JP2000178696A - Ferritic stainless steel excellent in workability and corrosion resistance and production of the thin steel sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain the improvement of the corrosion resistance of the steel as well as the improvement of r-value and the reduction of ridging therein by allowing it to have a specified compsn. contg. C, Sx, Mn, Cr, Al, Mg, N, P, S, Ti, and the balance Fe with inevitable impurities and controlling the area occupancy ratio of nonmetallic inclusions contg. Mg to the value equal to or below the specified one. SOLUTION: This steel has a compsn. contg., by weight, <=0.085% C, <=1.6% Si, <=2.0% Mn, 11 to <=30% Cr, 0.005 to 0.5% Al, 0.0003 to 0.05% Mg, <=0.05% N, <=0.05% P, <=0.03% S, 0.05 to 1.0% Ti, and the balance Fe with inevitable impurities. Then, the area occupancy ratio of nonmetallic inclusions contg. Mg is controlled to <=0.1%. This inclusions contain Mg oxides, but, since this oxides are melted in a neutral-acidic soln. environment, for its prevention, a coating structure by Ti oxides or Ti nitrides is effective. Moreover, preferably, the maximum size of the inclusions is controlled to <=10 μm, and also, the distances between the inclusions are controlled to >=100 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferritic stainless steel having excellent workability and corrosion resistance, and a method for producing a thin steel sheet and a thin steel strip thereof.

[0002]

2. Description of the Related Art Conventionally, ferritic thin steel sheets have been widely used in kitchen appliances and home electric appliances, and in such applications, workability and beauty are required. After roping and press molding, a stripe pattern called ridging is generated, and the reduction in beauty is a major problem.

On the other hand, if an attempt is made to apply a technique for improving workability by rolling a large-diameter roll (having a diameter of 110 mm or more) as disclosed in, for example, Japanese Patent Application Laid-Open No. 4-17615, the concentration of dissolved C and N increases. Since the change in texture after cold rolling annealing did not become the same as that of the low carbon cold rolled steel sheet, no improvement in workability was obtained. It has been difficult to effectively satisfy each requirement of workability and low occurrence of rope and ridging.

[0004]

SUMMARY OF THE INVENTION It has been found that Mg is added to molten steel to refine the structure of a cast slab, and that the r-value can be improved by subjecting a hot-rolled steel sheet to cold working with a large-diameter roll. However, since the Mg-based inclusions are easily dissolved and become rusting points, deterioration of corrosion resistance has been a problem. Then, it made it a subject to propose the stainless steel which improved the r value, reduced the stripe pattern (ridging), and improved the corrosion resistance.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and the gist thereof is as follows. (1) By weight%, C: 0.085% or less, Si: 1.6% or less, Mn: 2.0% or less, Cr: 11 to 30% or less, Al: 0.005 to 0.5%, Mg: 0.0003 to 0.05%, N: 0.05% or less, P: 0.05% or less, S: 0.03% or less, Ti: 0.05 to 1.0%, the balance being A ferritic stainless steel comprising iron and unavoidable impurities, wherein the area occupancy of nonmetallic inclusions containing Mg is 0.1% or less, and is excellent in workability and corrosion resistance. . (2) Further, in terms of% by weight, Ca: 0.0003 to 0.0
A ferritic stainless steel having excellent workability and corrosion resistance according to the above (1), which contains 050%. (3) The ferritic stainless steel according to (1) or (2), further comprising Nb: 0.05 to 1.0% by weight in terms of weight%. (4) Further, by weight%, B: 0.0003 to 0.00
The ferritic stainless steel having excellent workability and corrosion resistance according to the above (1), (2) or (3), containing 5%. (5) Further, by weight%, Ni: 0.05% to 1.0%, Cu: 0.03% to 1.0 %% W: 0.05 to 0.5%, V: 0.05 to 0% 0.5% Zr: 0.05 to 1.0%, Co: 0.005 to 0.5% at least one selected from the group consisting of: (1) to (4). Ferritic stainless steel with excellent workability and corrosion resistance as described. (6) Further, by weight%, Se: 0.005 to 0.5%, Y: 0.005 to 0.5% Sn: 0.005 to 0.05%, La: 0.005 to 0.5% , Ce: 0.005 to 0.5%, Ta: 0.005 to 0.5%, Re: 0.005 to 0.5%, Pd: 0.005 to 0.5%, Ag: 0.005 0.5%, Hf: 0.005 to 0.5%, at least one of the group consisting of: (1) to (5), having excellent workability and corrosion resistance. Excellent ferritic stainless steel. (7) The nonmetallic inclusions contained in the steel include Mg oxide, the Mg oxide is covered with Ti oxide or Ti nitride, and the size of the nonmetallic inclusions is 10
The ferritic stainless steel having excellent workability and corrosion resistance according to any one of the above (1) to (6), wherein the distance between the nonmetallic inclusions is at most 100 μm and the distance is at most 100 μm. (8) By a continuous casting method, a slab containing the component according to any of the above (1) to (6) and having an equiaxed crystal ratio of 50% or more is formed, and the slab is hot-rolled. , Dai径Ro - cold rolling Le, in a weakly oxidizing atmosphere having a dew point of ± 0 ℃ ~-40 ℃ and H ₂ 5% or less balance substantially N _2, eight hundred twenty-five to nine hundred and seventy-five
A method for producing a ferritic stainless steel sheet having excellent workability and corrosion resistance, wherein the steel sheet is subjected to a final pickling after being finally annealed at ℃.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The reasons for limiting the components of the above-mentioned steel sheet will be described below. We believe that the corrosion resistance of the stainless steel sheet according to the present invention is not only the alloying element, but also the occupied area ratio of non-metallic inclusions, as a more accurate index, the size of inclusions, the distribution of inclusions, and the inclusions. Was found to be largely governed by the composition of The details will be described below based on experiments.

The test material was 16% Cr, Mg, Ti, A
A thin steel plate having various contents of l, Ca, C, S, N and O was used, and a cut plate whose surface was wet-polished with an emery polishing paper No. 600 was used. The rust resistance test was performed using artificial seawater spray (35
° C × 4 hours)-Dry (60 ° C × 2 hours)-Wet (RH9
(5% or more × 2 hours) was defined as one cycle, and the evaluation was made in six cycles. The evaluation method used a rating number (SARN) set by the Stainless Steel Association. SARN is correlated with the rust area ratio (the ratio of the area occupied by rust).
ARN = 10 indicates a rust area ratio of 0, and SARN = 0 indicates a rust area rate of 50 to 100%.

[0008] The maximum diameter of inclusions is measured according to JIS G 0
The test surface (15 mm
× 20 mm = 300 mm ² ) was mirror-polished, and the inclusions were individually measured. The diameter of the smallest circle (circumscribed circle of the inclusion) encompassing the entire continuous inclusion was defined as the inclusion diameter, and the maximum value of the inclusion diameter over the entire test surface was defined as the maximum diameter of the inclusion. The distance between inclusions was measured using a mirror-polished surface (15 mm x 2 mm).
The minimum distance among the center distances of the circumscribed circles in the inclusion of 0 mm = 300 mm ² ) was measured. The corrosion resistance was evaluated by a combined cycle corrosion test, which is an accelerated corrosion test simulating a subtropical beach atmospheric environment.

FIG. 1 shows the relationship between the occupied area ratio of nonmetallic inclusions and the rust rating number. As shown in FIG. 1, when the occupied area ratio is 0.1% or less, good corrosion resistance is exhibited. Preferably, if it is 0.02% or less, even better corrosion resistance is exhibited.

FIG. 2 shows the relationship between the maximum diameter of inclusions, the distance between inclusions, and the rust rating number. FIG.
As shown in Table 2, if the maximum diameter of the inclusions is 10 μm or less and the distance between the inclusions is 100 μm or more, good corrosion resistance is exhibited. Preferably, if the maximum diameter of the inclusions is 5 μm or less and the distance between the inclusions is 100 μm or more, even better corrosion resistance is exhibited. More preferably, the maximum diameter of the inclusion is 1 μm.
If it is less than or equal to and the distance between inclusions is 100 μm or more, stable and good corrosion resistance is exhibited.

The reason why the corrosion resistance becomes better as the area occupied by the inclusions becomes smaller as described above is considered as follows. Inclusions appearing on the surface of the steel sheet have a high solubility in acidic to neutral aqueous solutions depending on their composition, and tend to be rusting points. If the inclusion that becomes the rust point is small,
Even if inclusions are dissolved, re-passivation in the pit is easy and local corrosion hardly progresses. And if the distance between the inclusions is small, the corrosion will easily spread due to the connection between the corroded pits,
It is necessary to have a sufficient distance to suppress this.

Although the lower limit of the inclusion occupation area ratio is not particularly defined, the present invention is based on the premise that Mg is added, and thus inclusions are necessarily generated. When Mg is added according to the present invention, the occupied area ratio is usually 0.001%.
That is all.

Further, regarding the composition of inclusions, Mg oxides, Ca oxides and Ca sulfides dissolve in a neutral to acidic solution environment. An oxide or Ti nitride coating structure is effective. Since Ti oxides or Ti nitrides are hardly soluble even in a neutral to acidic solution environment, it is considered that Mg oxides, Ca oxides, and Ca sulfides are prevented from dissolving.

FIG. 3 shows the relationship between the coverage of inclusions containing Mg oxide by Ti oxide or Ti nitride and the cross-sectional melting area ratio of inclusions. Here, the coverage is defined as the portion of the inclusion cross section of the Ti oxide or Ti nitride with the Mg oxide relative to the perimeter of the Mg oxide, that is, the Mg oxide in the inclusion cross section on the test surface of the mirror-polished sample. Was defined as a percentage of the length of the coated part.

[0015] The cross-sectional dissolution area ratio of inclusions was defined by the following formula by comparing the inclusion area by SEM observation and EPMA elemental analysis of the mirror-polished sample exposing the inclusion cross section before and after immersion in the test solution.

The test conditions were 5% NaCl at 50 ° C.
It was immersed in the aqueous solution for 24 hours. The results are shown in FIG. FIG.
As shown in Fig. 5, inclusions are difficult to be unraveled when the coverage is 50% or more. Therefore, the coverage is preferably 50% or more. In order to improve the corrosion resistance, the coverage is more preferably 70% or more, and further preferably 90% or more.

Next, the reasons for limiting the components will be described. C: 0.085% or less C has a small solid solubility limit in ferritic stainless steel and precipitates mainly as Cr carbide, causing intergranular corrosion. However, since a certain amount of C is required from the viewpoint of strength, , 0.085% or less. Preferably, it is good to be 0.01% or less.

Si: 1.6% or less, Si is preferably contained in an amount of 0.1% or more to form a stable SiO ₂ protective film on the steel surface and to improve oxidation resistance. On the other hand, if added in excess, the toughness is reduced and workability is impaired, so the content was made 1.6% or less. Preferably, it is 0.5% or less.

Mn: 2.0% or less Mn is added in an appropriate amount, preferably 0.1% or more, for deoxidation and desulfurization of steel. However, excessive addition of Mn impairs oxidation resistance. 0%.

Cr: 11 to 30% Cr is an indispensable component for ensuring corrosion resistance and high-temperature corrosion resistance. At least 11% is necessary, but if it exceeds 30%, its effect is saturated, and Since the workability and toughness are reduced, the content is limited to 11 to 30%. Preferably, 11 to 25% is good.

Al: 0.005 to 0.5% Al combines with N to form AlN, which is important not only for reducing N in the matrix but for improving toughness and strength, but also as a deoxidizing agent. . However, if the content is less than 0.005%, there is no effect, and if the content exceeds 0.5%, the ridging of the product becomes remarkable. Preferred is 0.01-0.2%.

Mg: 0.0003-0.05% Mg is a component that plays a particularly important role in the present invention. M
g is an element having a higher deoxidizing ability than Ti or Al, and becomes a solidified nucleus of a slab by being finely dispersed as an Mg oxide, whereby the central portion of the slab structure can be made into fine equiaxed crystal grains. In a slab having a fine equiaxed grain structure, recrystallization is promoted during hot rolling, elongation and r-value after cold rolling are improved, and a striped pattern (roping) after cold rolling and a sheet after pressing are performed. Workability and surface properties are improved, such as stripes (ridging) are greatly reduced. However, the Mg oxide remains as inclusions in the steel. Since Mg oxide in inclusions may be dissolved in an acidic solution, it may become a rusting point during use depending on the environment. To prevent rust from Mg oxide,
In order to optimize the amount of added Mg and to suppress the size of inclusions and to prevent the connection of rusting points from expanding, it has been found that a specific dispersion state is effective.
Mg must be contained in an amount of 0.0003% or more to improve workability. However, if it exceeds 0.05%, the corrosion resistance deteriorates, so the upper limit was made 0.05%.

N: 0.05% or less N is a component that improves toughness by reducing solid solution N. Particularly, when the N content exceeds 0.05%, toughness is significantly impaired. Suppress to less than 05%. Preferably, it is 0.02% or less.

P: 0.05% or less P is desirably small from the viewpoint of hot workability, and is preferably 0.0% or less.
Suppress to 5% or less. More preferably, it is good to be 0.03% or less.

S: 0.03% or less S is desirably set to 0.03% or less from the viewpoint of hot workability and corrosion resistance. However, if it is too small, the penetration property during welding is significantly impaired. 0.001% is required. That is, the preferable S content is 0.001 to
0.03% range, more preferably 0.001 to 0.0
2%, more preferably 0.001 to 0.01%, even more preferably 0.001 to 0.01%.

Ti: 0.05 to 1.0% Ti fixes C or N and prevents deterioration of the corrosion resistance of stainless steel. Fix O by coexisting with Mg, Ti, Ca
The generation of oxides of i and Mn is suppressed, and hot workability and corrosion resistance are improved. 0.05% or more and 1.0% or less are added. If it exceeds 1.0%, the hot workability deteriorates.
The upper limit was set to 1.0%.

Ca: 0.0003-0.0050% Ca coexists with Al in low-sulfur steel to fix O, suppress the formation of MnS-based inclusions that can be a starting point of local corrosion, and reduce corrosion resistance. Improve. However, since Ca sulfide and Ca oxide are easily dissolved in an acidic solution, inclusions containing Ca can be a starting point of rust. To prevent rust, like Mg,
In order to reduce the content, suppress the size of inclusions, and prevent the connection of rusting points from expanding, it is effective to set a specific dispersion state. In order to improve the workability, Ca needs to be contained at 0.0003% or more. 0.0
If it exceeds 5%, the corrosion resistance deteriorates, so the upper limit is 0.05%.
And

Nb: 0.05 to 1.0% Nb fixes C or N and prevents deterioration of the corrosion resistance of stainless steel. 0.05% or more to improve corrosion resistance,
1.0% or less is added. If less than 0.05%, there is no effect. If it exceeds 1.0%, hot workability is deteriorated.

B: 0.0003% to 0.005% B increases the grain boundary strength and increases the resistance to cracks during forming, so-called secondary processing cracks. Therefore, the addition of 0.0003% or more is effective. . If the amount is too large, embrittlement cracking occurs during processing, so the upper limit was made 0.005%.

Ni: 0.05 to 1.0% Ni is used together with Cr and other elements in an environment where high corrosion resistance is required. Although it is effective in suppressing local corrosion progress, if it is less than 0.05%, there is no effect, and if it exceeds 1.0%, the effect is saturated, and it is economically expensive.

Cu: 0.03 to 1.0% Cu is an element which improves the corrosion resistance in an acidic environment, being added in the form of a Cr-based component system and further coexisting with Ni and other elements. If it is 0.03% or more, the coexistence effect is remarkable, and if it exceeds 1.0%, the corrosion resistance is saturated and the hot workability is deteriorated.

W: 0.05-0.5% W coexistence effect enhances the corrosion resistance and local corrosion resistance of stainless steel, so 0.5% or less is added as necessary. If it exceeds 0.5%, the effect is saturated. 0.05
There is no effect at less than%.

V: 0.05-0.5% Since the coexistence effect of V improves the corrosion resistance and local corrosion resistance of stainless steel, 0.5% or less is added as necessary. If it exceeds 0.5%, the effect is saturated. 0.05
There is no effect at less than%.

Zr: 0.05-1.0% Since the coexistence effect of Zr improves the corrosion resistance and the local corrosion resistance of stainless steel, 1.0% or less is added as necessary. If it exceeds 1.0%, the effect is saturated. 0.05
There is no effect at less than%.

Co: 0.005 to 0.5% Co coexistence effect improves the corrosion resistance and local corrosion resistance of stainless steel, so 0.5% or less is added as necessary. If it exceeds 0.5%, the effect is saturated. 0.00
There is no effect at less than 5%.

Se: 0.005 to 0.5% Since the coexistence effect of Se improves the corrosion resistance and local corrosion resistance of stainless steel, 0.5% or less is added as necessary. If it exceeds 0.5%, the effect is saturated. 0.00
There is no effect at less than 5%.

Y: 0.005 to 0.5% The coexistence effect of Y improves the corrosion resistance of stainless steel, especially the intergranular corrosion resistance and the pitting corrosion resistance.
% Or less. If it exceeds 0.5%, the effect is saturated. There is no effect if less than 0.005%.

Sn: 0.005 to 0.05% Sn improves the intergranular corrosion resistance, so 0.005 to 0.05% is added as necessary. If added in excess of 0.05%, it can cause cracking during solidification or hot rolling, so the content is 0.05% or less. There is no effect if less than 0.005%.

La: 0.005 to 0.5% The coexistence effect of La improves the corrosion resistance of stainless steel, particularly the intergranular corrosion resistance and the pitting corrosion resistance.
Add 5% or less. If it exceeds 0.5%, the effect is saturated. There is no effect if less than 0.005%.

Ce: 0.005 to 0.5% Ce coexists with Al in low-sulfur steel to fix O, suppress the formation of MnS-based inclusions that can be a starting point of local corrosion, and reduce corrosion resistance. Improve. Add 0.5% or less as needed. If it exceeds 0.5%, the effect is saturated. 0.0
There is no effect at less than 05%.

Ta: 0.005 to 0.5% The coexistence effect of Ta improves the corrosion resistance and local corrosion resistance of stainless steel. Therefore, 0.5% or less is added as necessary. If it exceeds 0.5%, the effect is saturated. 0.00
There is no effect at less than 5%.

Re: 0.005 to 0.5% Re coexistence effect of Re improves the corrosion resistance and local corrosion resistance of stainless steel. Therefore, 0.5% or less is added as necessary. If it exceeds 0.5%, the effect is saturated. 0.00
There is no effect at less than 5%.

Pd: 0.005 to 0.1% The coexistence effect of Pd is a noble metal having a small hydrogen overpotential and promotes passivation of stainless steel and improves corrosion resistance. Add 1% or less. 0.1
If it exceeds%, the effect saturates and is not economical. 0.
If it is less than 005%, there is no effect.

Ag: 0.005 to 0.1% The coexistence effect of Ag is a noble metal, which promotes passivation of stainless steel and improves corrosion resistance. Added. If it exceeds 0.1%, the effect is saturated and is not economical. There is no effect if less than 0.005%.

Hf: 0.005 to 0.5% The coexistence effect of Hf is a carbide forming element and improves the intergranular corrosion resistance of stainless steel.
% Or less. If it exceeds 0.5%, the effect is saturated. There is no effect if less than 0.005%.

The above steel composition and inclusion steel sheet are
By adding Mg, the cross-sectional structure of the slab after continuous casting occupies 50% or more of the equiaxed crystal ratio, and the use of a slab in which inclusions are finely dispersed allows a greater effect to be obtained. In the subsequent steps, a heat treatment such as a hot rolling step or further annealing is performed, followed by cold rolling with a large-diameter roll (having a diameter of 110 mm or more) and annealing. Cold rolling of large diameter rolls improves the rank ford value. The primary purpose of the annealing operation is to soften the cold-rolled and hardened stainless steel sheet, but by controlling the characteristics of the oxide film formed as a result of being exposed to high temperatures, a suitable surface state can be obtained in the subsequent pickling. Securing is also a major goal.

Factors governing the thickness of the oxide film are the annealing plate temperature and the annealing atmosphere. In order to stabilize the structure and the softness, it is necessary to anneal at a temperature higher than the recrystallization temperature based on the steel sheet components. As a result of various experiments to make the oxide film appropriate, when the temperature exceeds 975 ° C, the oxide film becomes too thick at a dew point of ± 0 ° C, and when the dew point is lower than -40 ° C, the oxide film becomes too dense. There is a problem of deteriorating the external appearance and reducing productivity. The plate temperature is 825 ℃
If it is lower, the accumulation of Si in the oxide film for suppressing the formation of the Cr-free layer is insufficient, so that the surface corrosion resistance after pickling deteriorates. Therefore, the annealing temperature was limited to 825 ° C to 975 ° C.

Further, at this annealing plate temperature, an appropriate oxide film thickness is determined.
To secure it, the oxygen concentration in the annealing furnace is detected by the dew point, and ± 0
C. to -40 C. is suitable. The annealing atmosphere gas is H_Two
And N _TwoUse a mixed gas of H_TwoToo much
The strength is so strong that a sufficient oxide film is not formed,_TwoIs expensive
It is not economical. Therefore, the annealing atmosphere gas has the composition
Is H_TwoLess than 5%, the balance is substantially N_TwoUse those.
Especially when the gas composition is H_Two3 to 5% at the balance substantially N_TwoIn
If combined with the above dew point and a more moderately weak oxidizing atmosphere
It is desirable.

In the subsequent pickling, the primary purpose is to remove the oxide film, but the exposed Mg oxide, C
Since most of the oxides and Ca sulfides are removed, the corrosion resistance is unfailingly exhibited especially in the pickling solution containing nitrate ions (NO ³⁻ ) in combination with the strengthening of the passive film.

[0050]

[Example 1] The steel of the present invention and the comparative steel shown in Table 1 had a diameter of 500 mm after melting, heating and hot rolling.
Table 3 shows the results of evaluation of corrosion resistance and workability after soft rolling and pickling under the conditions shown in Table 2. The corrosion resistance evaluation method is the same as described in the text. The method of the present invention is excellent in both corrosion resistance and workability.

[0051]

[Table 1]

[0052]

[Table 2]

[0053]

[Table 3]

[0054]

As described above, the ferritic stainless steel obtained from the present invention is excellent in workability and corrosion resistance, and requires workability, corrosion resistance, and beautiful surface of electric appliances, gas appliances, kitchen appliances and the like. It can be used as a material for equipment to be used.

[Brief description of figures]

FIG. 1 is a diagram showing a range of a preferable area occupation ratio of nonmetallic inclusions from the viewpoint of rust rating number (SARN).

FIG. 2 is a view showing a preferred range of the maximum diameter of inclusions and the distance between inclusions from the viewpoint of rust rating number (SARN).

FIG. 3 is a view showing a range of a coverage of Mg oxide with Ti oxide or Ti nitride, which is effective for preventing inclusion from being dissolved.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22C 38/60 C22C 38/60 (72) Inventor Masayuki Abe 1-1 New Toba-cho, Tobata-ku, Kitakyushu-shi, Fukuoka Nippon Steel Corporation Yawata Works (72) Inventor Masamitsu Tsukunaga 1-1 Niwahata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka Prefecture Nippon Steel Corporation Yawata Works (72) Inventor Ken Kimura Futtsu, Chiba Prefecture 20-1 Ichi Shintomi Nippon Steel Corporation Technology Development Division F-term (reference) 4K032 AA00 AA01 AA02 AA04 AA08 AA09 AA13 AA14 AA16 AA21 AA22 AA23 AA27 AA29 AA30 AA31 AA32 AA33 AA35 AA36 AA37 CHA4A04 EA02 EA05 EA09 EA10 EA12 EA13 EA15 EA18 EA19 EA20 EA23 EA25 EA27 EA28 EA29 EA31 EA32 EA33 EA35 EB06 EB07 EB08 EB09 EB13 EC04 EC05 FH01 FJ02 FJ05 FJ06 HA06 JA04 JA06

Claims (8)

[Claims] 1. In weight%, C: 0.085% or less, Si: 1.6% or less, Mn: 2.0% or less, Cr: 11 to 30% or less, Al: 0.005 to 0.5 %, Mg: 0.0003 to 0.05%, N: 0.05% or less, P: 0.05% or less, S: 0.03% or less, Ti: 0.05 to 1.0% Ferritic stainless steel comprising a balance of iron and unavoidable impurities, wherein the area occupancy of non-metallic inclusions containing Mg is 0.1% or less, and is excellent in workability and corrosion resistance. Stainless steel. 2. The composition according to claim 1, further comprising:
The ferritic stainless steel having excellent workability and corrosion resistance according to claim 1, which contains 0.0050%. 3. Nb: 0.05-1.
The ferritic stainless steel having excellent workability and corrosion resistance according to claim 1 or 2, which contains 0%. 4. B: 0.0003-% by weight
3. The composition according to claim 1, further comprising 0.005%.
Or a ferritic stainless steel excellent in workability and corrosion resistance according to 3. 5. Ni: 0.05% to 1.0% Cu: 0.03% to 1.0% W: 0.05 to 0.5% V: 0.05 to 5% by weight The processing according to claim 1, 2, 3 or 4, wherein at least one kind is contained from the group of 0.5% Zr: 0.05 to 1.0% Co: 0.005 to 0.5%. Ferritic stainless steel with excellent resistance and corrosion resistance. 6. Further, in weight%, Se: 0.005 to 0.5% Y: 0.005 to 0.5% Sn: 0.005 to 0.05% La: 0.005 to 0.5% Ce: 0.005 to 0.5% Ta: 0.005 to 0.5% Re: 0.005 to 0.5% Pd: 0.005 to 0.5% Ag: 0.005 to 0.5% The ferritic stainless steel having excellent workability and corrosion resistance according to claim 1, 2, 3, 4, or 5 containing at least one member from the group of Hf: 0.005 to 0.5%. 7. The non-metallic inclusions contained in steel include Mg oxide, the Mg oxide is covered with Ti oxide or Ti nitride, and the size of the non-metallic inclusions is 10 μm. Below, the distance between non-metallic inclusions is 100 μm
Claims 1, 2, 3, 4, 5
Or a ferritic stainless steel excellent in workability and corrosion resistance according to 6. 8. A slab containing the component according to any one of claims 1 to 6 and having an equiaxed crystal ratio of 50% or more by a continuous casting method, and the slab is hot-rolled. Later, large diameter ro
At a dew point of ± 0 ° C. to −40 ° C. and H _{2 of} 5% or less in a substantially oxidizing atmosphere of N _2.
A method for producing a ferritic stainless steel sheet having excellent workability and corrosion resistance, which is characterized by applying a pickling finish after final annealing at 75 ° C.