to add 0.005% or more in order to obtain such effects, and 'even if it is excessively added' The effect has reached saturation of 〇·025%. 上丨良疋0 : ^ 005% 〇 will form an oxide system to reduce the impact value. To suppress the reduction of the impact value, the yttrium content must be 〇. 〇〇 5% the following.

Ni : $2%, CuS 1% Νι and Cu are effective for improving the hardenability and strengthening the substrate, and can be added as needed. However, even if the excess is added, since the effect is saturated, it is disadvantageous in terms of economic efficiency, so the upper limit is set to 2% and 1%, respectively.

Co : ^5%

Co is an element that increases strength by solid solution strengthening and can be added as needed. 312xp/Invention Manual (Supplement)/96-08/96114961 13 200842194 However, even if it is added excessively, since the effect is saturated, it is economically disadvantageous, so the upper limit is set to 5%.

Ti ·· $ 〇· 2%, Zr ·· $ 〇· 2%, Nb ·· S 0· 2% These will form Ti(CN), Zr(CN), Nb(CN) and these composites The carbonitride is finely precipitated, and is an element which can prevent coarsening of crystal grains during quenching and heating. In order to refine the crystal grains to ensure the toughness, it may be added as needed. However, if the excess is added, the coarse carbonitride is crystallized during solidification, and the impact value is lowered, so the upper limit is set to 0.2%. Further, in the case of such a composite addition, the total amount thereof is preferably 5% or less. [Embodiment] Next, embodiments of the present invention will be described in detail below. Hereinafter, the present invention is exemplified by the steel of the present invention and comparative steel, but it is needless to say that the present invention is not limited thereto. The knife melts the various steels shown in Table 1 in a 15GKg vacuum high frequency induction furnace to make the ingot (ing0t) s 12〇 (the TC is forged into a 60x60mm section angle bar. The angle bar is cut into 5 〇〇mm length, heated to oil bath quenching. Say this w then 'tempering 2 times under 45Gt: xl hours. For each horn that performs tempering' measure 1/4H part (surface and center One-and-a-half of the hardness of the part, and the Charpy impact test of the width direction of the τ ° angle bar of the 2 mm U notch test piece, and from 1/4 Η 312 ΧΡ / invention specification (supplement) / 96 -08/96114961 χ 200842194 7 Cut the l〇Xl〇xl〇mm block, grind the surface with sandpaper, and immerse it in the water for 24 hours to confirm the resistance test. 4U Corrosion Evaluation Those who have not experienced rust are used as "〇", and those who have rust are evaluated as "X". 1 ^ For the simulation to carry out (4) Casting of the cast product, the hunter is heated by the frequency from room temperature to 65 (rc4 sec 乂 1 cycle) , for the above-mentioned tempering at 45 (rc), the water is cooled as 1 000 cycles, and the subsequent surface is measured. +. Repeatedly, the above evaluation results are shown in Table 2. 312XP/Invention Manual (Supplement)/96-〇8/96114961 15 2 8 [5 φ| Surface c Other Wide* »»H Ni : 0. 5 %, Cu : 0. 5% οα θ <d> ·»~Η 3: LO cz> d • rH θ Zr: 0.1°/〇, Nb: 0.1% Co : 1%, Zr : 0.2%, Nb : 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.012 0. 022 0.008 0.005 0.008 0. 011 0.009 1 0.021 I 0.023 | I 0.018 | 1 o.oii 1 | 0.015 1 0.012 0.011 0.011 rH Q rH o 0.009 0.009 0.008 0. 007 0.002 0.009 0.012 s-Al 0.015 0.005 0.008 0.013 0.022 1 0.021 ;0.018 1 0.011 1 | 0.016 | 0.021 0.022 0.018 0.019 0. 021 0.021 0. 019 0.015 0. 003 0.012 0.012 CD > CO CD OO <3> rH t~H CD CD OO CD CO cz> CZ5 CO C3 LO LO o rH CO 〇03 CO o LO CO o CO o rH CJD cz> CO CD t-H CO ci CO cz> CO o CO c=5 CO <z? CO o Bu G) CO o LO OO o 〇od LO CM* CNI OO cvi CO T-< OO rH CO od LO csi OJ oi CO csd LO oi CO cvi CO 03 LO (Ni inch LO oi LO od CO oj inch oi CO 〇 inch oi CO <ΝΪ CO Oi (NI tH ci3 οα od CD CO t-H t-H m CO i-H CD H OO od oa ai 05 in 10.1 05 od CO od H ai (NI cri cn> od r-H 05 LO CO 05 rH 7 · CO cri LO LO 00 0. 002 0.002 0. 005 0.008 0.009 I 0.001 1 I 0.002 | ! 0.002 | 0.002 | 1 o.ooi I 1 o.ooi 1 I 0.002 II 0.002 | I 0.002 0.002 0.001 S 0.001 0.002 0.002 0.002 0.002 0.001 0.001 0. 001 Oh 0.008 0.012 rH cz><=> 0.024 | 0.003 | I 0.018 II 0.009 I 1 0.003 1 I 0.007 II 0.031 II 0.021 1 0.015 0.011 0.012 0.011 0.012 0.011 0.012 0.009 0.011 0. Oil 0.012 0 Oil 0.011 Od inch d LO inch CD OO ◦ oa rH CD rH LO LO ◦· CO LO CO o CD (N1 LO 〇OO Q· LO inch C=> LO L〇LO LO LO inch CZ5 ο OO inch c rH LO ζ=>C<I LO o CO omo 1—( 〇· CO ◦· L〇cz> CO C3 CO CD CO rH CO G> LO CV1 <〇CO ◦· 03 C<I CD 0.25 I (NI CD CD CNI CNI <=&g t; (NI CD cd 0.22 r-i oa ◦· LO CNI C3 CNI <NJ o CO CD 0. 29 〇cva 1—H CD CNI ◦· OO CD CO C<1 CD OO CNI cz><NIcz> CNI CD π 〇· OO CD 1 0.22 1 OO ◦· S 0. 38 03 〇OO 〇· (NI CD OJ o <=> rH CZ5 o oa <=> t-H ot-H Od C3 2 〇· 0. 38 差·rH oa CO L〇CO OO CD ◦ tH rH rH 03 J〇o (D Mi b〇JG •rH ·*—i 1 11 i B soil jl3 restaurant 綦 钢 91 91 91 196 inch 1196 /80-96/(分}«)_^缩^Change to taste 2 £ 200842194 [Table 2]

No. 450 °C tempering 650 ° C after repeated heating hardness (HRC) hardness (HRC) impact value (J / cm2) and the name of the insect 1 40 52 〇 46 2 42 48 〇 48 3 41 50 〇 46 4 43 46 〇49 hair 5 44 45 〇48 Ming 6 42 48 〇47 steel 7 42 48 〇48 8 42 49 〇47 9 41 50 〇46 10 43 48 〇48 11 41 48 〇47 a 36 58 〇42 b 53 21 〇48 c 42 25 〇48 d 42 23 〇48 e 42 18 〇47 than f 42 15 〇48 compared to g 42 49 X 48 steel h 42 21 〇48 i 42 48 〇44 j 42 32 〇47 k 41 33 〇47 1 42 28 〇48 m 40 30 〇48 知知钢 A 53 18 X 47 氺 and t 〇 〇: not rusted X: rust 312XP / invention manual (supplement) /96-08/96114961 17 200842194 points again, will After the invention steel No. 2 of Table 1 was heated to 1〇3 (rc, oil bath: bonfire, tempering twice under 4501 x l hours, and heating with Shigang A to 1〇30 C For oil bath quenching, tempering 2 times under conditions of 45〇7 X〗=, and will be known as A steel. (5) Those who temper 2 times under the conditions of Guangzhi; Breaking The resistance to delayed damage of the index of sensitivity is evaluated here, and the evaluation of the delayed damage resistance is performed as follows: 邙:: 1 has a test piece of 环状. 1R annular cut (n〇tCh) Incision 邛 drops industrial water (used to make the relationship between the folks. 匕生绣) '5 weeks to check the flexural stress and failure J Joshi, the flexural stress (G hour rupture stress) and 200 ~ crack stress The ratio of 'the resistance to delayed damage is evaluated. The ring is cooled to 65 () ° C for 4 seconds, followed by water cooling as 1 cycle, I, repeated 10 0 〇〇〇 cycle after the trace length m or thermal cracking on the surface of the heart The length is known as an index of heat-resistant cracking. The above 5 flat mussel results are shown in Table 3. Above and Table 3, the target value of the delayed-resistance characteristic is set to 0.7 to 312XP/invention specification (supplement) )/96·〇8/96114961 18 200842194 [Table 3]

No, tempering temperature (°C) hardness (HRC) heat crack resistance resistance to delayed failure characteristics maximum thermal crack length (^ m) 200 hours fracture stress ratio 2 450 42 120 0. 98 A 450 53 123 0. 65 L 630 42 253 0. 91 As shown in the results of Table 2, the inventive steel No. 1 to No. 11, the hardness of HRC 40 to 44 at 450 ° C tempering, and the hardness after repeated heating at 650 ° C is HRC46~49, that is, the hardness is improved. Further, since the Cr carbide was hardly precipitated at a low temperature of 450 ° C, either of them showed good profitability. In contrast, compared with steel C, which is 0. 05%, it is lower than the lower limit of 0. 1% of the present invention. Therefore, the hardness in tempering at 450 °C is only HRC36, and the hardness after repeated heating at 650 °C. It is also a lower HRC42 with poor heat-resistant cracking. On the contrary, the C of the comparative steel b is 〇·38% higher than the upper limit of the present invention 〇·3%, and therefore, the hardness after tempering at 450 °C is as high as HRC53, and the impact value is low. The Si content of the comparative steel c was set to 2%, which was higher than the upper limit of the present invention by 15%, and the impact value was low. The Μη of the comparative steel d contains 1 at 2.5%, which is higher than the upper limit of 2% of the present invention, and the impact value is low. The content of the impurity Ρ of the comparative steel e is 〇·〇8%, which is higher than the upper limit of the present invention of 0.50%, so the impact value is low. Further, the content of the impurity S of the comparative steel f is 〇 5%, which is higher than the upper limit of the present invention of 0·01%, so that the impact value is low.

The Cr content of the comparative steel g is 51%, and the lower limit of 6% of the present invention is low, so the corrosion resistance is low. 312XP/Invention Manual (Supplement)/96-08/96114961 19 200842194 On the contrary, the Cr content of Comparative Steel 11 is 13.5%, which is higher than the upper limit value of 12% of the present invention, so the impact value is low. The Mo content of the comparative steel i was 〇 6%, which was lower than the lower limit of 1% of the present invention. Therefore, even if the heating at 650 ° C was repeated, the hardness could not be sufficiently improved. It shows that the heat crack is not good. The V content of the comparative steel j is 〇·3%, which is lower than the lower limit value 〇·5% of the present invention, so that the coarsening of the crystal grains occurs, and the impact value is low. The content of s A1 is 〇〇〇3% than that of the ruthenium steel k, which is lower than the lower limit value 〇· 005% of the present invention, so that coarsening of crystal grains occurs, and the impact value is low. The N content of Comparative Steel 1 is 〇·〇〇2%, which is lower than the lower limit value 〇 5% of the present invention. Similarly, coarsening of crystal grains occurs, and the impact value is low. One is better than the 0 of the fortune steel § The amount is 〇· Compared with the upper limit of the invention 〇· Gw% South, therefore, the amount of the medium is increased, and the impact value is low. Its -man, the known steel shovel is jis-SKD61, its hardness under tempering at 450 °C is HRC53, and the hardness after repeated heating at 650 °C is reduced to HRC47. And the resistance to the surname is also poor. Secondly, in Table 3, the hardness of the invented steel Ν〇·2 at 45 〇t: is low, but it is equivalent to the heat-resistant crack of the conventional steel A245 (rc fire-retardant material with high hardness). Sexuality and excellent resistance to delayed damage. Furthermore, compared with the conventional steel A in 63 (compared to the same hardness of high temperature tempering under rc), since it is tempered at a low temperature, it has high resistance to flexion and heat cracking. It is also excellent. ..., ^ As described above, it is known that the invention steel system has the characteristics of suppressing the cracking from the water-cooled hole in the past and the heat-resistant cracking property. </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> </ RTI> <RTIgt; It is to be understood that the various changes and modifications are within the scope of the invention. The invention is based on the Japanese Patent Application No. 2005-346156 filed on Nov. 30, 2005, the disclosure of /Invention manual (supplement)/96-08/96114961 21

Claims (1)

200842194 X. The scope of application for patents: 1 · A hot-moulded steel for ink casting, whose conversion and retention are based on quenching the steel containing the following components at 50 (TC below TC... It is obtained by tempering; the component contained is in mass%: C: 0·1~〇·3% Si: 0. 1-1. 5% &gt; Μη : 0·3~2%, Cr: 6~12%, P: 0·05% or less, S: 0.01% or less, Mo: 1 to 3%, V: 0·5~1. 5%, s-Al: 〇·〇〇5~0 ·025%, N: 0·005~0· 025%, 0: 0·005% or less, and the rest are Fe and unavoidable impurities. 2 · The binding of the first item of the patent application range is % by mass. Free Ni: 2% or less, and Cu: 1% or less, hot mold steel, which is at least one of the group formed by the step/step. 3. The die casting according to item 1 of the patent application contains Co in mass% : 5% or less. With hot-mould steel, it is further advanced / step 4 · For example, the hot-mould steel for die-casting in the second paragraph of the patent application, the further step / 312XP / invention manual (supplement) / 96 Na 96 丨 1496 j 22 I 200842194 Contains Co in mass %: 5% Further, 5. The hot-formed steel A for die-casting according to item 1 of the patent application is selected from the group consisting of 'Ti: 〇·2% or less, zr: 0.02% or less, and Nb: 〇 · at least one of the group consisting of 2% or less. Further. 6. The die casting according to the scope of application of the patent item ,2, containing, by mass%, selected from ^ X· Ti : 〇 · 2% or less, h : 〇· 2% or less, and at least one of the group consisting of Nb: 〇·2% or less. Further, the die casting of the third aspect of the patent application is in a mass% selected from: 0.2% or less, Zr: at least one of 〇·2% or less and Nb: 0·2% or less. Further, 8. The hot-mould steel for die-casting according to item 4 of the patent application, • containing % by mass Select at least one of r Ti : 〇 · 2% or less, Zr : 〇 · 2% or less, and Nb : 〇 · 2% or less. 312XP/Invention Manual (supplement)/96-〇8/96114961 23 200842194 VII. Designated representative map: (1) The representative representative of the case is: No (2) The symbol of the representative figure Single explanation: None 8. If there is a chemical formula in this case, please disclose the chemical formula that best shows the characteristics of the invention: None 312XP/Invention Manual (Supplement)/96-08/96114961 4