JPH02270942A - High-purity and high-cleanliness stainless steel excellent in crevice corrosion resistance and rust resistance and its production - Google Patents

Abstract

PURPOSE:To obtain a high-purity and high-cleanliness stainless steel excellent in crevice corrosion resistance and rust resistance by subjecting a molten steel which has a prescribed composition and in which cleanliness consisting of the sum of oxide-type inclusions and sulfide-type inclusions is regulated to a specific value or below to continuous casting under the prescribed temp. conditions and then to hot rolling. CONSTITUTION:A molten steel which has a composition containing, by weight, 0.01-0.1% C, <=3% Si, <=2% Mn, 14-26% Cr, 0.005-0.2% N, <=0.02% P, <0.001% S, 0.02-0.2% Al, <0.003% O, further one or more kinds among <=3% Mo, <=2% Cu, and <=2% Ni, and <=0.01% B and in which cleanliness consisting of the sum of oxide-type inclusions and sulfide-type inclusions is regulated to <=0.02% is continuously cast under the temp. condition in which T is regulated to <=45 deg.C, and the resulting cast slab is heated to or held at <=1230 deg.C, followed by hot rolling. By this method, an inexpensive ferritic stainless steel having superior workability as well as the above properties can be obtained.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a high-purity, high-clean ferritic stainless steel that has excellent corrosion resistance, particularly crevice corrosion resistance, rust resistance, and excellent workability. The present invention relates to a method of manufacturing at low cost.

(Conventional technology) Ferritic stainless steel, mainly 17% Cr steel, is
Conventionally, it has been widely used mainly as a thin plate due to its low cost, but 18%Cr-8%Ni1
It is considerably inferior in corrosion resistance and workability compared to austenitic stainless steels such as 1.

In particular, in terms of corrosion resistance, even when used under relatively mild conditions such as in the atmosphere, naturally occurring water, tap water, or hot water, welded and processed parts easily rust. In addition, there are also problems with corrosion resistance in the base metal. In order to expand the uses of ferritic stainless steel, it is required to significantly improve its corrosion resistance. In addition, in terms of workability, it is necessary to improve the drawability and stretchability.

In the past, many studies have been conducted to improve the corrosion resistance and workability of ferritic stainless steel, and as a result, the properties have been improved mainly by adding alloys.

Regarding corrosion resistance, the degree of corrosion resistance required varies depending on the usage environment, and it is not possible to set a standard for it. Therefore, selective addition of Mo, CuSNi, Ti, Nb, etc. depending on the purpose is known and has been put into practical use.

On the other hand, regarding improvement of workability, 7i, 33. Addition of Al, reduction of C and N, hot rolling conditions, heat treatment conditions, and combinations thereof have been investigated.

However, when the conventional technology improves the properties of steel by adding alloys, it not only increases the manufacturing cost, but also obstructs the simplification of the manufacturing process and lengthens the manufacturing time, which also increases the manufacturing cost.

(Problems to be Solved by the Invention) In order to solve the problems in the conventional technology, the present invention utilizes high-purity, high-cleanliness steel refining technology to produce an inexpensive ferritic stainless steel with excellent corrosion resistance and excellent workability. The purpose was to provide steel and methods for making and using it.

(Means for solving problems) The gist of the present invention is as follows.

(1) C: 0.01 to 0.1% by weight, Si: 3% or less, Mn: 2% or less, Cr: 14 to 26%, N: 0
．． 005-~0.2%, P: 0.02% or less, S
: less than 0.001%, Al: 0.02-0.2%
, O: less than 0.003%, Mo: 3% or less, Cu
: 2% or less, Ni: 2% or less, the remainder substantially consists of Fe, and the cleanliness of the sum of oxide inclusions and sulfide inclusions is 0.02 or less High purity with excellent crevice corrosion resistance and rust resistance,
Highly clean stainless steel.

(2) C: 0°01 to 0.1% by weight, Si: 3% or less, Mn: 2% or less, Cr: 14 to 26%, N:
0.005-0.2%, P: 0.02% or less, s
: o, o o less than i%, A! : 0.02~0
．． 2%, O: less than 0.003%, MO: 3% or less, Cu: 2% or less, Ni: 2% or less, Ti: 0.6% or less, V: 0.02 ~0.5%,
Nb: Contains 0.02 to 0.2% of one or more types, the remainder substantially consists of Fe, and the cleanliness consisting of the sum of oxide inclusions and sulfide inclusions is 0.02 or less High purity, high purity stainless steel with excellent crevice corrosion resistance and rust resistance.

(3) C: 0.01-0.1%, Si: 3 in weight%
% or less, Mn: 2% or less, Cr: 14-26%, N
: 0.005-0.2%, P: 0.02% or less, S:O, less than 001%, Al: 0.02-0.2
%, O: less than 0.003%, further Mo: 3% or less,
Contains one or more of Cu: 2% or less, Ni: 2% or less, and B: 0.01% or less, with the remainder substantially consisting of Fe, and oxide inclusions and sulfide inclusions. A high-purity, high-cleanliness stainless steel with excellent crevice corrosion resistance and rust resistance, characterized by a cleanliness of 0.02 or less.

(4) C: 0.01-0.1%, Si: 3% or less, Mn: 2% or less, Cr: 14-26%, N:
0.005-0.2%, P: 0.02% or less, 10.
Less than 0.001%, A7: 0.02-0.2%, O:
Less than 0.003%, further Mo: 3% or less, Cu: 2%
Below, Ni: 2% or less of one or more types, Ti: 0
．． 6% or less, V: 0.02-0.5%, Nb: 0102
~0.2% of one or more types, and B: 0.01
% or less, the remainder substantially consisting of Fe, and the cleanliness consisting of the sum of oxide inclusions and sulfide inclusions is 0.02 or less, and has crevice corrosion resistance and rust resistance. Excellent high-purity, high-cleanliness stainless steel.

(5) C: 0.01 to 0.1% by weight, Si: 3% or less, Mn: 2% or less, Cr: 14 to 26%, N: 0
．． 005-0.2%, P: 0.02% or less, S;
Less than 0.001%, A! : 0.02~0.2%, O
n less than 0.003%, Mo: 3% or less, Cu:
2% or less, Nj: Contains one or more of 2% or less, the remainder substantially consists of Fe, and the cleanliness consisting of the sum of oxide inclusions and sulfide inclusions is 0.02 or less. A method of continuous casting of a certain molten steel under a casting temperature condition of ΔT≦45°C, heating or holding the obtained slab to a temperature not exceeding 1230°C, and then hot rolling. A method for manufacturing high-purity, high-cleanliness stainless steel with excellent crevice corrosion and rust resistance.

Here, ΔT=(temperature of molten steel in tundish during continuous casting in °C)-(solidification temperature of molten steel in °C) Below, the present invention will be described in detail.

The present inventors focused on steel refining technology, especially high purification refining technology that can extremely reduce the content of S, P, 0, etc., and by minimizing the amount of alloy added, the corrosion resistance of ferritic stainless steel was improved. , much research has been conducted with the aim of improving workability and simplifying the manufacturing process.

As a result, the high purification refining technology that can reduce S, P, and 0 in ferritic stainless steel and further reduce oxide inclusions and sulfide inclusions to extremely low levels meets the above objectives. They discovered this and completed the present invention.

In order to obtain high-grade ferritic stainless steel, advances are being made in technology to reduce the impurities C and N.
Although stainless steel with a carbon content of about 0.01% has been put into practical use, the present inventors have not fully clarified the roles of C and H and have studied the composition system in order to effectively utilize them. This point is a feature of the present invention.

High-purity refining technology uses CaC2fCaFz-based flux, etc., to blow into molten steel to reduce S≦ even in stainless steel.
This is a technology that makes it possible to achieve P 10 ppm and P≦200 ppm at low cost, and furthermore, reductions in C and N have already been achieved on an industrial scale.

The present inventors focused on these high purification refining technologies, and
Although we considered the manufacturing process, 17%Cr
As a result of an electrochemical study of the corrosion resistance, particularly the rusting resistance, of ferritic stainless steels, it was found that reducing P is extremely effective in increasing the resistance to passive state destruction caused by CI-. On the other hand, when S is reduced, 17
It was found that the passivation properties of %Cr-based ferritic stainless steel were significantly improved, and furthermore, due to the synergistic effect with the reduction of P, the resistance to passivity destruction due to CI- could be significantly improved.

Furthermore, with the low S bait, by deoxidizing the molten steel with M or Tt, etc., sulfide-based inclusions and oxide-based inclusions can be easily floated, and steel with extremely high purity can be obtained.

It has been revealed that the ferritic stainless steel thus obtained has improved overall corrosion resistance, crevice corrosion resistance, and bendability.

The experimental facts from which we obtained the accumulated technical knowledge are described below.

The present inventors have melted alloys focusing on 17% Cr ferritic stainless steel in a vacuum melting furnace with a focus on low 0, low P, and low S. The corrosion resistance and workability of the product were investigated by taking rolling conditions, hot-rolled plate annealing conditions, cold rolling conditions, final annealing conditions, etc. into consideration. The product board thickness is 0.7M.

Regarding corrosion resistance, the obtained products were subjected to various immersion tests as well as electrochemical measurements. As a result, it became clear that the influence of process conditions on corrosion resistance was not significant, but that the influence of alloy composition was significant.

In particular, as shown in Figure 1, P is 200 ppm or less, S
It has been found that the passivation properties of this type of alloy as well as the resistance to passivation breakdown due to CI'' can be significantly improved by reducing the amount of C1 to less than 10 ppm.

In Fig. 1 (a): In the steel of curve 1, P: 50 ppm,
S: in steel with sppm curve 2, P: 30 ppm,
S: 9ppm in steel of curve 3, P: 50ppm
, S: 60ppm in steel of curve 4, P: 50ppm
, S: 140 ppm Figure 1 (b): In steel of curve 1,
P: 50ppm, S: 8ppm in the steel of curve 2, P: 1100pp, S: 8ppm in the steel of curve 3, P: 150ppm, S: 8ppm in the steel of curve 4, P: 250ppm, S: 8ppm in the steel of curve 5
In the steel, P: 340 ppm, S: 8 ppm, and S is 10 ppm or more in Fig. 1 (a), curve 3.4,
From the results of curve 4.5 (first run) where P is 200 ppm or more, it can be seen that the passive breakdown potential (V) due to 01'' is on the negative side, and the passive properties are poor.

These results are noticeable in the crevice corrosion test, and as shown in FIG. 2, remarkable effects are exhibited when S: less than 10 ppm and P: less than 200 ppm.

Figure 2 shows the effect of lowering S and lowering P in a crevice corrosion test between 17% Cr stainless steel sheets.The test conditions were 600 ppm Cl-110p.
pm Cu'', 80°C for 14 days, with air blowing, and the average depth of five deep locations within the gap is plotted as the maximum crevice corrosion depth (mm).

It can be seen that at P: 300 ppm, crevice corrosion is deep even when S is less than xoppm.

As S is reduced, the number of nonmetallic inclusions in the steel decreases significantly, and A-based inclusions (sulfide-based, sulfide-earth oxide-based inclusions, thing)
is no longer observed, and by combining deoxidation with M and/or Ti, etc., B-based and C-based inclusions (all oxide-based inclusions) become easier to float, and O in the steel becomes lower. The steel material has a cleanliness level of 0.02 or less with extremely few nonmetallic inclusions.

The cleanliness was measured according to JIS. Corresponding to this behavior, the pitting potential in 3.5% NaCl solution is also significantly responsible.

Figure 3 illustrates the accumulation phenomenon, and shows the effects of inclusion cleanliness (bottom diagram in Figure 3) and pitting corrosion potential (top diagram in Figure 3) due to the low S content of 17% Cr stainless steel. It shows change.

The lower diagram in Figure 3 shows a 50kg sample of 17% Cr stainless steel.
! It shows the relationship between S of Fjl mass and inclusion cleanliness, and A
The dotted line represents the total cleanliness of system inclusions (marked with *) and B and C system inclusions (marked). Also, the upper part of Figure 3 shows 17%
It shows the relationship between pitting dislocation (V) and S measured on a 4600 polished surface of a Cr stainless steel product plate, S: 10pp
It can be seen that it becomes significantly more noble below m.

FIG. 4 shows the influence of S, P, and 0 on the rusting resistance of 17% Cr stainless steel. It can be seen that when O is less than 30 ppm, P: 200 ppm or less, S: 1101) or less, and the cleanliness is set to 0.02 or less, the rusting rank increases rapidly.

In other words, this high-purity, high-cleanliness ferritic stainless steel has improved basic corrosion resistance such as active dissolution behavior, pitting corrosion resistance, and crevice corrosion resistance, and has been tested in an improved salt water test that simulates rusting in the atmosphere. Make the result good. Note that FIG. 4 shows the results of an improved salt water test using a 30°C solution of 0.5% NaCl + 0.2% H20□.

Significant improvement in corrosion resistance is further ensured by the above-mentioned high purity and high cleanliness, and addition of small amounts of various elements effective for corrosion resistance. The present inventors envisioned various uses for Cr, , Ni.
, Mo, CuSTi, AU, Nb, Si, V
We investigated the effects of adding elements such as C and N, and also investigated the effective use of C and N as additive elements.

As an accelerated test in a near-neutral corrosive environment, 4% Na
An immersion test was conducted with CZ + 0.2% H20, at 60°C. From these results, the amount of Cr (Fig. 5), Mo
It has been found that the effects of addition of , Cu, old, ■, Ti, etc. (Fig. 6) are more pronounced in low S, low P, and low O alloys. In this way, highly purified steel with low P, low S, and low O shows effects on corrosion resistance by itself, but the effect of adding alloying elements such as Mo, Cu, and Ni becomes even more pronounced, and these expensive alloying elements are It has become clear for the first time that the amount added can be reduced.

Regarding the requirements regarding the workability of ferritic stainless steel products, we investigated bendability, bendability after cold working, and depending on the application, deep drawability and ridged properties during drawing. First, regarding bendability, the influence of process conditions is small, but the influence of alloy composition is large. In particular, cracks occurred due to the alloy in a processing 0 bending test in which the product sheet was subjected to about 30% cold working and then tightly bent in a direction perpendicular to the rolling direction. Obviously, S:0.
Less than 0.001% (10 ppm), O: 0.003% (
30ppm) and P: 0.02% (200p
In the alloys below (pm), no cracks occurred at all in a processing zero bending test in which tight bending was performed in a direction perpendicular to the rolling direction.

The deep drawing characteristics of ferritic stainless steel products were evaluated by determining the r value. Specified tensile test pieces were taken from the product plate in the rolling direction, in a direction perpendicular to the rolling direction, and in a 45° direction to the rolling direction, respectively, and the r value was measured.

Further, after applying a 20% tensile strain to a specified tensile test piece in the rolling direction, the height of the generated odging was measured using a roughness meter.

It is well known that not only the alloy composition but also the hot rolling conditions and subsequent heat treatment have a large influence on the ridges and r value of a ferritic stainless steel sheet. Hot-rolled plate annealing has a particularly large influence on high-cleanliness steel.
We investigated the effects on ridges and r-values when using a continuous annealing method that rapidly heats the IJ tube, when using a conventional bell-type annealing furnace, and when hot-rolled plate annealing is omitted. .

As a result, the results were basically the same as the conventional findings,
It has become clear that C and N are effective when used in appropriate amounts. Thus, it has been found that even in high-purity, high-cleanliness steel, the alloy composition, hot rolling conditions, and hot-rolled sheet annealing have an effect on ridging and r-value.

In order to obtain a product with excellent deep drawing characteristics, it is necessary to add A/Ti and take advantage of the effects of hot-rolled plate annealing.

In addition, for high-purity, high-cleanliness steel, it has been found that grain refinement during casting and optimization of the material heating temperature during hot rolling are important control points for product ridging and r-value. . This is because in high-purity alloys, grains tend to grow easily and become coarse. That is, in high-purity, high-cleanliness steel, in order to refine the casting structure, the degree of superheating ΔT (°C) of molten steel during casting (ΔT = molten steel temperature at tundish - solidification temperature of molten steel (calculated value))
needs to be made smaller. Specifically, ΔT (°C)≦4
5°C is required. On the other hand, the material heating temperature during hot rolling needs to be 1230''C or less from the viewpoint of preventing grain coarsening.

As mentioned above, based on advanced refining technology that can significantly reduce P and S, which are impurities harmful to product properties, by using CaC-based fluxes, we have further reduced 0. By increasing the purity and cleanliness of the product, we were able to improve the passivation ability of the product and provide it with excellent corrosion resistance. Furthermore, by increasing purity and cleanliness, the effect of adding elements such as Mo, Ca, and Ni can be made significant, and the amount added can be reduced. Furthermore, by reducing S and O, the steel can sufficiently withstand severe bending.

In high-purity, high-cleanliness ferritic stainless steel with low P, low S, and low O, the effect of adding AJSTi to improve the workability of thin sheet products is remarkable, and the addition of appropriate amounts of C and H is effective. In addition to the above effects, it has become clear that addition of a small amount brings about a significant property improvement effect.

Next, the reason for limiting the components of the high-purity, high-cleanliness ferritic stainless steel of the present invention will be explained.

CTC is effective in improving corrosion resistance and workability in low P, low S, and low O steel, and from this point of view, CTC is 0.01
Add in a range of ~0.1%. If it is less than 0.01%, the processability of the product will deteriorate, and if it is added in excess of 0.1%, the corrosion resistance of the product will be impaired.

Si: Si slightly improves corrosion resistance in low P, low S1, and low O steel, but does not affect workability.

When added in excess of 3%, it hardens the steel. Therefore, 3
% or less.

Mn: A low Mn content is desirable for the corrosion resistance of steel, and from this point of view it was set to 2.0% or less.

Cr: Cr is an essential element for ferritic stainless steel, and addition of 14 to 26% significantly improves corrosion resistance. If it is less than 14%, the effect of addition is insufficient, and if it is added in excess of 26%, processability deteriorates.

N: N improves the corrosion resistance of high-purity, high-cleanliness ferritic stainless steel. However, from the viewpoint of steel workability, it is desirable that the amount added be 0.2% or less. Therefore,
The content was set at 0.005 to 0.2%.

Since FDP impairs the passive properties of ferritic stainless steel, particularly the resistance properties against passive breakdown due to 01-, the content thereof should be as low as possible. From this point of view, the content must be 0.02% (200 ppm) or less.

Since SO3 impairs the passive properties of ferritic stainless steel, it is preferable that its content be as low as possible. From this point of view, it should be less than 0.001%.

A1:A! In ferritic stainless steel with low P, low S, and low O, a content of 0.02 to 0.2% significantly improves the 7 value of the product and improves the cleanliness of the steel. . If the amount added is less than 0.02%, the addition effect will be insufficient, and if it is added in excess of 0.2%, the ridging properties of the product will deteriorate.

If the S content is less than 0.001% (1.0 ppm), oxide inclusions will be formed in the steel, which will deteriorate the rust resistance and pitting corrosion resistance of the product, so the content should be kept as low as possible. It is desirable that the value be as low as possible. Therefore, 0.003% (30pp
m). S: In steel with less than 0.001%, sulfides are eliminated and oxides have good floating properties.

Mo, Cu, Ni: Mo, Cu, Ni are
In high-purity, high-cleanliness ferritic stainless steel with low P, low S, and low 0, the corrosion resistance of the steel is significantly improved by adding a small amount. However, Mo, Cu,
The effect of Ni is saturated at 3%, 2%, and 2%, respectively, and adding amounts exceeding these values is disadvantageous in terms of cost.

Ti, Nb, V: Tf, Nb, and V are carbonitride-forming elements, and are each 0.6% or less in low P1, low S1, low O, high purity, high cleanliness ferritic stainless steel. 0.02-0.2%, 0.02-0
．． The addition of 5% causes the precipitation of fine carbonitrides, thereby improving the corrosion resistance of the steel. In particular, Ti also improves processability and further improves cleanliness.

BIB improves the workability of low-P, low-S, high-purity, high-cleanliness ferritic stainless steel by adding a small amount. From this point of view, it is added in an amount of 0.01% or less. Addition of more than 0.01% deteriorates the corrosion resistance of steel.

Regarding the cleanliness of steel: Sulfide-based or oxide-based nonmetallic inclusions become a starting point for pitting corrosion and accelerate corrosion in product applications. Furthermore, it is desirable that the cleanliness is as low as possible (clean) since it deteriorates the bendability.

After melting low S ferritic stainless steel, M
It is necessary to make the cleanliness of the hot-rolled sheet 0.02 or less by deoxidizing with or Tj and allowing time for the oxide to float.

Superheating degree of molten steel during casting ΔTC℃): The casting temperature of molten steel is
For low S, low P, and low 0 steel, ΔT (℃)≦4
It needs to be 5°C. If ΔT (°C) exceeds 45°C, the grains tend to become coarse, making it impossible to obtain a product with desired processability.

(Example) High-purity stainless steel alloy is melted using pre-treated hot metal, Fe-Cr alloy is added and melted in a 150T converter, and the steel is tapped with a C level of about 0.2%. Then, in a ladle, Ca
Blow Cz-based flux, P less than 0.015%,
After reducing the S content to less than 0.001%, final decarburization was performed in a VOD furnace. After that, it was further desulfurized with desulfurization flux, deoxidized by blowing M or Ti to float the inclusions, and then continuously cast into a 200mm thick CC slab, and some of it was made into an ingot. In the case of continuous casting, the casting conditions were such that ΔT≦45°C was satisfied and the slab was made. The ingot was bloomed into a slab. The hot rolling heating temperature of this slab is 1100
℃, and the hot rolling conditions were low temperature rolling in which the finishing rolling start temperature was controlled to 900° C. or lower, and a hot coil having a thickness of 3 ym was used.

Thereafter, hot-rolled plate annealing consisting of rapid heating to 1000° C. was performed by continuous annealing, followed by continuous pickling. All the cold rolling was carried out once to a thickness of 0.7 tm, followed by final annealing at 850° C. and pickling to obtain a product sheet. As a comparison material, a thin stainless steel plate manufactured under normal conditions was used.

The results of the obtained products are shown in Table 1.

The steel of the present invention has all S content due to CaCz-based high purification treatment.
: Less than 0.001%, P: 0.02% or less, 0:
It satisfies less than 0.003%. Furthermore, the inclusion cleanliness measured on hot-rolled sheets is also extremely excellent. The characteristics test results of these products are shown in Table 2 and show their corrosion resistance properties.

Excellent performance in use, especially in terms of workability, was obtained, confirming the effectiveness of the present invention.

As described above, the steel of the present invention was obtained by clarifying the effects of high purification and high cleanliness of the alloy on the usage properties, mainly corrosion resistance, which is a basic property, and by combining it with a small amount of effective additive elements. Furthermore, the manufacturing method requires regulating the casting conditions and heating temperature conditions of the slab during continuous casting, but manufacturing conditions other than those of the present invention, such as continuous casting and hot rolling, are also applicable. Directly connected CC-DR
It is clear that the basic properties of the steel of the present invention remain unchanged even if it is produced by the process or the CC-hot charge process, and it will still exhibit the desired properties. It also shows excellent properties in products such as bright annealing.

[Brief explanation of drawings]

Figure 1 a and b show a solution containing CI- of 17% Cr stainless steel (3% Na1J + 5% Hz SOa, 30°C, Ar
Figure 2 shows the effects of low S and low P on the crevice corrosion test that occurs between 17% Cr stainless steel sheets.
Figure 3 shows changes in inclusion cleanliness and pitting potential due to low S content in 17% Cr stainless steel;
A diagram showing the influence of S, P, and 0 on the rusting resistance of Cr-based stainless steel.
Figure 6 shows the effects of Cr1l and high purity alloys on corrosion resistance at +0.2%tbOz, 60°C.
7% Cr stainless steel (C0.03%, NO.01%
) Corrosion rates of practical alloys and high-purity alloys against the effects of various additive elements (4%Na1J + 0.2%H, 02, 60''
It is a figure showing the difference in C). In Figure 6, 2-co practical alloys (Po, 03%, SO, 005%, OO, 00
5%) Niniko high purity alloy (PO, 014%, SO, 0007%, OO,
0018%) Electricity Ω V (S, C, E)
t4α V (S, C,
E) Figure 4 ppm Figure 6 Procedural amendment (voluntary) October 9, 1999 Director General of the Japan Patent Office Yoshi 1) Takeshi Moon 1, Display of the case 1999 Patent Application No. 233030 2, Name of the invention High-purity, high-purity stainless steel with excellent corrosion and induction resistance and its manufacturing method 3, and its relationship to the amended case Patent applicant: 6-3 Otemachi 2-chome, Chiyoda-ku, Tokyo (665) Nippon Steel Corporation Kurasha Co., Ltd. Representative Yutaka Saito 4, Agent 〒io. 6. Column 7 for detailed description of the invention in the specification to be amended, Contents of the amendment

Claims (5)

[Claims] (1) In weight%, C: 0.01-0.1%, Si: 3% or less, Mn: 2% or less, Cr: 14-26%, N: 0.0
05-0.2%, P: 0.02% or less, S: 0.001
%, N: 0.02 to 0.2%, O: less than 0.003%, Mo: 3% or less, Cu: 2% or less, Ni: 2
% or less, and the remainder is substantially Fe.
A high-purity, high-clean stainless steel with excellent crevice corrosion resistance and rust resistance, characterized by a cleanliness level of 0.02 or less, which is the sum of oxide inclusions and sulfide inclusions. . (2) In weight%, C: 0.01-0.1%, Si: 3% or less, Mn: 2% or less, Cr: 14-26%, N: 0.0
05-0.2%, P: 0.02% or less, S: 0.001
%, N: 0.02 to 0.2%, O: less than 0.003%, Mo: 3% or less, Cu: 2% or less, Ni: 2
% or less, Ti: 0.6% or less, V
: 0.02-0.5%, Nb: 0.02-0.2% 1
containing one or more species, the remainder substantially consisting of Fe,
A high-purity, high-clean stainless steel with excellent crevice corrosion resistance and rust resistance, characterized in that its cleanliness, which is the sum of oxide-based inclusions and sulfide-based inclusions, is 0.02 or less. (3) In weight%, C: 0.01-0.1%, Si: 3% or less, Mn: 2% or less, Cr: 14-26%, N: 0.0
05-0.2%, P: 0.02% or less, S: 0.001
%, Al: 0.02-0.2%, O: 0.003%
Mo: 3% or less, Cu: 2% or less, Ni:
2% or less of one or more types, and B: 0.01%
It has crevice corrosion resistance and rust resistance characterized by containing the following, the remainder being substantially Fe, and having a cleanliness of 0.02 or less, which is the sum of oxide inclusions and sulfide inclusions. Excellent high-purity, high-cleanliness stainless steel. (4) C: 0.01 to 0.1% by weight, Si: 3% or less, Mn: 2% or less, Cr: 14 to 26%, N: 0.0
05-0.2%, P: 0.02% or less, S: 0.001
%, M: 0.02 to 0.2%, O: less than 0.003%, Mo: 3% or less, Cu: 2% or less, Ni: 2
% or less, Ti: 0.6% or less, V
: 0.02-0.5%, Nb: 0.02-0.2% 1
species or two or more species, and B: 0.01% or less,
High purity with excellent crevice corrosion resistance and rust resistance, characterized by a cleanliness of 0.02 or less consisting of the sum of oxide inclusions and sulfide inclusions, with the remainder essentially consisting of Fe. , high clean stainless steel. (5) In weight%, C: 0.01-0.1%, Si: 3% or less, Mn: 2% or less, Cr: 14-26%, N: 0.0
05-0.2%, P: 0.02% or less, S: 0.001
%, Al: 0.02-0.2%, O: 0.003%
Mo: 3% or less, Cu: 2% or less, Ni:
Contains 2% or less of one or more species, the remainder being substantially F
molten steel with a cleanliness of 0.02 or less, which is the sum of oxide inclusions and sulfide inclusions, at ΔT≦45°C.
Continuous casting was carried out under casting temperature conditions of 123
A method for producing high-purity, high-cleanliness stainless steel with excellent crevice corrosion resistance and rust resistance, which comprises heating or holding at a temperature not exceeding 0°C and then hot rolling. Here, ΔT = (molten steel temperature in tundish during continuous casting in °C) - (solidification temperature of molten steel in °C)