JP7682672B2 - Ferritic stainless steel material, martensitic stainless steel material, ferritic-martensite dual-phase stainless steel material, their manufacturing methods, and corrosion-resistant members - Google Patents

Description

The present invention relates to ferritic stainless steel materials, martensitic stainless steel materials, ferritic-martensite dual-phase stainless steel materials, their manufacturing methods, and corrosion-resistant members.

Stainless steel materials have various excellent properties such as corrosion resistance, and are therefore used in a wide range of applications, such as automobile parts, building parts, and kitchen utensils.
Stainless steel materials are classified into steel plates, steel bars, steel strips, steel bars, steel pipes, etc., depending on the shape. Stainless steel plates, which are common stainless steel materials, are manufactured by the following process. For example, hot-rolled steel plates (thick plates) are manufactured by continuously casting molten iron, which is made by dissolving stainless steel raw materials, into slabs, hot rolling the slabs, and then annealing and pickling. Cold-rolled steel plates (thin plates) are manufactured by cold-rolling the hot-rolled steel plates, followed by annealing and pickling. In such a manufacturing process for stainless steel materials, pickling is performed to remove oxide scale formed on the surface of the stainless steel material. Hereinafter, removing the oxide scale formed on the surface of the stainless steel material will be referred to as "descaling".

However, there are cases where oxide scale cannot be sufficiently removed by pickling alone.
Therefore, in a typical descaling process, a mechanical pretreatment such as a scale breaker or shot blasting is performed to crack the oxide scale, and then the oxide scale is pickled to make it easier to remove (for example, Patent Documents 1 and 2). In addition, a method of immersing the stainless steel material in a salt bath as a chemical pretreatment is also known.

JP 2014-172077 A Japanese Unexamined Patent Publication No. 2-145785

However, in the conventional descaling process using pickling, the surface unevenness formed by the pretreatment and the surface roughness caused by the pickling cause the surface of the stainless steel material to turn white and lose its luster, resulting in a decrease in design. In particular, since a higher level of design (smoothness and luster) is required for cold-rolled steel material than for hot-rolled steel material, it is difficult to obtain the desired design in the conventional descaling process using pickling. In addition, since the oxide scale formed on the surface of ferritic stainless steel material is thick, it is difficult to introduce cracks by mechanical pretreatment, and pickling unevenness is also likely to occur. Furthermore, when the oxide scale is removed, inclusions are exposed on the surface of the stainless steel material, and these inclusions are a factor that reduces the corrosion resistance and fatigue properties of the stainless steel material.
In order to solve these problems, it is conceivable to polish the surface after the descaling process, but polishing the surface until it is smooth increases the amount of grinding, reducing the yield, and also reduces corrosion resistance and design properties due to polishing burns and entrapment of polishing debris. Furthermore, since inclusions are also present inside the stainless steel material, new inclusions will be exposed on the surface of the stainless steel material even if the surface is polished after the descaling process. Therefore, this method cannot be said to be effective.

In addition, martensitic stainless steel materials have a composition similar to that of ferritic stainless steel materials, but at high temperatures, an austenite phase is generated, resulting in a two-phase structure of ferrite and austenite, or a single austenite phase. Subsequent rapid cooling causes the austenite phase to undergo diffusionless transformation into the quenched martensite phase. Since this high-temperature heat treatment and rapid cooling are generally performed in an air atmosphere, in the manufacturing process of martensitic stainless steel materials and ferrite-martensite duplex stainless steel materials, oxide scale is formed in the same way as in ferritic stainless steel materials. The descaling process for these stainless steel materials also has the same issues as the conventional descaling process for ferritic stainless steel materials.

The present invention has been made to solve the above problems, and aims to provide ferritic stainless steel materials, martensitic stainless steel materials, and ferritic-martensite dual-phase stainless steel materials that have smooth and shiny surfaces and excellent corrosion resistance and fatigue properties, as well as methods for producing them and corrosion-resistant components that use them.

The inventors conducted intensive research to solve the above problems, and discovered that by controlling the composition of ferritic stainless steel, martensitic stainless steel, and ferritic-martensite duplex stainless steel and irradiating the material with laser light under specific conditions, it is possible to descale the material while maintaining the smoothness and gloss of the surface, and improve the corrosion resistance and fatigue properties by dissolving the inclusions on the surface. Based on this knowledge, the inventors produced and examined various ferritic stainless steel, martensitic stainless steel, and ferritic-martensite duplex stainless steel materials. As a result, the inventors discovered that ferritic stainless steel, martensitic stainless steel, and ferritic-martensite duplex stainless steel materials having a specified composition and a ratio D2/D1 of the number density D2 of inclusions on the surface to the number density D1 of a specified inclusion in the parent phase at a depth of 1/4 of the thickness from the surface can solve the above problems, and thus completed the present invention.

That is, the present invention has a composition, on a mass basis, of C: 0.001 to 0.150%, Si: 1.00% or less, Mn: 2.00% or less, P: 0.050% or less, S: 0.0300% or less, Ni: less than 2.00%, Cr: 11.00 to 30.00%, Mo: 6.00% or less, Cu: 0.60% or less, N: 0.050% or less, Al: 0.400% or less, Si + 2Al is less than 1.20%, and the balance is Fe and impurities;
The ferritic stainless steel material has a ratio D2/D1 of a number density D2 of inclusions at the surface to a number density D1 of inclusions having an equivalent circle diameter of 0.5 to 10 μm in a parent phase at a position at a depth of 1/4 of the thickness from the surface, which is 0.50 or less, and the number density D2 of the inclusions at the surface is 75 pieces/mm2 or less ^.

The present invention also provides a composition comprising, on a mass basis, C: 0.001 to 0.150%, Si: 1.00% or less, Mn: 2.00% or less, P: 0.050% or less, S: 0.0300% or less, Ni: less than 2.00%, Cr: 11.00 to 30.00%, Mo: 6.00% or less, Cu: 0.60% or less, N: 0.050% or less, Al: 0.400% or less, Si + 2Al is less than 1.20%, and the balance is Fe and impurities;
The martensitic stainless steel material has a ratio D2/D1 of a number density D2 of inclusions at the surface to a number density D1 of inclusions having an equivalent circle diameter of 0.5 to 10 μm in a parent phase at a position at a depth of 1/4 of the thickness from the surface, which is 0.50 or less, and the number density D2 of the inclusions at the surface is 75 pieces/mm2 or less ^.

The present invention also provides a composition comprising, on a mass basis, C: 0.001 to 0.150%, Si: 1.00% or less, Mn: 2.00% or less, P: 0.050% or less, S: 0.0300% or less, Ni: less than 2.00%, Cr: 11.00 to 30.00%, Mo: 6.00% or less, Cu: 0.60% or less, N: 0.050% or less, Al: 0.400% or less, Si + 2Al is less than 1.20%, and the balance is Fe and impurities;
The present invention relates to a ferritic-martensite duplex stainless steel material having a ratio D2/D1 of a number density D2 of inclusions at the surface to a number density D1 of inclusions having an equivalent circle diameter of 0.5 to 10 μm in a parent phase at a depth from the surface that is 1/4 of the thickness, the ratio being 0.50 or less, and the number density D2 of the inclusions at the surface being 75 pieces/mm2 or less ^.

The present invention also provides a method for producing the ferritic stainless steel material, the martensitic stainless steel material, or the ferritic-martensite duplex stainless steel material, comprising:
A descaling process includes irradiating a surface of a cold-rolled steel material with a laser beam to remove oxide scale formed on the surface of the cold-rolled steel material,
The laser beam is irradiated under conditions that allow the melting of a region of the cold-rolled steel material from the interface between the parent phase and the oxide scale to a depth of 0.50 to 10.00 μm.

Furthermore, the present invention relates to a corrosion-resistant member including the ferritic stainless steel material, the martensitic stainless steel material, or the ferritic-martensite dual-phase stainless steel material.

The present invention can provide ferritic stainless steel materials, martensitic stainless steel materials, and ferritic-martensite dual-phase stainless steel materials that have smooth and glossy surfaces and excellent corrosion resistance and fatigue properties, as well as methods for producing these materials and corrosion-resistant components that use these materials.

FIG. 1 is a schematic cross-sectional view of a stainless steel material according to an embodiment of the present invention. 1A and 1B are schematic cross-sectional views for explaining the difference between descaling by irradiation of laser light and descaling by a conventional method.

The following is a detailed description of the embodiments of the present invention. The present invention is not limited to the following embodiments, and it should be understood that modifications and improvements to the following embodiments, which are made based on the ordinary knowledge of those skilled in the art, fall within the scope of the present invention, without departing from the spirit of the present invention.
In this specification, the "%" designation for components means "% by mass" unless otherwise specified.

The ferritic stainless steel material, martensitic stainless steel material, and ferritic-martensite dual-phase stainless steel material (hereinafter collectively referred to as "stainless steel material") according to the embodiments of the present invention have a composition containing C: 0.001 to 0.150%, Si: 1.00% or less, Mn: 2.00% or less, P: 0.050% or less, S: 0.0300% or less, Ni: less than 2.00%, Cr: 11.00 to 30.00%, Mo: 6.00% or less, Cu: 0.60% or less, N: 0.050% or less, Al: 0.400% or less, Si + 2Al is less than 1.20%, and the balance is Fe and impurities.
Here, in this specification, "stainless steel material" means a material formed from stainless steel, and the shape of the material is not particularly limited. Examples of the shape of the material include plate (including strip), rod, and tube. In addition, the cross-sectional shape may be various shaped steel such as T-shaped and I-shaped. In addition, "impurities" mean components that are mixed in due to raw materials such as ores and scraps and various factors in the manufacturing process when manufacturing stainless steel materials industrially, and are acceptable within a range that does not adversely affect the present invention. For example, stainless steel materials may contain 0.02% or less of O as an impurity.
Note that "martensitic stainless steel material" and "ferritic-martensitic duplex stainless steel material" are equivalent to stainless steel material that has been subjected to quenching heat treatment, and are classified into one or the other depending on the volume ratio of the martensite phase. Also, "ferritic stainless steel material" is equivalent to stainless steel material that has not been subjected to quenching heat treatment.

In addition, the stainless steel material according to the embodiment of the present invention may further contain one or more selected from Ti: 0.001 to 0.500%, Nb: 0.001 to 1.000%, V: 0.001 to 1.000%, W: 0.001 to 1.000%, Zr: 0.001 to 1.000%, and Co: 0.001 to 1.200%.
Furthermore, the stainless steel material according to the embodiment of the present invention may further contain one or more selected from Ca: 0.0001 to 0.0100%, B: 0.0001 to 0.0080%, Sn: 0.001 to 0.500%, and REM: 0.200% or less.
Each component will be described in detail below.

<C: 0.001-0.150%>
If the C content is too high, the stainless steel becomes hard and the workability is reduced, and in addition, when the stainless steel is subjected to heat effects such as welding, sensitization occurs, and the corrosion resistance of the stainless steel material is reduced. Therefore, the upper limit of the C content is controlled to 0.150%, preferably 0.100%, more preferably 0.060%, and even more preferably 0.040%. On the other hand, if the C content is too low, the workability is deteriorated and the refining cost is increased. Therefore, the lower limit of the C content is controlled to 0.001%, preferably 0.002%, more preferably 0.005%, and even more preferably 0.010%.

<Si: 1.00% or less>
If the content of Si is too high, the stainless steel material becomes hard and the workability of the stainless steel material decreases. Therefore, the upper limit of the content of Si is controlled to 1.00%, preferably 0.80%, more preferably 0.70%, and even more preferably 0.60%. On the other hand, the lower limit of the content of Si is not particularly limited, but is preferably 0.01%, more preferably 0.05%, and even more preferably 0.10%.

<Mn: 2.00% or less>
Mn is an element that improves the heat resistance of stainless steel materials. However, if the content of Mn is too high, the corrosion resistance of stainless steel materials will decrease. In addition, since Mn is an austenite phase (γ phase) forming element, it generates γ phase (martensite phase at room temperature) at high temperatures, and the workability of stainless steel materials will also decrease. Therefore, the upper limit of the Mn content is controlled to 2.00%, preferably 1.50%, more preferably 1.20%, and even more preferably 1.00%. On the other hand, the lower limit of the Mn content is not particularly limited, but is preferably 0.01%, more preferably 0.05%, and even more preferably 0.10%.

<P: 0.050% or less>
If the P content is too high, the corrosion resistance and workability of the stainless steel material will decrease. Therefore, the upper limit of the P content is controlled to 0.050%, preferably 0.035%, more preferably 0.030%, and even more preferably 0.020%. On the other hand, the lower limit of the P content is not particularly limited, but is preferably 0.001%, more preferably 0.005%, and even more preferably 0.010%.

<S: 0.0300% or less>
If the S content is too high, the hot workability is reduced, the manufacturability of the stainless steel material is reduced, and the corrosion resistance is also adversely affected. Therefore, the upper limit of the S content is controlled to 0.0300%, preferably 0.0100%, more preferably 0.0050%, and even more preferably 0.0010%. On the other hand, the lower limit of the S content is not particularly limited, but is preferably 0.0001%, more preferably 0.0002%, and even more preferably 0.0003%.

<Ni: less than 2.00%>
Ni is an element that improves the corrosion resistance of stainless steel materials. However, since Ni is an austenite phase (γ phase) forming element like Mn, if the content is too high, it will generate a γ phase at high temperatures (martensite phase at room temperature), and the workability of the stainless steel material will decrease. In addition, since Ni is an expensive element, it will also lead to an increase in manufacturing costs. Therefore, the Ni content is controlled to less than 2.00%, preferably 1.00% or less, more preferably 0.50% or less, and even more preferably 0.35% or less. On the other hand, the lower limit of the Ni content is not particularly limited, but is preferably 0.01%, more preferably 0.03%, and even more preferably 0.05%.

<Cr: 11.00-30.00%>
If the Cr content is too high, the refining cost will increase, and the stainless steel material will become hard due to solid solution strengthening, resulting in a decrease in workability. Therefore, the upper limit of the Cr content is controlled to 30.00%, preferably 24.00%, more preferably 22.00%, and even more preferably 18.00%. On the other hand, if the Cr content is too low, sufficient corrosion resistance will not be obtained. Therefore, the lower limit of the Cr content is controlled to 11.00%, preferably 13.00%, more preferably 14.00%, and even more preferably 15.00%.

<Mo: 6.00% or less>
Mo is an element that improves the corrosion resistance of stainless steel materials. Since Mo is expensive, if the Mo content is too high, the manufacturing cost increases. Therefore, the upper limit of the Mo content is controlled to 6.00%, preferably 5.00%, more preferably 3.00%, and even more preferably 2.00%. On the other hand, the lower limit of the Mo content is not particularly limited, but is preferably 0.10%, more preferably 0.50%, and even more preferably 1.00%.

<Cu: 0.60% or less>
Cu is an element that improves the workability of stainless steel materials. If the Cu content is too high, the corrosion resistance of the stainless steel material is reduced, and a low melting point phase is formed during casting, resulting in a reduction in hot workability. Therefore, the upper limit of the Cu content is controlled to 0.60%, preferably 0.40%, and more preferably 0.20%. On the other hand, the lower limit of the Cu content is not particularly limited, but is preferably 0.02%, and more preferably 0.04%.

<N: 0.050% or less>
N is an element that improves corrosion resistance. If the N content is too high, the stainless steel material becomes hard and the workability decreases. Therefore, the upper limit of the N content is controlled to 0.050%, preferably 0.040%, more preferably 0.030%, and further preferably 0.020%. On the other hand, the lower limit of the N content is not particularly limited, but is preferably controlled to 0.001%, preferably 0.005%, and more preferably 0.010%.

<Al: 0.400% or less>
Al is an element added as necessary for deoxidation in the refining process, and improves corrosion resistance and heat resistance. If the content of Al is too high, the amount of inclusions generated increases, degrading the quality. Therefore, the upper limit of the content of Al is controlled to 0.400%, preferably 0.100%, and more preferably 0.050%. On the other hand, the lower limit of the content of Al is not particularly limited, but is preferably 0.001%, and more preferably 0.005%.

<Si + 2Al: less than 1.20%>
The stainless steel material according to the embodiment of the present invention is intended to have a low content of Si and Al. Specifically, Si+2Al (each element symbol represents the content of each element) is less than 1.20%, preferably 1.10% or less, more preferably 1.00% or less, and even more preferably 0.90% or less. The lower limit of Si+2Al is not particularly limited, but is preferably 0.01%, more preferably 0.05%, and even more preferably 0.10%.

<Ti: 0.001 to 0.500%>
Ti is an element that improves corrosion resistance and intergranular corrosion resistance by bonding with C and N, and is added as necessary. From the viewpoint of obtaining the effect of Ti, the lower limit of the Ti content is controlled to 0.001%, preferably 0.005%. On the other hand, if the Ti content is too high, it causes surface defects, leading to a decrease in quality and a decrease in the workability of the stainless steel material. Therefore, the upper limit of the Ti content is controlled to 0.500%, preferably 0.300%, more preferably 0.100%.

<Nb: 0.001 to 1.000%>
Like Ti, Nb is an element that improves corrosion resistance and intergranular corrosion resistance by combining with C and N, and is added as necessary. From the viewpoint of obtaining the effect of Nb, the lower limit of the Nb content is controlled to 0.001%, preferably 0.004%, and more preferably 0.010%. On the other hand, if the Nb content is too high, the workability of the stainless steel material is reduced. Therefore, the upper limit of the Nb content is controlled to 1.000%, preferably 0.600%, and more preferably 0.060%.

<V: 0.001-1.000%>
V is an element that improves corrosion resistance and is added as necessary. From the viewpoint of obtaining the effect of V, the lower limit of the V content is controlled to 0.001%, preferably 0.010%. On the other hand, if the V content is too high, the workability of the stainless steel material is reduced. Therefore, the upper limit of the V content is controlled to 1.000%, preferably 0.200%.

<W: 0.001-1.000%>
W is an element that improves high-temperature strength and corrosion resistance, and is added as necessary. From the viewpoint of obtaining the effect of W, the lower limit of the W content is controlled to 0.001%, preferably 0.010%. On the other hand, if the W content is too high, the stainless steel material becomes hard and the workability decreases, and the surface defects increase, degrading the surface quality of the stainless steel material. Therefore, the upper limit of the W content is controlled to 1.000%, preferably 0.300%.

<Zr: 0.001 to 1.000%>
Zr is an element that improves oxidation resistance and intergranular corrosion resistance by combining with C and N, and is added as necessary. From the viewpoint of obtaining the effect of Zr, the lower limit of the Zr content is controlled to 0.001%, preferably 0.010%. On the other hand, if the Zr content is too high, the workability of the stainless steel material is reduced. Therefore, the upper limit of the Zr content is controlled to 1.000%, preferably 0.200%, more preferably 0.050%.

<Co:0.001-1.200%>
Co is an element that improves heat resistance and is added as necessary. From the viewpoint of obtaining the effect of Co, the lower limit of the Co content is controlled to 0.001%, preferably 0.010%. On the other hand, since Co is expensive, if the Co content is too high, the manufacturing cost increases. Therefore, the upper limit of the Co content is controlled to 1.200%, preferably 0.400%.

<Ca: 0.0001 to 0.0100%>
Ca is an element that improves the hot workability of stainless steel materials and is added as necessary. Ca is also an element that improves intergranular oxidation resistance by forming sulfides and suppressing grain boundary segregation of S. From the viewpoint of obtaining the effect of Ca, the lower limit of the Ca content is controlled to 0.0001%, preferably 0.0003%. On the other hand, if the Ca content is too high, the number of inclusions increases, leading to a decrease in workability. Therefore, the upper limit of the Ca content is controlled to 0.0100%, preferably 0.0050%.

<B: 0.0001 to 0.0080%>
B is an element that improves the hot workability of stainless steel materials and is added as necessary. B is also an element that improves the secondary workability of stainless steel materials by grain boundary strengthening. From the viewpoint of obtaining the effect of B, the lower limit of the content of B is controlled to 0.0001%, preferably 0.0003%, and more preferably 0.0005%. On the other hand, if the content of B is too high, it leads to a decrease in weldability and fatigue strength. Therefore, the upper limit of the content of B is controlled to 0.0080%, preferably 0.0040%, and more preferably 0.0025%.

<Sn: 0.001-0.500%>
Sn is an element that improves corrosion resistance and high-temperature strength, and is added as necessary. From the viewpoint of obtaining the effect of Sn, the lower limit of the Sn content is controlled to 0.001%, preferably 0.002%. On the other hand, if the Sn content is too high, a low melting point phase is formed, and the hot workability of the stainless steel material is reduced. Therefore, the upper limit of the Sn content is controlled to 0.500%, preferably 0.100%, more preferably 0.050%.

<REM: 0.200% or less>
REM (rare earth elements) are elements that improve the hot workability of stainless steel materials, similar to B and Ca, and are added as necessary. REM also forms sulfides that are difficult to dissolve, and is an element that improves corrosion resistance by suppressing the generation of MnS, which is a corrosion starting point. However, if the REM content is too high, it leads to an increase in manufacturing costs. Therefore, the upper limit of the REM content is controlled to 0.200%, preferably 0.100%. On the other hand, the lower limit of the REM content is not particularly limited, but is preferably 0.001%, more preferably 0.010%, from the viewpoint of obtaining the effect of REM.
REM is a collective term for two elements, scandium (Sc) and yttrium (Y), and 15 elements (lanthanoids) from lanthanum (La) to lutetium (Lu). These may be used alone or as a mixture.

In the stainless steel material according to the embodiment of the present invention, the ratio D2/D1 of the number density D2 of inclusions having a circle-equivalent diameter of 0.5 to 10 μm at the surface (e.g., surface B in FIG. 1) to the number density D1 of inclusions having a circle-equivalent diameter of 0.5 to 10 μm in the parent phase (e.g., position C in FIG. 1) at a depth of 1/4 of the thickness from the surface (e.g., surface B in FIG. 1) is 0.50 or less, preferably 0.49 or less, and more preferably 0.48 or less. By controlling the ratio D2/D1 of the number densities of the inclusions within such a range, the proportion of inclusions present at the surface can be reduced compared to inclusions present in the parent phase, and therefore the corrosion resistance and fatigue properties of the stainless steel material can be improved.
The lower limit of the ratio D2/D1 of the number densities of the inclusions is not particularly limited because the smaller the ratio, the greater the effect of improving the corrosion resistance and fatigue properties. For example, the lower limit is 0.01.

The number density D1 of inclusions having a circle equivalent diameter of 0.5 to 10 μm in the parent phase at a position from the surface of the stainless steel material to a quarter of the thickness (hereinafter referred to as "number density D1 of inclusions in the parent phase") can be calculated as follows. First, any location (10 or more fields of view) at a position from the surface of the stainless steel material to a quarter of the thickness (parent phase) is photographed with an electron microscope. Next, the photographed image is binarized to separate inclusions having a circle equivalent diameter of 0.5 to 10 μm (black) and the parent phase (white), the black regions are counted to determine the number of inclusions, and the number of inclusions thus obtained is divided by the area of the observation field to calculate the number density D1 of inclusions in the parent phase.
Similarly, the number density D2 of inclusions having an equivalent circle diameter of 0.5 to 10 μm on the surface of the stainless steel material (hereinafter referred to as "number density D2 of inclusions on the surface") can be calculated by photographing any location (10 or more fields of view) on the surface of the stainless steel material with an electron microscope and dividing the number of inclusions obtained in the same manner as above by the area of the observed fields of view.
Here, since most of the inclusions have an equivalent circle diameter in the range of 0.5 to 10 μm, the number of inclusions in this size range was counted and defined as the number densities D1 and D2 of the inclusions. The equivalent circle diameter means the diameter of a circle when the area of each observed black region is converted into a circle having the same area.

As the electron microscope, a Schottky scanning electron microscope SU5000 manufactured by Hitachi High-Tech Corporation can be used. Furthermore, inclusions can be identified using an EDX detector EMAX3.3SP2 manufactured by Oxford Instruments Ltd. that is attached to the electron microscope. Furthermore, analysis software (AZtecSteel) manufactured by Oxford Instruments Ltd. can be used for image processing.

The density D1 of the inclusions in the matrix is, for example, about 80 to 300 pieces/mm ² .

The number density D2 of the inclusions on the surface is preferably 75 pieces/mm ² or less, and more preferably 60 pieces/mm ² or less. By controlling the number density D2 of the inclusions on the surface within this range, the amount of inclusions present on the surface of the stainless steel material can be reduced, and therefore the corrosion resistance and fatigue strength of the stainless steel material can be stably improved.
The lower limit of the number density D2 of the inclusions on the surface is not particularly limited because the smaller the density, the greater the effect of improving the corrosion resistance and fatigue properties. For example, the lower limit is 10 pieces/ ^mm2 .

The inclusions are non-metallic inclusions (particularly sulfide-based and oxide-based inclusions), and specific examples thereof include MnS, TiN, TiC, NbN, NbC, CaO, SiO ₂ , Al ₂ O ₃ and complex compounds thereof.

The stainless steel material according to the embodiment of the present invention preferably has a molten and solidified layer on the surface.
Here, as an example, a schematic cross-sectional view of a stainless steel material according to an embodiment of the present invention is shown in FIG.
As shown in Figure 1, the stainless steel material 10 comprises a parent phase 11 and a molten solidified layer 12 formed on a surface A of the parent phase 11. The parent phase 11 contains inclusions 13. The molten solidified layer 12 may also contain inclusions 13, but there are few inclusions 13 exposed on a surface B of the molten solidified layer 12. This is because the inclusions 13 exposed on the surface B are dissolved by descaling with a laser beam.

The thickness of the molten solidified layer is not particularly limited, but is preferably 0.50 to 10.00 μm, more preferably 1.00 to 10.00 μm, and even more preferably 2.00 to 10.00 μm. If the thickness of the molten solidified layer is less than 0.50 μm, the inclusions are likely to be insufficiently dissolved. As a result, the inclusions exposed on the surface tend to increase, and the corrosion resistance and fatigue properties of the stainless steel material tend to decrease. On the other hand, if the thickness of the molten solidified layer exceeds 10.00 μm, the surface tends to become rough, making it difficult to obtain a smooth and glossy surface.

The stainless steel material according to the embodiment of the present invention has a surface arithmetic mean roughness Ra of preferably 0.01 to 0.40 μm, more preferably 0.01 to 0.30 μm, and even more preferably 0.01 to 0.20 μm. By controlling the surface arithmetic mean roughness Ra within such a range, the smoothness of the stainless steel material can be ensured.
Here, in this specification, "arithmetic mean roughness Ra" means the arithmetic mean roughness Ra measured in accordance with JIS B0601:2013.

The stainless steel material according to the embodiment of the present invention has a 60 degree specular gloss Gs (60°) of the surface of preferably 200 to 750%, more preferably 300 to 750%, and even more preferably 400 to 750%. By controlling the 60 degree specular gloss Gs (60°) of the surface within such a range, the gloss of the stainless steel material can be ensured.
In this specification, "60 degree specular gloss Gs (60°)" means 60 degree specular gloss Gs (60°) measured in accordance with JIS Z8741:1997.

The stainless steel material according to the embodiment of the present invention is preferably a stainless cold-rolled steel material, and more preferably a stainless cold-rolled steel sheet. In this specification, the cold-rolled steel material and cold-rolled steel sheet after the oxide scale has been removed are referred to as "stainless cold-rolled steel material" and "stainless cold-rolled steel sheet", and the cold-rolled steel material and cold-rolled steel sheet before the oxide scale has been removed are referred to as "cold-rolled steel material" and "cold-rolled steel sheet".
Hereinafter, the stainless steel material according to the embodiment of the present invention will be described by taking as an example a stainless cold-rolled steel sheet.
The thickness (sheet thickness) of the stainless steel cold rolled steel sheet according to one embodiment of the present invention is not particularly limited, but is preferably less than 3 mm, more preferably 2.5 mm or less, and even more preferably 2 mm or less. The lower limit is, for example, 0.1 mm, and may be 0.3 mm.

The stainless steel cold-rolled steel sheet according to one embodiment of the present invention can be manufactured by using a method known in the art, except for the descaling process in which a laser beam is irradiated onto the surface of a cold-rolled steel sheet having the above-mentioned composition, and the oxide scale formed on the surface is removed.

The method for producing cold-rolled steel sheet having the above composition is not particularly limited, but for example, it can be produced as follows. First, stainless steel having the above composition is melted and forged or cast to obtain a steel slab. Next, the steel slab is hot-rolled, annealed, and then descaled. The method for descaling is not particularly limited, and can be performed using pickling, polishing, or laser light. Next, the descaled hot-rolled steel sheet is cold-rolled and annealed to obtain a cold-rolled steel sheet. The conditions for each process are not particularly limited, and may be adjusted appropriately depending on the composition of the stainless steel, etc.

The cold-rolled steel sheet is irradiated with laser light under conditions that allow melting of the region from the interface between the parent phase and the oxide scale in the cold-rolled steel sheet to a depth of 0.50 to 10.00 μm, preferably 1.00 to 10.00 μm, more preferably 2.00 to 10.00 μm. By irradiating with laser light under such conditions, the oxide scale can be removed while maintaining the smoothness and gloss of the surface, and the inclusions on the surface are dissolved by the heat effect to form a molten solidified layer on the surface, thereby improving the corrosion resistance and fatigue properties. If the irradiation conditions allow melting only to a region less than 0.50 μm deep from the surface of the cold-rolled steel sheet, the inclusions are not sufficiently dissolved, and the inclusions exposed on the surface cannot be sufficiently reduced, resulting in a decrease in the corrosion resistance and fatigue properties of the stainless steel cold-rolled steel sheet. If the irradiation conditions allow melting of the region from the surface of the cold-rolled steel sheet to a depth of more than 10.00 μm, the surface of the stainless steel cold-rolled steel sheet becomes rough, and a smooth and glossy surface cannot be obtained.

FIG. 2 is a schematic cross-sectional view for explaining the difference between descaling by laser light irradiation and descaling by a conventional method.
2(a), a cold-rolled steel material (cold-rolled steel sheet) 20 has an oxide scale 21 formed on the surface of a parent phase 11. In addition, inclusions 13 are present at an interface D between the parent phase 11 and the oxide scale 21 (the surface of the parent phase 11).
When descaling (removal of oxide scale 21) is performed by a conventional method (pickling and/or polishing), the inclusions 13 present at the interface D between the parent phase 11 and the oxide scale 21 are exposed at the surface E, as shown in Fig. 2(b) . Even if the surface layer of the parent phase 11 is removed together with the oxide scale 21 in order to remove the inclusions 13 present at the interface D between the parent phase 11 and the oxide scale 21, the inclusions 13 present inside the parent phase 11 end up being exposed at the surface E. Therefore, it is difficult to reduce the inclusions 13 exposed at the surface E with the conventional method.

In contrast, when descaling is performed by irradiating a laser beam, as shown in FIG. 2(c), the oxide scale 21 is removed and the inclusions 13 present at the interface D between the parent phase 11 and the oxide scale 21 are dissolved. As a result, a molten solidified layer 12 is formed on the surface of the parent phase 11, and the number of inclusions 13 exposed on the surface B is reduced. The reduction in the number of inclusions 13 occurs when the inclusions 13 near the surface melt when the molten solidified layer 12 is formed, become diluted with the parent phase components, and rapidly solidify before reprecipitation. In addition, in the vicinity of the molten solidified layer 12, even in the parts that were not directly melted, the inclusions 13 are dissolved due to the increase in temperature, resulting in a reduction in the size of the inclusions 13 and a reduction in the number of inclusions 13. Even if the inclusions are not completely melted and rendered harmless, they are partially melted and the circle equivalent diameter of the inclusions 13 is reduced, improving corrosion resistance and fatigue strength.

The conditions of the laser irradiation may be adjusted according to the device used, taking into consideration the following points.
(Type of laser light)
When continuous wave laser light is used, the energy required to remove the oxide scale becomes large, the required power becomes large, and the area affected by heat becomes too large, making it difficult to control the thickness of the molten solidified layer. Therefore, a pulsed laser light that can apply heat instantaneously is preferred.
(wavelength)
In general, the reflectance of a material to light depends on the wavelength, and selecting a wavelength with a low reflectance increases the heat input, making it easier for the oxide scale to evaporate. Therefore, by selecting a wavelength with a high reflectance for the parent phase and a low reflectance for the oxide, it is possible to selectively evaporate and remove the oxide scale without melting the parent phase more than necessary.
(Pulse Width)
The pulse width represents the time during which one pulse is irradiated, and the narrower the pulse width, the more instantaneous heating occurs. With a narrow pulse width, ablation occurs before the heat input by the laser is transmitted to the surroundings, so the ablation threshold is small and the thermal impact on the parent phase is reduced. When laser irradiation is performed under conditions that cause the parent phase to melt, the narrower the pulse width, the more rapid cooling occurs and the more suppressed the reprecipitation of molten inclusions. However, the pulse width is mainly determined by the performance of the oscillator, and since devices capable of oscillating with a short pulse width are expensive, it is preferable to select a short pulse width within the specifications of the device.
(Oscillation frequency)
The shorter the pulse width, the higher the oscillation frequency can be, and the higher the oscillation frequency, the more pulses are emitted per unit time, which improves the rate at which oxide scale is removed. Therefore, it is preferable to select a high oscillation frequency within the range of the device specifications.

(scan frequency)
The scanning frequency represents the moving speed of the pulse irradiation position in the planar direction, and the higher the scanning frequency, the faster the oxide scale removal speed becomes, but if the frequency is too high, gaps will be generated between the pulse irradiation positions, and the oxide scale will remain, reducing the descaling rate. Therefore, it is preferable to increase the scanning frequency within a range where the descaling rate can be maintained.
(Laser beam diameter)
The larger the beam diameter, the wider the irradiation range, i.e., the range that can be descaled with one pulse, and the better the descaling efficiency, but the lower the energy density (fluence) of one pulse. It is preferable to increase the beam diameter within a range that maintains a fluence that can evaporate and remove oxide scale.
(Fluence)
By irradiating the laser beam with a fluence exceeding the ablation threshold of the oxides that make up the oxide scale, the oxide scale can be evaporated and removed. The higher the fluence, the greater the thickness of the oxide scale that can be removed, but if the fluence is too high, not only the oxide scale but also the parent phase will be evaporated and removed. In addition, the pulsed laser has less thermal impact than the continuous wave laser, but the higher the fluence, the greater the heat input to the parent phase, and the larger the molten zone and heat-affected zone. Therefore, the fluence can be adjusted within a range that does not melt the parent phase more than necessary, taking into account the balance between the characteristics of the oxide scale to be removed (thickness, structure, composition, etc.) and the heat input to the parent phase. If the fluence distribution is different within the beam spot, it can be controlled using the average fluence.

The stainless steel material according to the embodiment of the present invention having the above characteristics has excellent corrosion resistance and can be used as a corrosion-resistant component. This stainless steel material also has excellent fatigue properties, making it suitable for use in corrosion-resistant components that require fatigue properties. Furthermore, this stainless steel material has a smooth and glossy surface and excellent design, making it suitable for use in corrosion-resistant components that require design properties.

The corrosion-resistant member according to the embodiment of the present invention includes the above-mentioned stainless steel material.
The stainless steel material used for the corrosion-resistant member may be processed into various shapes by methods known in the art.
The corrosion-resistant member according to the embodiment of the present invention may further include members other than the above-mentioned stainless steel material.
Examples of corrosion-resistant members include, but are not limited to, automobile parts, building parts, kitchen utensils, and the like.

The present invention will be described in detail below with reference to examples, but the present invention should not be construed as being limited to these.

30 kg of stainless steel having the composition of steel types A to E shown in Table 1 (the balance being Fe and impurities) was melted by vacuum melting, forged into a 30 mm thick steel billet, heated at 1230°C for 2 hours, hot rolled to a thickness of 3 mm, and annealed at 1100°C for 5 minutes in an air atmosphere to obtain a hot-rolled steel sheet. The hot-rolled steel sheet was cut into a size of 50 mm (rolling direction) x 50 mm (width direction) by processing, and then pickled and descaled. The pickled and descaled steel sheet was immersed in a hydrofluoric acid-nitric acid aqueous solution containing 50 g/L hydrofluoric acid and 150 g/L nitric acid in a thermostatic bath at 60°C for 60 to 600 seconds, immediately rinsed with running water, and naturally dried. The specific immersion times were 60 seconds for steel type A, 100 seconds for steel type B, 400 seconds for steel type C, 600 seconds for steel type D, and 60 seconds for steel type E. The hot-rolled steel sheets were then cold-rolled from 3 mm to 1 mm in thickness and annealed at 1100°C for 5 minutes in an air atmosphere to obtain cold-rolled steel sheets (ferritic stainless steel materials). In addition, for steel types A and B, the cold-rolled steel sheets were further heated at 1000°C for 3 minutes in an air atmosphere, then water-cooled, and subjected to quenching heat treatment to obtain cold-rolled steel sheets (martensitic stainless steel materials and ferritic-martensitic dual-phase stainless steel materials) in which a martensite phase was generated. The obtained cold-rolled steel sheets were used in the following examples and comparative examples.

(Examples 1 to 7)
Cold-rolled steel sheets having each of the steel compositions were subjected to a descaling process by irradiation with a laser beam.
The laser light was irradiated using a commercially available device (LaserClear50A manufactured by IHI Inspection & Measurement Co., Ltd.). The cold-rolled steel sheet was placed on the movable stage of this device, and while moving at 0.2 m/min along the rolling direction, the cold-rolled steel sheet was scanned at a constant speed from above the sheet width direction to irradiate once with the pulsed laser light. The scan width per scan was 25 mm. The irradiation conditions of the pulsed laser light were as follows.
Wavelength: 1085nm
Pulse width: 220ns
Oscillation frequency: 60kHz
Scan frequency: 100Hz
Laser beam diameter: 90 μm
Average fluence: 8 J/ ^cm2

(Comparative Example 1)
A cold-rolled steel sheet having the composition of steel type A was subjected to a descaling process by pickling.
The pickling was carried out as follows: A hydrofluoric/nitric acid aqueous solution containing 30 g/L of hydrofluoric acid and 100 g/L of nitric acid was kept at 60° C. in a thermostatic chamber, and the cold-rolled steel sheet was immersed for 600 seconds, and then immediately rinsed with running water and naturally dried.

(Comparative Example 2)
The cold-rolled steel sheet after the descaling process obtained in Comparative Example 1 was subjected to belt polishing using SiC polishing paper (grit #400) and water-soluble grinding oil. The grinding depth was set to a depth of 20 μm from the surface.

The following evaluations were carried out on the stainless steel cold-rolled sheets obtained in the above examples and comparative examples after the descaling process.

(Number density of inclusions D1, D2)
A 50 mm square test piece was cut out from the center of the width and length of the stainless steel cold rolled steel sheet obtained in the above examples and comparative examples, and an arbitrary part of the surface was photographed at 200 times using a Schottky scanning electron microscope SU5000 manufactured by Hitachi High-Tech Corporation. In addition, the surface of this test piece was polished to remove 1/4 of the thickness (250 μm), and the mother phase at a position where the depth from the surface is 1/4 of the thickness was exposed, and then an arbitrary part of this exposed surface was photographed in the same manner as above. The photographing was performed in 10 fields of view, with 0.48 mm x 0.64 mm (0.3072 mm ² ) as one field of view. Next, the photographed image was binarized using analysis software (AZtecSteel) manufactured by Oxford Instruments Co., Ltd., and divided into inclusions (black) with a circle equivalent diameter of 0.5 to 10 μm and the mother phase (white). The image analysis conditions were as follows.
Resolution: 4096
Minimum detection size: 8 pixels (0.5 μm)
Inclusion color threshold: 47-24057
Anything less than 8 pixels was excluded as noise.
Next, the number of inclusions was calculated by counting black regions having a circle equivalent diameter of 0.5 to 10 μm in the binarized image, and the number of inclusions thus obtained was divided by the area of the observation field to calculate the number densities D1 and D2 of the inclusions. The results of the number densities D1 and D2 of the inclusions were taken as the average value of the results in each field.
In addition, based on the calculated number densities D1 and D2 of the inclusions, the ratio of the number densities of the inclusions D2/D1 was calculated.

(Thickness of melted and solidified layer)
The stainless steel cold rolled sheet was cut in the thickness direction (direction perpendicular to the surface) parallel to the rolling direction, and the composition image of the cut surface was observed with an electron microscope up to 10,000 times, and the melted solidified layer was identified from the difference in contrast and its thickness was measured. The thickness was measured at 10 random points, and the average value was used as the result.

(Surface roughness measurement)
The arithmetic mean roughness Ra of the surface of the stainless steel cold rolled steel sheet was measured using a contact type surface roughness meter (Surfcom 2800 manufactured by Tokyo Seimitsu Co., Ltd.) in accordance with JIS B0601:2013. The arithmetic mean roughness Ra was measured at five points excluding the range from the end to 5 mm with a reference length of 4 mm, and the average value was used as the evaluation result. Note that each measurement position was separated by 5 mm or more.

(Gloss Measurement)
The 60-degree specular gloss Gs (60°) of the surface of the stainless steel cold-rolled steel sheet was measured using a gloss meter (PG-1M manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS Z8741:1997. The 60-degree specular gloss Gs (60°) was measured at five points excluding the range up to 5 mm from the end, and the average value was used as the evaluation result. The measurement positions were separated by 5 mm or more.

(Corrosion resistance test)
The corrosion resistance test was a composite cycle test according to JASO M609 and M610. Specifically, a salt-dry-wet cycle test was performed in which salt spray, drying, and wetting were repeated. In the salt-dry-wet cycle test, a cycle of spraying a 5% NaCl aqueous solution (at 35°C for 2 hours), drying (at 30% relative humidity and 60°C for 4 hours), and wetting (at 95% relative humidity and 50°C for 2 hours) was performed on the stainless steel cold-rolled steel sheet, and after washing and drying at the end of each cycle, the surface of the stainless steel cold-rolled steel sheet was observed and the rust area ratio was calculated. The number of cycles at which the rust area ratio became 10% or more was defined as the number of corrosion occurrence cycles.
The calculation of the rust area ratio was performed as follows. The surface of the stainless steel cold-rolled steel sheet after the salt-dry-wet cycle test was photographed, and the ratio of the area of the rusted part in the central 25 mm x 25 mm range excluding the end face was calculated. The area of the rusted part was calculated by binarizing the photograph of the surface of the stainless steel cold-rolled steel sheet by image analysis, calculating the area per pixel, and then counting the number of pixels of the rusted part. The rust area ratio was calculated by the following formula.
Rust area rate (%)=area of rusted part (mm ² )/total area of observed part (625 mm ² )×100
In this evaluation, the improvement rate of the number of cycles to corrosion occurrence was calculated for the stainless cold-rolled steel sheets of Examples 1 to 7 and Comparative Example 1, based on the number of cycles to corrosion occurrence for the stainless cold-rolled steel sheet of Comparative Example 2. The improvement rate of the calculated number of cycles to corrosion occurrence was evaluated as "◯" when it was 20% or more and less than 20%, as "△" when it was 10% or more and less than 20%, and as "X" when it was less than 10%.

(Fatigue property test)
The fatigue property test was performed in accordance with JIS Z2275:1978, and a plane bending fatigue test was performed. Specifically, a test piece was obtained by cutting a piece of stainless steel cold rolled steel sheet with a width direction length of 30 mm and a rolling direction length of 90 mm, and forming an R part with a radius of 30 mm on both ends in the width direction. The test piece was attached to a plane bending tester, and a fatigue test was performed with a repetition number of ^107. This fatigue test was performed on two or more test pieces for each stress stage, and the time strength was measured.
In this evaluation, the improvement rates of time strength were calculated for the stainless cold rolled steel sheets of Examples 1 to 7 and Comparative Example 1, based on the fatigue strength of the stainless cold rolled steel sheet of Comparative Example 2. The calculated improvement rates of time strength of 10% or more were marked as "good", and those of less than 10% were marked as "poor".
The results of the above evaluations are shown in Table 2.

As shown in Table 2, the stainless cold rolled steel sheets of Examples 1 to 7, in which the ratio D2/D1 of the number densities of inclusions is 0.50 or less, have a surface arithmetic mean roughness Ra of 0.01 to 0.40 μm and a surface 60-degree specular gloss Gs (60°) of 200 to 750%, and are confirmed to have a smooth and glossy surface. Furthermore, the stainless cold rolled steel sheets of Examples 1 to 7 have improved corrosion resistance and fatigue properties compared to the stainless cold rolled steel sheet of Comparative Example 2.
In contrast, the stainless cold-rolled steel sheet of Comparative Example 1 was descaled by pickling, and therefore the ratio D2/D1 of the number densities of inclusions exceeded 0.50. Therefore, the stainless cold-rolled steel sheet of Comparative Example 1 did not have sufficiently improved corrosion resistance and fatigue properties compared to the stainless cold-rolled steel sheet of Comparative Example 2.

As can be seen from the above results, the present invention can provide ferritic stainless steel materials, martensitic stainless steel materials, and ferritic-martensite dual-phase stainless steel materials that have smooth and glossy surfaces and excellent corrosion resistance and fatigue properties, as well as methods for producing these materials and corrosion-resistant components that use these materials.

Reference Signs List 10 Stainless steel material 11 Parent phase 12 Melted and solidified layer 13 Inclusions 20 Cold-rolled steel material 21 Oxide scale

Claims (15)

The composition includes, on a mass basis, C: 0.001 to 0.150%, Si: 1.00% or less, Mn: 2.00% or less, P: 0.050% or less, S: 0.0300% or less, Ni: less than 2.00%, Cr: 11.00 to 30.00%, Mo: 6.00% or less, Cu: 0.60% or less, N: 0.050% or less, Al: 0.400% or less, Si+2Al is less than 1.20%, and the balance is Fe and impurities;
A ferritic stainless steel material, wherein a ratio D2/D1 of a number density D2 of inclusions at the surface to a number density D1 of inclusions having an equivalent circle diameter of 0.5 to 10 μm in a parent phase at a position at a depth of 1/4 of the thickness from the surface is 0.50 or less, and the number density D2 of the inclusions at the surface is 75 pieces/mm2 ^or less . The ferritic stainless steel material according to claim 1, further comprising, by mass, one or more selected from Ti: 0.001-0.500%, Nb: 0.001-1.000%, V: 0.001-1.000%, W: 0.001-1.000%, Zr: 0.001-1.000%, and Co: 0.001-1.200%. The ferritic stainless steel material according to claim 1 or 2, further comprising, by mass, one or more selected from Ca: 0.0001-0.0100%, B: 0.0001-0.0080%, Sn: 0.001-0.500%, and REM: 0.200% or less. The composition includes, on a mass basis, C: 0.001 to 0.150%, Si: 1.00% or less, Mn: 2.00% or less, P: 0.050% or less, S: 0.0300% or less, Ni: less than 2.00%, Cr: 11.00 to 30.00%, Mo: 6.00% or less, Cu: 0.60% or less, N: 0.050% or less, Al: 0.400% or less, Si+2Al is less than 1.20%, and the balance is Fe and impurities;
A martensitic stainless steel material, wherein a ratio D2/D1 of a number density D2 of inclusions at the surface to a number density D1 of inclusions having an equivalent circle diameter of 0.5 to 10 μm in a parent phase at a position at a depth of 1/4 of the thickness from the surface is 0.50 or less, and the number density D2 of the inclusions at the surface is 75 pieces/mm2 or less ^. The martensitic stainless steel material according to claim 4, further comprising, by mass, one or more selected from Ti: 0.001-0.500%, Nb: 0.001-1.000%, V: 0.001-1.000%, W: 0.001-1.000%, Zr: 0.001-1.000%, and Co: 0.001-1.200%. The martensitic stainless steel material according to claim 4 or 5, further comprising, by mass, one or more selected from Ca: 0.0001-0.0100%, B: 0.0001-0.0080%, Sn: 0.001-0.500%, and REM: 0.200% or less. The composition includes, on a mass basis, C: 0.001 to 0.150%, Si: 1.00% or less, Mn: 2.00% or less, P: 0.050% or less, S: 0.0300% or less, Ni: less than 2.00%, Cr: 11.00 to 30.00%, Mo: 6.00% or less, Cu: 0.60% or less, N: 0.050% or less, Al: 0.400% or less, Si+2Al is less than 1.20%, and the balance is Fe and impurities;
A ferritic-martensite duplex stainless steel material, in which a ratio D2/D1 of a number density D2 of inclusions at the surface to a number density D1 of inclusions having an equivalent circle diameter of 0.5 to 10 μm in a parent phase at a position at a depth of 1/4 of the thickness from the surface is 0.50 or less, and the number density D2 of the inclusions at the surface is 75 pieces/mm2 or less ^. The ferritic-martensite duplex stainless steel material according to claim 7, further comprising, by mass, one or more selected from Ti: 0.001-0.500%, Nb: 0.001-1.000%, V: 0.001-1.000%, W: 0.001-1.000%, Zr: 0.001-1.000%, and Co: 0.001-1.200%. The ferritic-martensite duplex stainless steel material according to claim 7 or 8, further comprising, by mass, one or more selected from Ca: 0.0001-0.0100%, B: 0.0001-0.0080%, Sn: 0.001-0.500%, and REM: 0.200% or less. The stainless steel material according to any one of claims 1 to 9, wherein the arithmetic mean roughness Ra of the surface is 0.01 to 0.40 μm. The stainless steel material according to any one of claims 1 to 10, wherein the 60-degree specular gloss Gs (60°) of the surface is 200 to 750%. The stainless steel material according to any one of claims 1 to 11, which has a molten solidified layer on the surface. The stainless steel material according to claim 12, wherein the thickness of the molten solidified layer is 0.50 to 10.00 μm. A method for producing a stainless steel material according to any one of claims 1 to 13,
A descaling process includes irradiating a surface of a cold-rolled steel material with a laser beam to remove oxide scale formed on the surface of the cold-rolled steel material,
The laser beam is irradiated under conditions that allow the region of the cold-rolled steel material to a depth of 0.50 to 10.00 μm from the interface between the parent phase and the oxide scale to be melted. A corrosion-resistant member comprising the stainless steel material according to any one of claims 1 to 13.