JP4624808B2 - Ferritic stainless steel sheet with excellent workability and method for producing the same - Google Patents

Description

  The present invention relates to a ferritic stainless steel sheet as a material for a molded product requiring particularly excellent formability and a method for producing the same.

  Ferritic stainless steel sheets are used in a wide range of fields such as home appliances, kitchen equipment, electronic equipment, transport machinery, and structural members. However, since the formability is inferior to that of an austenitic stainless steel sheet, there are cases where the use is limited. For example, in recent years, the application of stainless steel plates is being studied as a material used for fuel tanks and pipes of automobiles and motorcycles. Corrosion resistance in a fuel environment and workability for forming into a pipe or the like are required. These internal environments can be said to be extremely harsh because organic acids generated by the deterioration of gasoline promote corrosion of steel materials. For this reason, surface-treated steel sheets have been used as steel materials for dealing with corrosive environments on the inner and outer surfaces. However, there have been problems such as long-term corrosion resistance, weldability, and environmental problems due to elution of the plating layer. Although attempts have been made to use resins, there are problems from the viewpoint of fuel permeability and recycling. Furthermore, in recent years, the warranty period of fuel parts is being extended from 10 years to 15 years from the viewpoint of environmental protection, and replacement of the above-mentioned surface-treated steel sheets and resins is required.

  In this way, from the viewpoint of corrosion resistance, a stainless steel plate with excellent corrosion resistance is suitable as a material. In addition to being high, there was a problem that the reliability against stress corrosion cracking in the salt damage environment of the outer surface was low. On the other hand, the ferritic stainless steel sheet has the advantage that stress corrosion cracking, which is a drawback of the austenitic stainless steel sheet, does not occur, but it is difficult to ensure formability to be processed into a fuel part having a complicated shape.

  Several ideas have been made to solve the problems related to formability of ferritic stainless steel sheets. For example, regarding fuel parts that are severely processed, Patent Document 1 includes a method for defining the line pressure (value obtained by dividing the rolling load by the sheet width) in the finish rolling process in the hot rolling process, and hot rolling sheet annealing conditions. A method of defining is disclosed. Patent Document 2 discloses a method for prescribing an X-ray integral intensity ratio, a temperature and a rolling reduction in hot rolling rough rolling, and performing intermediate annealing in addition to hot rolling sheet annealing. Patent Documents 3 to 6 disclose what defines the r value. These improve the average r value. However, in actual fuel parts, it is not sufficient to improve the average r value. The reason for this is that when hot-rolled sheet annealing is performed, the crystal grain size becomes coarse, and the effect of refining the structure before cold rolling cannot be obtained. In particular, in the case of a fuel pipe, the pipe is formed after pipe forming. However, if the r value in the rolling direction and the 45 ° direction or 90 ° direction is low, the pipe may break in these directions. It was necessary to particularly improve the r value in the direction of ° or 90 ° and reduce the in-plane anisotropy of the r value. Furthermore, the conventional manufacturing method has a problem in that efficient steel sheet manufacturing cannot be performed.

JP 2002-363712 A JP 2002-285300 A JP 2002-363711 A JP 2002-97552 A JP 2002-60973 A JP 2002-60972 A

  An object of the present invention is to solve the problems of the known techniques and efficiently produce a ferritic stainless steel sheet having excellent workability.

  In order to solve the above-mentioned problems, the present inventors conducted detailed studies on the formability of ferritic stainless steel sheets from the viewpoints of components, structure in the manufacturing process, and crystal orientation. As a result, the processing characteristics of ferritic stainless steel sheets required for press formability on fuel parts are complicated by setting the r value in the 45 ° and 90 ° directions and the total elongation to 1.5 and 30% or more, respectively. It was found that even parts with various shapes can be processed.

The gist of the present invention for solving the above problems is as follows.
(1) In mass%, Cr: 14 to 25%, C: 0.001 to 0.005%, Si: 0.01 to 0.20%, Mn: 0.01 to 0.20%, P: 0.01-0.03%, S: 0.0005-0.0100%, N: 0.001-0.020%, Ti: 0.05-0.20%, Mo: 0.5-2. 0%, B: 0.0002 to 0.0030%, the balance is made of Fe and inevitable impurities, r ₄₅ and r ₉₀ are 1.5 or more, EL ₄₅ and EL ₉₀ are 30% or more, {111} <112> Ferritic stainless steel sheet for fuel parts excellent in workability, characterized by having an orientation strength of 10 or more and {411} <148> orientation strength of 3 or more .
Here, r ₄₅ is the r value in the rolling direction and 45 ° direction, r ₉₀ is the r value in the direction perpendicular to the rolling direction, EL ₄₅ is the total elongation in the rolling direction and 45 ° direction, and EL ₉₀ is in the direction perpendicular to the rolling direction. Total growth .
( 2 ) Further, in mass%, Ni: 0.2 to 1.0%, Nb: 0.05 to 0.60%, Cu: 0.2 to 3.0%, V: 0.05 to 1. A fuel excellent in processability according to (1 ) , characterized by containing one or more of 0%, Mg: 0.0002 to 0.0030%, Al: 0.005 to 0.100% Ferritic stainless steel sheet for parts .
( 3 ) The process according to (1) or (2) , wherein the cold rolled material is cold-rolled and subsequently annealed with a recrystallized grain size of 80 μm or less and a recrystallization rate of 90% or less. Of ferritic stainless steel sheet for fuel parts with excellent properties.
( 4 ) When stainless steel slab is hot-rolled, continuous rolling is performed at a slab heating temperature of 1100 to 1250 ° C. and a ratio of the total rolling reduction of rough rolling to the total rolling reduction of finish rolling of 0.8 to 1.0. Is performed at a finish rolling finish temperature of 700 to 900 ° C., wound at 650 to 850 ° C., and then subjected to cold rolling and annealing by omitting hot rolling plate annealing ( 3 ) Of excellent ferritic stainless steel sheet for fuel parts .

  According to the present invention, the production of a ferritic stainless steel sheet for fuel parts having excellent formability can be efficiently provided without requiring new equipment and without performing hot-rolled sheet annealing.

  The reason for limitation of the present invention will be described below. Workability and corrosion resistance are required for the steel of the fuel component material, which is the main use of the product of the present invention. As an index of workability, there are an r value that is an index of deep drawability and an elongation that is an index of stretchability. In fuel parts, when both are high, the size that can be formed increases, but as a result of examining the processing state of various parts in detail, the r values in the 45 ° direction and 90 ° direction with respect to the rolling direction in the steel plate that is the material. It was proved that high total elongation was effective. Usually, only the r value in the rolling direction (0 ° direction) and the total elongation, or the average values in the 0 °, 45 °, and 90 ° directions are used as indicators of material formability. In some cases, the pipe could not be molded. The fuel pipe is made of a steel plate material (formed into a pipe shape and then welded into a pipe), and the end of the pipe is expanded (by pushing a mold larger than the pipe diameter from the end of the pipe, However, even if the average r value and the total elongation of the material are high, cracks may occur in the 45 ° direction and the 90 ° direction during tube expansion processing. This is because large tensile deformation acts in the circumferential direction of the pipe (90 ° direction of the material) during pipe expansion processing, and the tensile deformation in the circumferential direction and compression deformation that acts in the axial direction of the pipe (0 ° direction of the material). It can be considered that a large tensile deformation acting in the 45 ° direction of the material acts as a composite force. As a result of processing a material having various material characteristics, if the r value and elongation in the 45 ° direction and 90 ° direction are 1.5 and 30% or more, respectively, with respect to the rolling direction of the material, cracks will not occur during tube expansion. There was found.

In the present invention, it has been found that the texture of the product plate greatly affects the above characteristics. In general, it is effective to develop a crystal orientation in which the {111} plane is parallel to the plate surface in order to improve the r value, but in order to improve the r value and elongation in the 45 ° direction and 90 ° direction. It was found that the development of {111} plane orientation alone is not sufficient. This is because when only the {111} plane orientation is developed in relation to the slip system that occurs when a metal structure having a body-centered cubic structure such as ferritic stainless steel is deformed, the r value and elongation in the 45 ° direction are particularly significant. Will fall. FIG. 1 shows ferritic stainless steel sheets (17% Cr-1.2% Mo-0.15% Ti-0.003% C-0.01% N-0. 0005% B-0.0010% S-0.1% Si-0.1% Mn steel, plate thickness 0.6 mm). Here, for the texture, an X-ray diffractometer (manufactured by Rigaku Denki Kogyo Co., Ltd.) is used, and Mo-Kα rays are used to reveal the central region of the plate thickness (the central region is a combination of mechanical polishing and electrolytic polishing) ) (200), (110), and (211) positive electrode dot diagrams were obtained, and a three-dimensional crystal orientation density function was obtained from these using the spherical harmonic function method. Evaluation of the r value is obtained by collecting JIS13B tensile test pieces from cold-rolled annealed plates and applying 15% strain in the rolling direction, the rolling direction and 45 ° direction, and the rolling direction and 90 ° direction (1). It calculated using.
r = ln (W ₀ / W) / ln (t ₀ / t) (1)

Here, W ₀ is the sheet width before tension, W is the sheet width after tension, t ₀ is the sheet thickness before tension, t is the sheet thickness after tension, r ₀ is the r value in the rolling direction, and r _45. Is the r value in the rolling direction and the 45 ° direction, and r ₉₀ is the r value in the direction perpendicular to the rolling direction. For evaluation of total elongation, JIS No. 13 B tensile test specimens were collected from cold-rolled annealed plates and subjected to tensile tests in the rolling direction, rolling direction and 45 ° direction, and rolling direction and 90 ° direction, and the elongation at break was measured. Here, EL ₀ is the total elongation in the rolling direction, EL ₄₅ is the total elongation in the 45 ° direction with respect to the rolling direction, and EL ₉₀ is the total elongation in the direction perpendicular to the rolling direction. FIG. 1 is a cross section (φ ₂ = 45 ° cross section) in which the strength of the main crystal orientation of a ferritic stainless steel sheet (strength ratio with a random sample) can be seen in the notation of a three-dimensional texture called the Bunge method. . Accordingly, when the {111} <112> azimuth strength is 10 or more and the {411} <148> azimuth strength is 3 or more, the r value and the elongation in the 45 ° direction and the 90 ° direction are 1.5 and 30%, respectively. It turns out that it is above. Even if the {111} <112> azimuth strength is 10 or more, when the {411} <148> azimuth strength is less than 3, particularly, the r value and the elongation in the 45 ° direction are less than 1.5 and 30%, respectively. The {411} <148> orientation is considered to be the recrystallization orientation of some rolling orientations (for example, {100} <011>). By appropriately presenting this orientation, the r value in the 45 ° direction, in particular, It is considered that a material with improved elongation and small in-plane anisotropy can be obtained.

  Next, the component range of steel will be described.

  Since C deteriorates moldability and corrosion resistance, the lower the content, the better. Therefore, the upper limit was made 0.005%. However, excessive reduction leads to an increase in refining costs, so the lower limit was made 0.001%. Furthermore, if considering the manufacturing cost and corrosion resistance, 0.002 to 0.003% is desirable.

  Si may be added as a deoxidizing element, and also improves oxidation resistance. However, since it is a solid solution strengthening element, the lower the content, the better, so the upper limit is 0.20%. did. On the other hand, from the viewpoint of refining costs, the lower limit was made 0.01%. Furthermore, considering the material, the upper limit is preferably 0.10%.

  Since Mn is a solid solution strengthening element like Si, the lower the content, the better. Therefore, the upper limit was made 0.20%. On the other hand, excessive reduction leads to an increase in refining costs, so the lower limit was made 0.01%. Furthermore, considering the material, the upper limit is preferably 0.10%.

  Since P is a solid solution strengthening element like Mn and Si, the lower the content, the better. Therefore, the upper limit was made 0.03%. However, excessive reduction leads to an increase in raw material cost, so the lower limit was made 0.01%. Furthermore, if considering the manufacturing cost and material, 0.013 to 0.020% is desirable.

Since S is an element that degrades the corrosion resistance, the upper limit was made 0.0100%. On the other hand, in the case of Ti-containing steel, Ti ₄ C ₂ S ₂ is formed at a high temperature and contributes to the development of a texture that is superior in formability. Since this occurs from 0.0005%, the lower limit was set to 0.0005%. Furthermore, when considering refining costs and suppression of crevice corrosion when fuel parts are used, 0.0010 to 0.0060% is desirable.

  Cr is an element that improves the corrosion resistance, and if considering the environment of fuel parts, 14% or more is necessary. On the other hand, excessive addition causes hardening and deteriorates moldability, so the upper limit was made 25%. In addition, when considering the plate cost at the time of manufacturing due to the manufacturing cost and toughness deterioration, 17 to 23% is desirable.

  N, like C, deteriorates formability and corrosion resistance, so the lower the content, the better. Therefore, the upper limit was made 0.020%. However, excessive reduction leads to an increase in refining costs, so the lower limit was made 0.001%. Furthermore, if considering the manufacturing cost, workability, and corrosion resistance, 0.004 to 0.010% is desirable.

  Ti is an element that combines with C, N, and S to improve corrosion resistance, intergranular corrosion resistance, and deep drawability. Since the C and N fixing action appears from 0.05%, the lower limit was made 0.05%. Further, addition of more than 0.25% hardens with solute Ti and deteriorates weldability, so the upper limit was made 0.25%. Furthermore, considering deep drawability, production cost, surface wrinkles generated during production, etc., 0.10 to 0.20% is desirable.

  In some cases, Al is added as a deoxidizing element, and its action is manifested from 0.005%, so the lower limit was made 0.005%. Further, addition of 0.100% or more causes a decrease in elongation, deterioration of weldability and surface quality, so the upper limit was made 0.100%. Furthermore, 0.01 to 0.08% considering the refining cost is desirable.

  Mo is an element that improves corrosion resistance, and is an element that is necessary for suppressing crevice corrosion, particularly when it has a crevice structure. If this effect is less than 0.5%, corrosion will occur on the inner and outer surfaces of the fuel component, so the lower limit was made 0.5%. On the other hand, if it exceeds 2.0%, the moldability is remarkably deteriorated and the manufacturability is deteriorated, so the upper limit was made 2.0%. Furthermore, if considering the manufacturing cost, 1.0 to 1.8% is desirable.

  B is an element that improves the secondary workability of the product by segregating at the grain boundaries. In order to prevent cracking especially in winter after being processed as a fuel part, it is necessary to add 0.0002% or more. However, excessive addition causes deterioration of workability and corrosion resistance, so the upper limit was made 0.0030%. Furthermore, if considering cost and ductility reduction, 0.0003 to 0.0010% is desirable.

  Ni is added as needed to suppress crevice corrosion and promote repassivation. Since this effect appears at 0.2% or more, the lower limit was set to 0.2%. However, excessive addition hardens and deteriorates moldability, and stress corrosion cracking tends to occur, so the upper limit was made 1.0%. Furthermore, if considering material properties and raw material costs, 0.3 to 0.8% is desirable.

  Nb is added as necessary to suppress crevice corrosion and promote surface repassivation. Since this effect appears at 0.05% or more, the lower limit was made 0.05%. However, excessive addition hardens and deteriorates moldability, so the upper limit was made 0.60%. In consideration of deep drawability and raw material cost, 0.1 to 0.5% is desirable.

  Cu is added as necessary to suppress crevice corrosion and promote repassivation. Since this effect appears from 0.2% or more, the lower limit was made 0.2%. However, excessive addition hardens and deteriorates moldability, so the upper limit was made 3.0%. In consideration of manufacturability, 0.5 to 1.5% is desirable.

  V is added as necessary to suppress crevice corrosion. Since this effect appears from 0.05% or more, the lower limit was made 0.05%. However, since excessive addition hardens and deteriorates moldability, the upper limit was made 1.0%. In consideration of the raw material cost, 0.1 to 0.5% is desirable.

  Mg may be added as a deoxidizing element, and is an element that contributes to improving the formability by refining the structure of the slab or promoting the refining of the structure of the weld. Since this is expressed from 0.0002% or more, the lower limit was made 0.0002%. However, excessive addition leads to deterioration of weldability and corrosion resistance, so the upper limit was made 0.0030%. Furthermore, if considering surface defects and refining costs, 0.0003 to 0.0010% is desirable.

  Next, a manufacturing method will be described. The method for producing a steel sheet of the present invention comprises a step of repeating cold rolling and annealing after steelmaking-hot rolling-pickling. In steelmaking, a method in which the steel containing the above essential components and components added as necessary is subjected to furnace melting followed by secondary refining. The molten steel is made into a slab according to a known casting method (continuous casting). The slab is heated to a predetermined temperature and hot-rolled to a predetermined plate thickness by continuous rolling.

In the present invention, in order to improve the r value and the total elongation in the 45 ° direction and 90 ° direction with respect to the rolling direction in the product plate, it is extremely important to control the structure of the hot rolled plate. It has been found that it is better not to perform sheet annealing. The hot-rolled sheet annealing is for obtaining a sized recrystallized structure before cold rolling, but with this, the crystal grains before cold rolling cannot be made fine, whereby {111} <112> orientation does not develop sufficiently, or {411} <148> orientation does not occur appropriately, and the r value and elongation in the 45 ° direction decrease. 2 and 3 show the structure of the cold rolled material and the material of the product plate. Here, 17% Cr-1.2% Mo-0.15% Ti-0.003% C-0.01% N-0.0005% B-0.0010% S-0.1% Si-0 A 1% Mn steel was prepared by cold rolling to a thickness of 5 mm under various hot rolling and annealing conditions, and after cold rolling to a thickness of 0.8 mm, 950 ° C. × 60 sec → A. Finish annealing was performed at C. In FIG. 2, the horizontal axis is plotted as the crystal grain size (μm) of the cold-rolled material, and the vertical axis is plotted as the r value of the product plate. A straight line is displayed as a legend near the rightmost plot in the figure. The three points connected with each indicate r ₀ , r ₄₅ , and r ₉₀ , respectively, and the number with% displayed in the vicinity thereof is the recrystallization rate of the cold-rolled material. In FIG. 3, the horizontal axis is plotted as the crystal grain size (μm) of the cold-rolled material, and the vertical axis is plotted as the total elongation of the product plate, and is displayed as a legend near the rightmost plot in the figure. The three points connected by straight lines indicate EL ₀ , EL ₄₅ , and EL ₉₀ , respectively, and the number with% displayed in the vicinity thereof is the recrystallization rate of the cold-rolled material. From these figures, when cold rolling-annealing is performed using a material having a recrystallization grain size of 80 μm or less and a recrystallization rate of 90% or less, r values in 45 ° direction and 90 ° direction are shown. And the total elongation is 1.5 and 30% or more, respectively.

In order to obtain the above structure with a hot-rolled sheet, manufacturing conditions in the hot-rolling step are specified. The slab obtained by continuous casting is a hot rolled steel sheet having a predetermined thickness in the hot rolling process. Here, in order to stably obtain a steel sheet having a high r value and n value, it is necessary to perform hot rolling by the method described above. The slab heating temperature is such that if the heating temperature is too high, Ti carbon sulfide (Ti ₄ C ₂ S ₂ ) dissolves during heating, and recrystallization occurs due to an increase in solute carbon and reprecipitation during the hot rolling process. A phenomenon such as delay occurs. These phenomena suppress the development of the recrystallized texture of the product plate and deteriorate the workability. Further, the crystal grains are significantly enlarged, and coarse expanded grains are formed in the hot rolling process, so that the workability of the product plate is deteriorated. In addition, excessive temperature decrease causes surface flaws and causes corrosion resistance deterioration due to flaws from the ridges. For this reason, slab heating temperature is prescribed | regulated to 1100-1250 degreeC. Furthermore, in consideration of productivity reduction due to rolling roll seizure, the slab heating temperature is preferably 1130 to 1230 ° C.

  In the hot rolling process, the rolling process is divided into a rough rolling process and a finishing rolling process including a plurality of stands, each of which is rolled in a plurality of passes. After rough rolling, finish rolling is performed at a high speed and the coil is wound into a coil. In the present invention, in order to obtain fine recrystallized grains at the time of winding, the ratio between the rough rolling reduction ratio and the finish rolling reduction ratio and the finish rolling end temperature are defined. If the ratio between the rough rolling reduction ratio and the finish rolling reduction ratio is too high, the strain introduced in the finish rolling is reduced, and recrystallization is not promoted during winding. On the other hand, if this is too low, stretched grains remain in the structure before finish rolling, and recrystallization does not occur even in finish rolling and winding. Furthermore, the finish rolling finish temperature and the winding temperature also affect the formation of the structure. If the finishing temperature and the winding temperature are too low, a fine recrystallized structure cannot be obtained. do not do. From this, the ratio of the total rolling reduction of rough rolling and the total rolling reduction of finish rolling was set to 0.8 to 1.0. On the other hand, if the finishing temperature and the winding temperature are excessively high, coarse recrystallized grains are formed. On the other hand, if these are excessively low, recrystallization does not occur at the time of winding. The temperature is 900 ° C and the winding temperature is 650 to 850 ° C.

  About the process after a hot rolling, it pickles without carrying out a hot-rolled sheet annealing, performs cold rolling, annealing, and pickling, and uses for a cold rolling process. In the present invention, a product is obtained by performing pickling, cold rolling, annealing, and pickling without performing hot rolling sheet annealing. At this time, in the cold rolling process, it is desirable to perform tandem unidirectional rolling using a large diameter roll having a roll diameter of 400 mm or more.

  Invention steels A to E and comparative steels F to U having the composition shown in Table 1 were melted and cast into a slab, and the slab was hot-rolled to obtain a hot-rolled coil having a thickness of 5 mm. Then, it pickled without performing hot rolling sheet annealing, and used for cold rolling. For comparison, a hot-rolled sheet annealing was also included, and the product was commercialized by cold rolling and annealing.

  Table 2 shows the components, manufacturing methods, and material properties of the steel sheets produced by manufacturing various steels. For the material, the r value and the total elongation were measured by the method described above. As for the corrosion resistance, as an evaluation in a salt damage environment, a cyclic corrosion test in which a cycle of spraying → drying → immersion → drying is performed for 100 days continuously using a 5 mass% NaCl solution (50 ° C.), The corrosion depth was measured, and the case where the depth was 1/2 or less of the plate thickness was determined to be acceptable (◯), and the case where the depth was 1/2 or more was determined to be unacceptable (x). Further, as an evaluation in the fuel environment, the steel sheet was immersed in a solution containing 10% distilled water in deteriorated gasoline for 28 days, and then the corrosion state was observed. The case where corrosion did not occur in appearance and there was no significant change was judged as acceptable (◯), and the case where wrinkles occurred was regarded as unacceptable (x). As for press formability, pipes (φ25.4 mm) that have been pipe-welded to a predetermined shape are expanded (φ50.8 mm), and if there are no abnormalities such as cracks, they pass (○). When this occurred, it was regarded as a failure (x). From Table 2, it can be seen that in the example of the present invention, tube expansion processing is possible and the corrosion resistance is also excellent. In Comparative Examples No. 10 and 16, since a large amount of C and N is added, the r value and total elongation are low, the moldability is inferior, and the corrosion resistance in the fuel environment is poor. In Comparative Examples No. 14 and 25, a large amount of S or Mg is added and processing is possible, but the corrosion resistance is poor. Comparative Example 19 is inferior in moldability and salt corrosion resistance because B is added in a large amount. Moreover, since it is outside the scope of the present invention for other elements, the formability is poor. As for manufacturing conditions, Comparative Examples No. 26 and 31 to 36 subjected to hot-rolled sheet annealing have a recrystallization rate of 100% and a recrystallized grain size of more than 80 μm, which is a product plate. {411} <148> strength and {111} <112> strength are out of the range of the present invention, and the r value in the 45 ° direction is lowered. Therefore, cracks occur when the pipe is expanded. Even under conditions where hot-rolled sheet annealing is not performed, Comparative Example No. 27 whose hot-rolling conditions are outside the scope of the present invention has a coiling temperature that is too high, and the structure of the cold-rolled material is coarsened, resulting in poor formability. Moreover, since comparative example No28-30 is a slab heating temperature, ratio of the total rolling reduction ratio of rough rolling, and the total rolling reduction ratio of finish rolling, and finish rolling completion temperature are outside the scope of the present invention, the recrystallized grain size of the cold rolled material Becomes too large and is inferior in moldability.

  Note that other conditions in the manufacturing process may be appropriately selected. For example, what is necessary is just to design slab thickness, hot rolling board thickness, etc. suitably. In cold rolling, roll roughness, rolling oil, number of rolling passes, rolling speed, rolling temperature, etc. may be appropriately selected. Further, if necessary, the annealing atmosphere may be bright annealing performed in a non-oxidizing atmosphere such as hydrogen gas or nitrogen gas, or annealing in the air. Furthermore, the product plate may be lubricated to further improve press molding, and the type of lubricating film may be appropriately selected.

It is a figure which shows the relationship between a texture and a material. It is a figure which shows the relationship between the hot rolled sheet | seat structure and the r value of a product board. It is a figure which shows the relationship between a hot-rolled board structure | tissue and the total elongation of a product board.

Claims (4)

In mass%, Cr: 14 to 25%, C: 0.001 to 0.005%, Si: 0.01 to 0.20%, Mn: 0.01 to 0.20%, P: 0.01 -0.03%, S: 0.0005-0.0100%, N: 0.001-0.020%, Ti: 0.05-0.20%, Mo: 0.5-2.0%, B: 0.0002 to 0.0030% is contained, the balance is made of Fe and inevitable impurities, r ₄₅ and r ₉₀ are 1.5 or more, EL ₄₅ and EL ₉₀ are 30% or more, {111 } <112> Ferritic stainless steel sheet for fuel parts excellent in workability, characterized in that the orientation strength is 10 or more and {411} <148> orientation strength is 3 or more .
Here, r ₄₅ is the r value in the rolling direction and 45 ° direction, r ₉₀ is the r value in the direction perpendicular to the rolling direction, EL ₄₅ is the total elongation in the rolling direction and 45 ° direction, and EL ₉₀ is in the direction perpendicular to the rolling direction. Total growth. Furthermore, in mass%, Ni: 0.2-1.0%, Nb: 0.05-0.60%, Cu: 0.2-3.0%, V: 0.05-1.0%, mg: 0.0002~0.0030%, Al: 0.005~0.100 % of one or fuel component which is excellent in workability according to claim 1, characterized in that it contains two or more Ferritic stainless steel sheet. The cold-rolled material having a recrystallized grain size of 80 µm or less and a recrystallization rate of 90% or less is cold-rolled and subsequently annealed, and is excellent in workability according to claim 1 or 2 . Manufacturing method of ferritic stainless steel sheet for fuel parts . When a stainless steel slab is hot-rolled, continuous rolling is performed with a slab heating temperature of 1100 to 1250 ° C. and a ratio of the total rolling reduction of rough rolling to the total rolling reduction of finish rolling of 0.8 to 1.0. 4. The process according to claim 3 , wherein the heat treatment is performed at an end temperature of 700 to 900 [deg.] C., wound at 650 to 850 [deg.] C., and then subjected to cold rolling and annealing by omitting hot rolling plate annealing. Manufacturing method of ferritic stainless steel sheet for fuel parts .

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