TW201207128A - Structural stainless steel sheet having excellent corrosion resistance at weld and method for manufacturing same - Google Patents

Abstract

Disclosed are: a structural stainless steel sheet which can be highly efficiently produced at low cost and has excellent corrosion resistance in a welded part; and a method for producing the structural stainless steel sheet. Specifically disclosed is a structural stainless steel sheet which contains, in mass%, 0.01-0.03% of C, 0.01-0.03% of N, 0.01-0.40% of Si, 1.5-2.5% of Mn, 0.04% or less of P, 0.02% or less of S, 0.05-0.15% of Al, 10-13% of Cr, 0.5-1.0% of Ni, and 4 (C + N) or more but 0.3% or less of Ti, while controlling V to 0.05% or less, Ca to 0.0030% or less and O to 0.0080% or less. The structural stainless steel sheet is further characterized in that the F value obtained by Cr + 2 Si + 4 Ti - 2 Ni - Mn - 30 (C + N) is 11 or less, the FFV value obtained by Cr + 3 Si + 16 Ti + Mo + 2 Al - 2 Mn - 4 (Ni + Cu) - 40 (C + N) + 20 V is 9.0 or less, and the balance of the structural stainless steel sheet is made up of Fe and unavoidable impurities.

Description

201207128 VI. Description of the Invention: [Technical Field of the Invention] The present invention relates to, for example, a body material for a truck (rail wag〇n) which is a coal or an iron ore. A structural stainless steel sheet having excellent corrosion resistance and a method for producing the same. [Prior Art] Stainless steel is used as a vehicle body material for a coal or iron ore truck (rail wagon). The mined coal contains a large amount of sulfur content, so the material used for the body of the railway wagon is required to have sulfur corrosion resistance (su 1 fatec 〇rr 〇si ο nresistance), especially the crystal of the welded part. Intergranular corrosion resistance 0 A stainless steel having corrosion resistance and weldability is, for example, a Ti-containing ferritic stainless steel excellent in weld toughness disclosed in Patent Document 1. However, in the technique of Patent Document 1, since the welded portion component is designed as a ferrite phase, there is a problem that the toughness and the corrosion resistance of the welded portion are insufficient. On the other hand, Patent Document 2 and Patent Document 3 disclose that a high-strength phase fraction is controlled, and an appropriate amount of a martensitic phase is generated in the welded portion to improve the workability and resistance of the welded portion. Corrosive technology. Further, in Patent Document 4, a stainless steel which is suitable for a welding method using carbon dioxide gas is disclosed. Further, 'one of the present inventors' first proposed a stainless steel plate for construction using a parameter which can correctly predict the structure of the welded portion and which is improved by the composition of the composition to improve the corrosion resistance of the welded portion (patent Document 5). [PRIOR ART DOCUMENT] [Patent Document 1] Japanese Laid-Open Patent Publication No. Hei. No. Hei. No. Hei. [Patent Document 4] Japanese Patent Laid-Open Publication No. JP-A-2002-280850 [Patent Document 5] JP-A-2009-280850, SUMMARY OF INVENTION [Problems to be Solved by the Invention] However, the techniques disclosed in Patent Documents 2 to 5 The review on the most appropriate range of ingredients is not sufficient. In particular, these documents have hardly seen any considerations for manufacturability, and in the slab stage there is significant cracking and the generation of so-called scab surface defects. It is difficult to avoid the cost rise caused by a decrease in the yield ratio. The present invention has been made in view of the above problems, and an object of the present invention is to provide a stainless steel -6-201207128 plate for structural use which is inexpensive and efficient to produce and has excellent corrosion resistance in a welded portion. [Means for Solving the Problem] One of the inventors of the present invention is to solve the above problems - to concentrate on the results of the research, as long as the chemical composition, especially the content of Mn, Ti, and the balance of each component are adjusted. In the appropriate range, it is possible to suppress the intergranular corrosion caused by the lack of Cr near the grain boundary, and the actual knowledge of the microstructure of the welding heat affected part with the martensite as the main body. The parameter (F値) shown in Patent Document 5. Further, the present inventors have based on such knowledge, in particular, the results of the detailed review on the continuation of manufacturability, except that an appropriate amount of A1 is included and V, Ca, and Ο are lowered below a predetermined range, and FFV is set. In the appropriate range, as a new parameter showing the goodness of manufacturability, it has been found that a cast slab (surface defect) which can significantly reduce the slab crack and the cause of the intermediary, and the present invention has been completed. In other words, the present invention provides a stainless steel sheet for structural use having excellent corrosion resistance in a welded portion, which is characterized by containing mass%, C: 0.01 to 0.03 %, N: 0.01-0.03%, Si: 0.10 to 0.40%, and Mn: 1.5-2.5%., P: 0.04% or less, S: 0.02% or less, A1: 0.05 to 0.15%, Cr: 10 to 13%, Ni: 0.5 to 1.0%, Ti: 4x (C + N) (however, C and N are expressed by the content (% by mass) or more and 0.3% or less, and are limited to V: 0.05% to -, ca.: 0.0030% or less, 0: 0:0080% or less, and the following F値 and FFV値 represented by the formula are composed of F値S 1 1 and FFV 値S 9.0, and the residual portion is Fe and unavoidable impurities. 201207128 F値=C r + 2XS i+4XTi-2XNi -Μη - 3 Ο X (C + N)

FFV値=C r + 3XS i+16XTi +Μο + 2 ΧΑ1— 2 ΧΜη-4 X (Ni+Cu) -40Χ (C + N) +20XV However, in these equations, each element symbol is the element Content (% by mass). Further, the present invention provides a stainless steel sheet for construction which is excellent in corrosion resistance of a welded portion, and which comprises a component having a mass % of Cu: 1.0% or less in addition to the above components. Moreover, the present invention provides a stainless steel sheet for construction which is excellent in corrosion resistance of a welded portion, and which comprises a component having a mass % of Mo: 1.0% or less in addition to the above components. Further, the present invention provides a method for producing a stainless steel sheet for construction, which is characterized by containing mass%: C: 0_01 to 0.03 %, N: 0.01-0.03%, Si: 0.10-0.40%, Μη: 1.5 to 2.5%, Ρ : 0.04 % or less, S: 0.02% or less, Α1: 0·05 to 0·15%, Cr: 10 to 13%, Ni: 0.5-1.0%, Ti: 4x (C + N) (however, C, N is not less than the content (% by mass) or more, and is not more than 0.3%, and is limited to: V: 0.05% or less, Ca: 0.0030% or less, and 〇: 0.0080% or less, and F値 expressed by the following formula FFV値 meets F値S 11,? ?乂$9.0, will have a residual? 6 and the slab of the composition of the unavoidable impurities is heated to a temperature of 1100 to 1 300 ° C, and heat of hot rough rolling containing at least one or more compression ratios of 30% or more is performed in a temperature region exceeding 1 000 ° C. After rolling, and after the above hot rolling, the hot rolled sheet is not annealed but is annealed at a temperature of 600 to 1 ° C and then subjected to pickling 201207128 F値=C r+2XSi+4XTi-2XNi —Mn-30X (C + N)

FFV値=C r + 3XSi + 16XTi +Mo + 2 XA1-2 XMn — 4 X (Ni+Cu) -40X (C + N) +20XV However, in the formulas, the symbol of each element is the element Content (% by mass). Moreover, the present invention provides a method for producing a stainless steel sheet for a structure excellent in corrosion resistance of a welded portion, which comprises, in addition to the above components, a component having a mass % of Cu: 1.0% or less. Further, the present invention provides a method for producing a stainless steel sheet for construction which is excellent in corrosion resistance of a welded portion, and which comprises, in addition to the above components, a component having a mass % of Mo: 1.0% or less. [Effect of the Invention] According to the present invention, it is possible to obtain a structural stainless steel sheet having excellent corrosion resistance in a welded portion, for example, as a vehicle body material for a truck (railway truck) for transporting coal or iron ore. [Embodiment] Hereinafter, the present invention will be described in detail. First, the composition of the components of the present invention. In the following description, % is expressed as mass%. -9- 201207128 • N : 〇.〇1~0.03 % c and N are required to contain 0.01% or more as the necessary strength for structural stainless steel sheets. On the other hand, when the content of C and N exceeds 0.03%, it is easy to precipitate Cr carbide or cr carbonitride, which lowers the corrosion resistance, especially the corrosion resistance of the welded heat-affected zone. In addition, the hardening of the welded heat affected zone also reduces the toughness. For this reason, the contents of C and N are all set in the range of 0.01 to 0.03%. It is preferably in the range of C0.015 to 0.025% and N0.012 to 0.02%. • Si : 0.10-0.40%

Si is an element used as a deoxidizer, and must have 0.10% or more in obtaining the effect. On the other hand, when the content exceeds 0.04%, the toughness of the hot-rolled steel sheet is lowered. Therefore, the Si content is set in the range of 0·10 to 0.40%. The lower limit is 0.02%, and the upper limit is 0.30%. Mn: 1.5 to 2.5% Μη is a deoxidizing agent, and is a useful element for ensuring the necessary strength as a stainless steel plate for structural use, and is also a high-temperature Voss. Tian Iron Stabilization Element. Further, the present invention is an element which is important for controlling the microstructure of the heat welding affected portion to a Martin body structure having a predetermined volume ratio. In order to play the above role, the content must be above 1.5%. On the other hand, even if the content exceeds 2.5%, not only will the effect be saturated, but the content will be excessive, so that the toughness will be lowered, and the detergency of the manufacturing step will be lowered, and the surface property will be adversely affected. Alloy cost. Therefore, the content of Μη is set in the range of 1.5 to 2.5%. It is preferably in the range of 18 to 25%. The best range is 1.85~2.0%. • P : 0.0 4 % or less P is preferably a small amount from the viewpoint of hot workability, and the upper limit 値 allowed for the content is 0.04%. And preferably 0.03 5 % or less. • S : 0 · 0 2 % or less S is preferably a small amount from the viewpoint of hot workability and corrosion resistance, and the upper limit 値 allowed for the content is 0.02%. It is preferably 0.005% or less. • A1: 0.05 to 1 5% A1 is generally used for deoxidation. However, in the present invention, it has been found to have an effective manufacturability, and in particular, it is possible to suppress the occurrence of cracks in the billet stage, and an appropriate amount can exhibit this function. In order to suppress the occurrence of cracks in the billet, in addition to the A1 content, it is necessary to further reduce the FFV 进一步 as described later in the reduction of V, Ca, and Ο. The mechanism for improving the cracking of the billet for the A1 content does not necessarily exist, but it can be estimated that the phase fraction is appropriate and the inclusion morphology is suppressed. In order to obtain the above effects, it is necessary that A1 contains 0.05% or more. On the other hand, when the content exceeds 0.15%, large-sized A1-based inclusions are formed to cause surface defects. For this reason, the content of A1 is set to be in the range of 0.05 to 0.15%. It is preferably in the range of 0.080 to 0.15%. The range is preferably 0.085 to 0.120%. -11 - 201207128 • Cr : 10~13 %

Cr is an element which forms a passivation layer film, and is essential for ensuring corrosion resistance, in particular, corrosion resistance of a heat-affected portion, and it is necessary to contain 10% or more in order to obtain the effect. On the other hand, when Cr is contained in an amount of more than 13%, not only does the cost increase, but it is difficult to ensure the high temperature of the welded portion and the iron phase of the Worstian iron is sufficient. Organization becomes difficult. As a result, the corrosion resistance against intergranular boundary in the heat affected portion of the weld is lowered. Therefore, the Cr content is set to be in the range of 10 to 13%. And preferably from 10.5 to 12.5%. • Ni : 0.5-1.0%

Ni is contained in an amount of 0.5% or more for the purpose of ensuring strength and toughness. On the other hand, Ni is an expensive element, and from the economic point of view, the upper limit is 1.%. Further, Ni is a Worstian iron stabilizing element having a high temperature similar to that of Μη, and is extremely useful for controlling the microstructure of the welded thermal shadow portion to a granulated iron structure having a desired volume ratio, but the present invention can be used by Μη The addition is sufficient to obtain the effect, so the content of Ni is suitably in the range of 0.5 to 1.0%. It is preferably in the range of 0.60 to 1.0%. The range of 〇.60~0.90% is the best. .Ti : 4x (C + N) or more and 0.3% or less

Ti is an important element for obtaining excellent corrosion resistance of the welded portion in the present invention, and is particularly required for improving the grain boundary corrosion resistance of the welded heat affected portion. Ti is a method in which c and N in steel are precipitated and fixed as a carbide, a nitride or a carbonitride of Ti (hereinafter, collectively referred to as three kinds of carbides, nitrides, and carbonitrides, and labeled as carbonitrides). The effect of the formation of Cr carbonitrides and the like. In the present invention, the welding heat-affected zone of the steel sheet has a structure composed of the ferrite iron and the granulated iron. However, in the point of corrosion resistance, there is a ferrite phase portion which precipitates with carbonitrides or the like during cooling. The problem of reduced corrosion resistance. In the steel sheet according to the present invention, the problem of the reduction of the intergranular corrosion resistance of the portion where the Cr deficiency, particularly the ferrite-grained iron phase, is generated in the vicinity of the grain boundary due to precipitation of Cr carbonitride or the like in the welding-affected portion at the time of welding can be borrowed. It contains Ti to get solved. In order to exhibit the above effects, the content of Ti must be 4x (C + N) or more (however, C and N indicate the content (% by mass)). On the other hand, when it exceeds a large amount of more than 0.3%, not only the effect is saturated, but also a large amount of Ti carbonitrides are precipitated in the steel, resulting in deterioration of toughness. Therefore, the content of Ti is set to be 4x (C + N) or more and 0.3% or less. It is preferably in the range of 0.180 to 0.23%, and C and N can be lowered to effectively make the content of cerium conform to 4x(C+N) or more. The present invention is important in terms of productivity (yield) or manufacturability, in particular, generation of cracks or surface defects caused by cracks or inclusions in the billet stage, and the reduction of V, Ca, and yttrium is important. • V: 0.05% or less V is a large amount of impurities such as Cr raw materials. When it is unexpectedly contained, it is necessary to strictly suppress the occurrence of cracks in the billet stage. From the above point of view, the content of V must be 0.05% or less. And -13 - 201207128 is in the range of 〇. 〇3 % or less, and the range is less than 0.0 3 %. When the content is 0.01% or less, it is possible to obtain a larger crack suppression, but it is necessary to select raw materials, etc., which is disadvantageous. Economic. • Ca: 0.0030% or less

Ca is an inclusion that forms a low melting point, especially causing surface defects in inclusions. Therefore, it is necessary to strictly limit the present invention, and the upper limit is made 0.0030%. The Ca content is preferably 0.0010% lower than 0.0002%, but it is necessary to carry out the selection, etc., which is not economical. .0: 0.0080% or less 〇 In order to suppress the formation of oxide-based inclusions, the content must be high, and the content must be low, and the upper limit is made 0.0080%. And preferably less than %. Further, the present invention can set the F 値 and FFV 以下 shown below to be within the range, and the corrosion resistance and productivity can be greatly improved. • F 値$ 1 1 F 値 is expressed as Cr+2xSi + 4xTi-2xNi-Mn-30x(C + N) (the symbol of each element is the content (% by mass) of these elements), and the welding heat affected part during welding The micro-structure (microstructure number 'in more detail is the parameter for estimating the volume ratio of the granulated iron structure (the residual rate of the fertilizer). For example, the weld heat shadow is exposed to the highest temperature. The effect, the better the content of the cause , the material picking property 0.0060 is appropriate, however, is the presumed) part of the ginseng iron group-14 - 201207128 is to make a part of it deteriorate into austenite (or further deterioration to (5 fat iron) (delta ferrite )), the phase deteriorates into the granulated iron during the cooling process. The proportion is stabilized by ferrite-forming elements (ferrite formation elements) and Worstian iron stabilizing elements (wo The influence of the quantitative balance of the austenite formation elements. The elements (Cr, Si, Ti) whose coefficients in the above formula are positive are the ferrite iron stabilizing elements and the elements with negative coefficients. (Ni, Mn, C, N) is Voss Iron stabilizing element. That is, the larger the F値, the more likely the ferrite iron structure remains (the volume ratio of the ferrite iron structure is large, that is, the volume fraction of the iron field in the field is small), and the smaller the ferrite iron structure, the more likely it remains. (The volume fraction of the ferrite-iron structure is small, that is, the volume fraction of the granulated iron structure is large.) In Patent Document 5, the relationship between the volume fraction of the 値田散铁 structure of the F値 and the welded heat-affected zone is investigated, and further, sulfuric acid is used. In the copper sulfate corrosion test, the corrosion resistance in the vicinity of the heat-affected zone is evaluated, and the composition is optimized. However, in the same manner as in the above-mentioned Patent Document 5, in order to obtain the improvement of the corrosion resistance of the welded heat-affected zone, the above F is provided.値 is 11 or less (Mita's loose iron volume ratio: 40% or more), and F 値: 10.5 or less (Mita's loose iron volume ratio of 60% or more) is preferable, and is preferably 10 or less. In addition, the resistance from the welded portion The lower limit of the opacity point F値 is preferably 5.0 or more, and the better range is 6.0 or more. • FFV 値$ 9.0

FFV 値 is Cr + 3 X Si + 1 6 X Ti + Mo + 2 X Al-2 X Mn-4 X -15- 201207128 (Ni + Cu) -40x (C + N) + 2 0xV (however, each The element symbol indicates the content (% by mass) of the elements, and the present invention is re-exported as an indicator of display manufacturability. The FFV値 is considered for phase balance in hot rolling, and the composition adjustment as described above, in particular, in addition to the limitation of the A1 content or the upper limit of V, Ca, and 0, the enthalpy is made small, which is obvious. Reduce the occurrence of surface defects caused by cracks and inclusions in the billet stage. The optimization of the new parameters for the amount of A1 that has not been considered is considered in consideration of setting F値, whereby the yield reduction caused by the successful suppression of the generation of surface defects is a major feature of the present invention. Although the most suitable manufacturing improvement mechanism of the FFV is not explicitly present, if the FFV 値 is 9.0 or less, the manufacturability can be remarkably improved, and the FFV 设定 is set to 9.0 or less. And 8.5 or less is preferred. Further, setting a small FFV 値 can effectively reduce the amount of Cr or increase the amount of C and N, but there is a concern that the corrosion resistance is lowered. Therefore, the lower limit of FFV 値 is preferably 5.0 or more. And the better range is above 6.0. The steel sheet of the present invention used in the state of the hot rolled sheet or the hot rolled annealed sheet is important in controlling the cracks and inclusions at the blank stage while reducing surface defects. The generation of surface defects and the fact that the cracks and the casts are greatly reduced in yield are not only poor in appearance, but also a starting point for rust generation, and therefore, it is a part that must be excluded as the product is shipped. In addition, although Mo, V, and Cu are contained in the above-mentioned formula of FFV, but the steel does not contain such a case, when it is not included, it is calculated by the component which is not contained in these 〇%. FFV値. Fig. 1 shows the relationship between the FFV 値 and the surface defect generation rate. The generation rate of the known defect is set to an appropriate range of 9.0 or less from the length -16 to 201207128 degree of the defect-generating portion with respect to the entire length of the coil, whereby the occurrence of surface defects can be remarkably suppressed. In the present invention, in addition to the above components, Cu may be contained in the following range as needed. • Cu : 1.0 or less

Cu is an element that enhances corrosion resistance, especially an element that reduces crevice corrosion. Therefore, it can be added to the occasion where the bureau is required to resist starvation. However, when the content exceeds 1.0%, in addition to lowering the hot workability, the phase equilibrium at a high temperature is destroyed, and it is difficult to obtain a predetermined structure in the welded heat affected portion. Therefore, in the case of containing Cu, the upper limit is made 1.0%. In order to fully exert the effect of improving the corrosion resistance, it is effective to have a content of 0.3% or more. The preferred range is from 0.3 to 0.5%. • Μ 〇 : 1 · 0 % or less

Mo is an element for improving corrosion resistance, and can be especially added to a place where high corrosion resistance is required. However, when the content exceeds 1.0%, in addition to lowering the workability of cold rolling, powdery spots of hot rolling are caused, and the surface quality is extremely lowered. Therefore, when Mo is contained, the upper limit is made 1.0%. When the corrosion resistance is sufficiently exhibited, the content is preferably 0.03% or more. The preferred range is from 0.1 to 1.0%. In the present invention, in addition to improving the corrosion resistance with respect to Cu and Mo at a content of 1.0% or less, the ductility is improved by a B content of 0.005% or less, and other elements may be contained according to conventional knowledge. , but • 17- 201207128 It is also important to consider the phase equilibrium at high temperatures. Further, Nb is a strong stability element, and the combination with C or N causes a large phase balance damage, so it is not added in the present invention. Further, the remainder other than the elements specified above is Fe and unavoidable impurities. In the steel sheet according to the present invention, the corrosion resistance of the welded heat-affected zone is improved. When the above F値 is 11 or less, the volume ratio of the granulated iron in the welded heat-affected zone can be 40% or more. It is preferable to set the F 値 to be 10.5 or less, and the volume ratio of the granulated iron in the heat affected zone can be made 60% or more. It is more preferable to set F 値 to 10 or less, and at this time, the volume ratio of the granulated iron in the field is 80% or more. Further, in the steel sheet according to the present invention, the parent member has a volume ratio of more than 50%, which is a ferrite iron structure. The structure of the residual portion, particularly in the hot rolled state, exists in the field of the granulated iron phase and the residual r phase, and a part of the structure containing carbonitride or the like. In particular, the structure of the hot-rolled annealed sheet after the hot-rolled sheet annealing is applied to the appropriate structural components as described later under appropriate annealing conditions is a ferrite-grained iron phase structure having a bulk porosity of approximately 100%, and has excellent workability. Next, a method of manufacturing a stainless steel sheet according to the present invention will be described below. The method for producing the stainless steel sheet according to the present invention may be carried out according to a usual method, and is not particularly limited. However, the method of efficiently producing the steel obtained by melting the above-mentioned component composition can be formed into a billet by continuous casting or the like. The hot rolled coil is formed, and if necessary, it is subjected to descaling (shot blasting, pickling, etc.), and is recommended as a method for the stainless steel sheet according to the present invention. -18- 201207128 The following is a detailed description. First, the steel which is adjusted to the composition of the present invention is melted by a conventional melting furnace such as a steel converter or an electric furnace, and then subjected to a vacuum degassing method (RH method). A conventional scouring method such as the VOD (Vacuum Oxygen Decarburization) method is scoured, and then a steel material (steel material) is formed by a continuous casting method or a block-blocking method. The casting method is preferably continuous casting from the viewpoint of productivity and quality. Further, the thickness of the billet is preferably 100 mm or more in order to secure a lower pressing ratio of hot rough rolling to be described later. Further, the range is more than 200 mm. Next, the steel material is heated to a temperature of 1,100 to 1,300 ° C, and then hot rolled to form a hot rolled steel sheet. The billet heating temperature is such that the surface roughness resistance of the hot rolled sheet and the anti-ridging property or ridging property are higher, but once it exceeds 1300 ° C It will obviously cause the billet to sag, or coarsen the crystal grains to reduce the toughness of the hot rolled sheet. On the other hand, a heating temperature of less than 1 l ° C increases the load of hot rolling, and the recrystallization in hot rolling is insufficient, in addition to the fact that the hot rolled powder spot becomes conspicuous. Still, the hot plate is lowered. The step of hot rolling is preferably carried out by rolling at least 30 times or more in a temperature range of more than 1 000 °C. By this, a strong press rolling is performed to make the crystal structure of the steel sheet finer and to improve its toughness. Hot rough -19- 201207128 After rolling, hot working rolling is carried out according to a conventional method (normal hot rolling conditions). A hot-rolled sheet having a thickness of about 2.0 to 8.0 mm produced by hot rolling can be used as a structural material in this state or after pickling without being annealed. It is also possible to subject the hot rolled sheet to annealed at a temperature of 600 to 1 000 °C and then pickled. When the annealing temperature of the hot-rolled sheet is less than 600 ° C, there may be a case where the fertile iron phase and the remaining 7 phases remain in the hot-rolled state, and the volume fraction of the ferrite iron structure is less than 50%, which is not obtained. Fully processable. On the other hand, when the thickness exceeds 1 OOO, the grain coarsening becomes remarkable, and the toughness is lowered. The annealing of the hot rolled sheet is preferably carried out at a predetermined temperature of 600 to 1000 ° C for 1 hour or more by so-called box annealing. Further, when the annealing temperature is too high, there is a case where the temperature at which the r-phase transformation occurs is not preferable. For this reason, it is necessary to adjust the composition to the appropriate range and select the appropriate temperature range corresponding to its composition. In the composition range of the steel of the present invention, it is mainly set at an annealing temperature of 600 to 900 ° C, so that a volume ratio of about 100% becomes a ferrite iron phase, and this temperature range is preferable. The stainless steel plate according to the present invention is welded by TIG welding, arc welding, seam welding, spot welding, etc., and laser welding. All the usual welding methods can be used. [Examples] -20-201207128 stainless steel having the composition shown in Table 1 was formed into a billet of 200 mm by a converter-VOD-continuous casting method. After the billet was heated to a temperature of 8 〇 «c, a coil-shaped hot-rolled sheet having a thickness of 5.0 mm was formed by hot rolling. The hot rolling completion temperature was 900 °C, and the coiling temperature after hot rolling was 700 t. The obtained hot-rolled steel sheet is annealed at 690 ° C for 1 〇 hour, and then subjected to sand blasting and pickling to remove scale. A flat plate sample is cut out from the steel sheet removed from the scale. , assembling a τ-type test body formed by a lower plate and an upright plate, performing both side single pass fillet welding (gas metal arc welding, shielding gas) : 98 Capacity % Ar-2 Capacity % 〇 2, Flow: 20 liters / minute) " Three fillet test pieces were produced. The welding rod is made of MGS-309LS manufactured by Kobe Steel Co., Ltd., a limited company, and the heat supply is in the range of 0.4 to 0.8 kJ/mm. From the corner welded portion of the fillet-welded test piece, a corrosion test piece was taken for a sulfuric acid-copper sulfate corrosion test (Modified Strauss test based on ASTM A262 practice E and ASTM A763 practice Z, and the test liquid was Cu/6% CuSO4). /0.5% H2S04, the end-honored test piece was immersed in the boiling liquid for 20 hours), and the corrosion condition in the vicinity of the heat affected portion of the weld was observed. Fig. 2 is an optical micrograph showing an observation example of a cross section of a test piece after a sulfuric acid-copper sulfate corrosion test. As shown in the photograph, it is confirmed that the grain boundary corrosion is confirmed by the welding heat-affected zone, or C is confirmed to have deep-hole corrosion, and B is confirmed when some micro-corrosion is confirmed, and corrosion is not confirmed by observation by the optical microscope. The occasion is evaluated for A. Further, the surface state after pickling of the hot rolled annealed sheet was observed across the full length -21 - 201207128. The ratio of the length of the surface defect caused by the observation of the foreign matter to the full length was evaluated as a ratio of the defect generation to 3 % or less, and more than 3% to b and more than 30% to c. As a result, in the 10-13 and 15 of the present invention example within the scope of the present invention, the welded portion has good corrosion resistance and a good surface shape. On the other hand, in the comparative example 14 in which F値 deviated from the scope of the present invention, the amount of granulated iron generated in the welded thermal shadow portion was small, and corrosion was remarkably inferior. Further, Si is higher than the range of the present invention, and No. 6 and FFV of the comparative example having a low range of A1 deviate from No. 7, 8, 9, and 14 of the comparative example of the present invention, and the billet is observed at the surface of the hot-rolled annealing. The crack of the material and the casting of the inclusions. The steel of the present invention causes the casting of the hot rolled sheet or the hot rolled annealed sheet to cause a large decrease in the yield. If the cast part is not good, it will become the starting point of rust, so it is a part of the product that must be excluded. Crack or pinch is an indicator, up to 30%: shown in Tables No. 1 to 5, and also excellent in No. 9 and this anti-grain boundary is more useful than the scope of the present invention, so only the appearance is not When the goods are available -22- 201207128

Bg* 辑; 饀慝 饀慝 饀慝 灵 m m 灵 m a BS» m 镒 Jj UA 翳镒 UA 翳镒 s: m sg 7M 溆 1; 鹬 馏 镒 镒 . . . . . . . . . . . . . Cd σ> CO 00 SI SI CO csi T- in σ> 00 inch ιο σ> §1 GO Crane U. CM 00 OJ σ> in 00 σ> 00 5 CO od 5 5 CSI csi GO CM d ·»— 5 C0 Od _ _ κ 5 E S S S E E E E E E E E E E E E E E E E E E E 〇 〇 〇 〇 〇 〇 〇 〇 〇 〇 E E E E E E E E E E E E E E E E E E E E Sp ο S ο ο to CO ood ΙΟ S ρ ο S ο CSJ CO oo in o to sp K oosoo inch ο d to g ο ο σ> g ο ο CO ιη ο ο ο ο 2: soo οι ο ο 〇 σ> O o ιη χο ο ο ιη 5 Ο different ooo 5 oo ▼*· oosoo V— od τ— ο ο GO 00 00 00 δ Ο C0 σ> ο ο S ο ο > T-· oo ο ο od ο ο Ο — — — — — — 兮 5 5 5 5 5 5 5 5 5 CM CM CM 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 Art 5 ιη S ο s Csj CO ό CNI r* CO csi τ— ο csi 〇· τ— τTM CSI T·· CNI T~ σ> in ▼— o CO T— Ο τTM Ο C0 τ- ιη γ» - l〇CO 〇ιο 00 ο ο ο ο GO S ο V— O) oo σ> 8 ο CO GO to 〇> d LO Ο) ο ο G0 ο S ο 卜 Ο Ο in o' < S 5 S 5 σ> Τ Ο & ο ο S 5 CO oo in od ο ο s ο ο CO d 5 d S d CSI CM 5 S CSi ο Ο ▼ — 5 CO sod ο ο ο ο ο S ο ο CO ο ο o o C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C ο sod «Ι Ο 〇 · S ο ο CM Ο Ο S ρ S ρ Q- sd σ> S ο ο ο S S ο ο S ο oso LO CM oo ο S § σ > CM ρ ο CO CM oo ο d τ —C0 ο ο S ο ο ο ο S ο C Έ GO GO C0 ΙΟ τ— ο 〇> ιη σ> o ▼*· o ΙΟ 00 τ— 9 〇> τ~ GO ιη σ>σ> 00 CSI τ — ιη C0 W inch CM 〇 ο 00 CM ο CSJ ο ο ΙΛ ooo ο ο S ο σ > CM 〇Ο ο σ> ?r — Ο CM C>4 Ο 00 CO ο ιη CSI ο 〇Csj eg O 〇· ΙΟ CSJ ο ο ιη τ·· ο ο S ο ο 00 ο ο CO oo CM so S ο ο ο s o o σ > ΊΓ- square · ιο CM Ο Ο CN4 S Ο ιη CNJ ο ο C0 S ο 1 οα CO ιη CO 00 σ > o CSJ C0 τ ™ ιη -23- s 8 201207128 [Table 2] TABLE 2

No. Sulfuric acid-copper sulfate test results Surface quality 1 A a Invention steel 2 A a Invention steel 3 A a Invention steel 4 A a Invention steel 5 A a Invention steel 6 A b Comparative steel 7 A b Comparative steel 8 B b Comparative steel 9 C c Comparative steel 10 A a Invention steel 11 A a Invention steel 12 A a Invention steel 13 A a Invention steel 14 C b Comparative steel 15 A a Invention steel A: No corrosion B: Some micro-corrosion C: Grain boundary corrosion or deep Pore corrosion a: defect generation rate 3% or less b: defect generation rate 3% more than 30% or less c: defect generation rate 30% exceeds [schematic description] Chart. Fig. 2 is a photomicrograph showing an observation example in which the deep-hole corrosion was confirmed in the welding heat-affected zone of the test piece profile after the sulfuric acid-copper sulfate corrosion test. -twenty four-

Claims (1)

201207128 VII. Patent application scope: 1. - Stainless steel plate for structural use, containing mass %: C: 0.01-0.03%, N: 0.01-0.03%, Si: 0.10~0.40%, Mn: 1. 5~2.5 % Ρ : 0.04% or less, S: 0.02% or less, Α1: 0·05 to 0.15 %, Cr: 10-13%, Ni: 0.5 to 1 .〇%, Ti: 4x(C + N) (however, c N is not less than the content (% by mass) of the above, and 0 _ 3 % or less, and is limited to: V: 0.05% or less, Ca: 0.0030% or less, 0: 0.0080% or less, and the following formula F値 and FFV値 conform to F値S 11 and FFVS9.0, and the residual part is Fe and inevitable impurities. Stainless steel plate for construction, F 値=C r + 2XS i+4XTi-2XNi -Μη - 3 Ο X (C + N) ??¥値=(^ + 3 parent 3 1 + 16 parent 1'1+1^[〇+ 2 parent eight 1-2\1^11-4 parent (Ni+Cu) -40X ( C + N) +20XV However, in each of the formulas, 'the symbol of each element is the content of the elements (-25-201207128% by mass). 2. The stainless steel plate for construction described in the first paragraph of the patent application 'where' And contains 0.00% by mass of Cu: 1.0% or less. The stainless steel plate for construction described in the first or second aspect of the present invention includes a mass % of Mo: 1.0% or less. 制造4. A method for producing a stainless steel plate for structural use, containing mass % C : 0.01 〜 0.03%, N: 0.01 to 0.03%, Si: 0·1 〇~0.40%, Μ η: 1. 5 to 2.5%, Ρ: 0 · 〇4% or less, S: 0.0 2% or less, Α1: 0.05~ 0.1 5%, Cr: 10-13%, Ni: 0.5 to 1.0%, Ti: 4x (C + N) (however, C and N are the contents (% by mass)) or more, and 〇. 3 % or less. , and the restrictions are: V : 0 · 〇 5 % or less, Ca: 0.0030% or less, 0: 0.0080% or less, and F 値 and FFV 表示 expressed by the following formulas are in accordance with F値$ -26- 201207128 11, FFVS9. 0. After heating the slab having a composition of Fe and unavoidable impurities to a temperature of 11 〇〇 to 1 300 ° C, a pressure reduction rate of at least one time is performed in a temperature region exceeding 1000 ° C. More than 30% hot rolling of hot rough rolling, and after the above hot rolling, the hot rolled sheet is not annealed but is carried out at a temperature of 600 to 1 000 °C. Residual part of the manufacturing method of stainless steel plate for pickling structure after fire, F 値=C r + 2XSi+4XTi-2XNi -Μη-3 Ο X (C+N) FFV値= Cr + 3XS i + 1 6XT i + Mo + 2XA1 - 2XMn - 4X (Ni + Cu) - 40X (C + N) + 20XV However, in the formulas, the symbol of each element is the content (% by mass) of the elements. 5. The method for producing a stainless steel sheet for a structure according to the fourth aspect of the invention of the invention of the fourth aspect of the present invention, wherein the content of Cu: 1.0% or less by mass% is contained. (6) The method for producing a stainless steel sheet for structural use according to the fourth or fifth aspect of the invention, wherein the composition contains Mo% by mass or less of 1.0% or less. -27-