JPS59226150A - Ferritic stainless steel with superior workability and corrosion resistance - Google Patents

Abstract

PURPOSE:To improve the workability and corrosion resistance by adding prescribed percentages of C, Si, Mn, P, S, Cr, Al, N and O to Fe. CONSTITUTION:The titled stainless steel consists of, by weight, <=0.07% C, <=30% Si, 0.03-5% Mn, <=0.02% P, <=0.001% S, 9-15% Cr, <=0.2% Al, <=0.15% N, <=0.003% O and the balance Fe. The amounts of Cr, C and N in the composition are set in the obliquely lines part defined by straight lines connecting points (a), (b), (c), (d) in the diagram. The stainless steel is inexpensive and has superior workability and corrosion resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ferritic stainless steel that is mainly made of thin stainless steel sheets and has excellent workability and corrosion resistance, and is inexpensive.

Traditionally, in the field of stainless steel thin plates, SUS
304 ('18% Cr -8% Ni Lun), SU
S 430 (17% Cr steel) has been used. However, these steels are very expensive because they contain a large amount of Cr or Ni. Also, SUS 430 is SUS 3
Although it is cheaper than 04, it has the disadvantage of inferior workability and corrosion resistance.

On the other hand, looking at the recent trend in demand for 1trO, demand for stainless steel sheets is expected to increase as living standards become more sophisticated and uses expand.
There is now a demand for an inexpensive gas stainless steel that has workability and corrosion resistance equivalent to or better than US 430.

SUS is a conventionally used inexpensive stainless steel forging.
410. Examples include Al5I 409. Recently, these have been made with low C and low N, and alloys have been added to improve workability.
Weldability has been improved, but corrosion resistance is still SU
It's inferior to S430. On the other hand, with recent advances in refining technology, it has become possible to achieve low P and S at a relatively low cost.
Research into high purification has become active. However, studies on high purity have mainly focused on high Cr (17% Cr steel), and the effects of high purity on low Cr have not been clarified.

In addition, the high-purity ferritic stainless steels that have been studied so far have poor ridging properties due to their high Cr content, have limited casting and hot rolling conditions, and have the disadvantage of requiring large amounts of expensive elements to be added. was there.

The present inventors conducted various experiments in order to compensate for the shortcomings of conventional methods and to invent a ferritic stainless steel that is inexpensive, has excellent workability and corrosion resistance, and is not affected much by manufacturing methods. As a result, corrosion resistance was significantly improved by reducing 0 at low P and low S paces, and C
We have discovered that by actively utilizing N, processability can be improved without affecting the manufacturing method.

Furthermore, by adding carbonitride-forming elements such as Tl and Nb, the processability is excellent even if the limits on the amounts of C, N and Cr are removed, and these elements and Cu + Ni can be combined with the amount of S. We have found that corrosion resistance can be significantly improved by adding the required amount. It has been revealed that the above objective can be achieved by combining the above results.

That is, the gist of the present invention is nine points in total.

(1) C: 0.005-0.07% by weight percentage, St
<3.0%.

Mn: (1.03-5.0%, P<0.020%,
S<0.0010%, Cr: 9.0-15.0
%, At: 0.02-0.2%, N: 0.00
5 to 0.15%, O < 0.003.0%, and the remainder is Fe and unavoidable elements, and satisfies the relationship that Cr, C, and N appear in the shaded area in Figure 1. Ferritic stainless steel with excellent workability and corrosion resistance.

(2) c: o, oos~0.07%, si in weight percentage
≦3.0%.

Mn: 0.03-5.0%, P≦0.020%, S<
0.0010%.

Cr: 9.0-15.0%, p, t: o,
02~o, 2%, N: 0.005~0.15%
, 0.0030% of O, in addition to this, one or two types of Te, Nl and Cu are added in the range of 40×S to 2.0% depending on the amount of S.
Contains seeds, the remainder being Fe and unavoidable elements, and
A ferritic stainless steel with excellent workability and corrosion resistance, characterized in that Cr, C, and N satisfy the relationship shown in the shaded area in FIG.

(3) Weight percentage Tec: 0.005-1), 07%
, Si<3.0%.

Mn: 0.0:3-5.0%, P<0.020%
, sri 0.0010%, Cr: 9.0-15.0%,
AA: 0.02-0.2%, N: 0.005-0.
15%, O<0.0030%X In addition to this, Mo,
'l'i.

Nb+V+Zr, 40×S~ for B and Mo
2.0%r Tt lNb, v, 2 for Zr
Ferritic stainless steel with excellent workability and corrosion resistance, containing one or more types of 0XS-Q, 5%, and B in the range of <0.010%, with the remainder consisting of Fe and unavoidable elements. steel.

(4) Weight i percentage - t'c: 0.005-0.
07%, St<3.0%.

Mn: 0°03~5.0%, P<0.020%,
S, <0.0010%.

Cr: 9.0-15.0%, kl:
0.02-0.2%, N: 0.005-0.15%,
O<0.030%, in addition to this, Ni, Cu and S
Contains one or two types in the range of 40×S to 2.0% depending on the amount, and further contains Mo+ Tj' r Nb, V,
40XS ~2.0% for Zr, B and Mo,
20×S for Ti r Nb r V r Zr
~(For 1,5q6, B, it contains one or more kinds in the range of <0.010.chi), and the remainder is Fe and unavoidable elements. Ferrite with excellent workability and corrosion resistance. stainless steel.

Next, the technical basis of the present invention will be explained in detail.

Figure 2 shows the relationship between the amount of γ phase produced during hot rolling heating and the workability of a cold rolled annealed sheet, and the hot rolled sheet was annealed. The ridging property T value, which is the most important indicator of the workability of ferritic stainless steel, is 15% or less C
In steel containing r, the more the γ phase generated during hot rolling heating, the better, and when the amount of γ phase is 15% or more, good processing characteristics are exhibited. Conventionally, in high Cr steel (17%Cr@), γ
It has been said that phase precipitation reduces the V value, but this only occurs when the γ phase is 15 inches or less, and the low Cr content of the present invention
In this region, the recrystallization of the γ phase itself and the recrystallization of the α phase near the γ phase due to precipitation of the γ phase are easy, and fine recrystallized grains can be obtained as hot rolled. V without it
value and ridging characteristics are improved.

FIG. 3 shows an investigation of the effect of Cr1CIN on the amount of γ phase produced during the usual hot rolling heating at 1000 to 1250°C. The precipitation of γ phase decreases as the amount of Cr increases, and increases as the amount of (C+N)i increases. Even when heated at 1000°C, where the precipitation of the γ phase is minimal, the amount of Cr is 12%.
15% even if the (C+N) amount is less than 0.01% if it is below
The above γ phase precipitates, but if the Cr amount exceeds 12%, C
If the amount of (C0N) is not increased according to the amount, the amount of γ phase will be 1
If the amount of Cr is not more than 5% and the amount of Cr is 15%, the amount of (C1N) is required to be more than 0.02%.

FIG. 4 shows the relationship between the corrosion resistance and zero content of a cold rolled annealed plate of 9% Cr steel with low P1 and low S. 0 amount is 30
When the content is less than ppm, corrosion resistance is significantly improved.

That is, the low P that is achieved with conventional high purity steel.

By making it low in addition to low S, corrosion resistance equivalent to SUS 430 can be obtained even with 9% Cr plow.

FIG. 5 shows the relationship between the corrosion resistance of a cold rolled annealed plate and Cu and S for 11% Cr steel with low P and low 0. Corrosion resistance is significantly improved when the S content is 0.010% or less and the Cu content is S content x 40 or more. This is because insoluble C is substituted for MnS, which combines Cu with S and deteriorates corrosion resistance.
This is to form uS inclusions.

The required amount of Cu at this time is 40XSi.

Figure 6 shows the investigation of the effects of Ti and S on the corrosion resistance of 11% Cr steel with low P and low O content. Significantly improves rigidity. This is to form TiS as in the case of Cu. The required amount of Ti at this time is 20XS or more. In addition, Ni, Mo+Nb+■・Zr also show the same tendency as Tt and Cu, and the required amount is 4oxsffi or more in Nil MO h Nb + v
* At zr, the amount is more than 20XS.

Figure 7 shows 7 of 13Cr steel with low P, low S, low C1 and low N.
The graph shows the relationship between Ti content and the ridging properties. By increasing Ti and t, the value and ridging characteristics are significantly improved. Adding Ti reduces the amount of γ phase during hot rolling, but improves workability.
This is because TiN and Ti(CN) precipitate and the crystal grains become finer after hot rolling. Such an effect is Nb+
The same holds true for Zrt V+ B+ Mo. Therefore, Tit Nb, Zr, L B+ Mo
When Cr is added, the relationship between Cr and (C+N) shown in FIG. 1 becomes unnecessary.

As mentioned above, corrosion resistance is significantly improved by lowering 0 in addition to low P and low S, and even with 9% Cr steel, SUS 43
Corrosion resistance equivalent to that of 0 can be obtained. In addition, depending on the amount of Cr, C
By actively using N, the amount of γ phase during hot rolling heating can be used to reduce the temperature and time of hot rolled sheet annealing, or even omit annealing altogether, which has little effect on manufacturing conditions. High workability can be obtained without any damage. Also, Cut
Nil TL MO# Nb.

V and Zr improve corrosion resistance when added in an amount equal to or more than the amount of S. Also, Tin Mo+ Nb, V
, When carbonitride-forming elements such as Zr+B are added, γ
Even when the amount of phase is 15% or less, it has remarkable high workability. Such an invention is extremely innovative in order to supply ferritic stainless steel IFL with excellent workability and corrosion resistance at a low cost, and exhibits a powerful effect.

The reasons for limiting each component in the present invention will be described below.

In a low P, low S, low O base, C is not harmful to workability and corrosion resistance, but increases the γ phase generated during hot rolling, so it improves ridging properties. However, when it is contained in excess, it increases the hardness of the hot-rolled sheet and deteriorates the ductility of the cold-rolled annealed sheet. Also, reducing the C range to less than 0.005% requires a significant increase in cost.
~Q, 070%.

Sl is an element necessary for deoxidation, low P, low S, (at Mr. The noise characteristics deteriorate. Therefore, the upper limit was set at 3.0%. 4Mn is an element necessary for deoxidation, has a small effect on corrosion resistance at low P, low S, and low O paces, and is an effective element for generating the γ phase during hot rolling. However, if it is contained in excess, the hardness of the as-hot-rolled product increases, so the range is limited to 0.03 to 5.0.
%.

It is an element that deteriorates pH corrosion resistance and pH value, and the upper limit is 0.
．． 020tI6.

S is an element that deteriorates corrosion resistance, ) value and ductility, and is particularly harmful to corrosion resistance, and its upper limit is 0.0010.
%.

Cr is an essential element in ferritic stainless steel, and when it is based on low P, low S, and low O, it greatly improves corrosion resistance at 9% or more. However, if it is contained in a large amount, the γ phase during hot rolling decreases, deteriorating workability and increasing costs. Therefore, the range was set to 9.0 to 15.0%.

kA is an element effective for deoxidation, υ is the yield point of the cold-rolled annealed plate,
Reduces elongation at yield point. However, if it is contained in large amounts,
The γ phase during hot rolling decreases and the ridging properties deteriorate. Therefore, the range was set to 0.02 to 0.2 inches.

It has the same effect as Nf'iC, and low P, low S, and low O paces are not harmful to workability and corrosion resistance, but increase the γ phase generated during hot rolling, thereby significantly improving ridging properties. However, when it is contained in excess, it increases the hardness of the as-hot-rolled sheet and deteriorates the ductility of the cold-rolled annealed sheet. Further, since reducing the N content to less than 0.00% would result in a significant increase in cost, the N content was set in the range of 0.005% to 0.15%.

The C+N content is within the shaded range in FIG. 1 depending on the Cr content. When the Cr content exceeds 12%, as mentioned above, the C0N content must be 0P01% or more as a condition for the amount of γ phase precipitation to be 15% or more when heated at 1000°C, and the lower limit thereof. is the lower limit value 0 at a Cr content of 15
．． It increases linearly as the Cr content increases up to 0.02%.

When the Cr content is 12% or less, the C+N content is 0.01
Even if it is less than
Although it is 5% or more, the lower limit of C+N is set to 0.01 inch based on the lower limits of each of C and N mentioned above. On the other hand, if the C+N content becomes too large, the γ amount during hot-rolling becomes saturated and the hardness in the as-hot-rolled state becomes extremely high, so the upper limit of C+N was determined according to the Cr content. In other words, the upper limit of C0N is 't' from 0.10% when cr (4:9%).
0.20 when the Cr content is 15%. % increases linearly with increasing Cr content.

0 significantly deteriorates corrosion resistance on a low P and low S base.

Therefore, the upper limit was set at 0.0030%.

Cu*Ni improves corrosion resistance with low P and low 0 pace. The effect is more than 40 times that of Sl.

Furthermore, these elements increase the γ phase during hot rolling and improve workability. However, if it is included in a large amount, the effect will be saturated and the cost will increase, so the range is limited to 40 x S to 2.
It was set to 0%.

Mo+TinNbl'v, Zr, and B all reduce the γ phase during hot rolling, but they form carbides or nitrides and refine the crystal grains after hot rolling, thereby improving workability. Also, Mo+ Tin Nb+ Vt Zr has low P.

Improves corrosion resistance at low S and low O paces, and the effect is M
o is more than 40 times that of Sl, Tin Nb + Vt Zr
In this case, it is exhibited at more than 20 times that of Sl. However, if a large amount of these elements is included, the effect will be saturated and the cost will increase, so the range for MO is 40XS to 2.
0%, Ti, Nb, V, Zr”?? is 20×S ~ 0.5
%, B was 0.010 inches or less.

Examples of the present invention will be described below.

As the invention steel and comparative steel shown in Table 1, low C-13C
R steel, 5US430, was melted according to the usual stainless steel melting method. The steel of the present invention has low P,
Low S and O. The steel produced in this manner was subjected to conventional hot rolling and hot rolled plate annealing, and then subjected to one cold rolling process to obtain a cold rolled thin plate of 07 size. The properties of these thin plates are shown in Table 2. The steel of the present invention is SUS 43'0, which is the conventional steel A13.
It has excellent workability and corrosion resistance that is equal to or better than that of .

Table 2 Material properties of steel shown in examples

[Brief explanation of drawings]

Figure 1 shows the relationship between Cr content and (C+N)i of the steel according to the present invention.
Figure 3 shows the influence of the amount of γ phase during hot rolling heating on the song height and V value of cold rolled annealed sheets when heated at 000 to 1250°C during hot rolling. Figure 4 shows the effects of Cr r (C + N) amount and hot rolling heating temperature on the amount of γ phase generated when steel is heated at 1000 to 1250°C during hot rolling. S9%Cr4ti
In the cold-rolled annealed sheet of No. 1, the pitting potential was measured in a CA-1500 ppm solution prepared using NaCt at 35 °C under deaerated conditions, and the 05 attack NaCA solution was JIS Z 2371.
Figure 5 shows the effect of the amount of O on the rusting rate when sprayed for 24 hours according to the salt spray test of %NaCt solution J
Figure 6 shows the influence of Cu and S amounts on the degree of rusting when sprayed for 24 hours in accordance with the IS Z 2371 salt spray test. Fig. 7 is a diagram showing the effect of Tll5 amount, which did not reach the level of rusting when 0.54 NaCt liquid was sprayed on a cold rolled annealed plate of low 011% Cr steel for 24 hours in accordance with the salt spray test of JISz2371. is a diagram showing the influence of Tl bone on the song height and V value of a cold-rolled annealed plate when a low C, N, P, S, 013% Cr steel is heated at 1200° C. during hot rolling. Symbols in Fig. 1: ○: 9% Cr steel Δ: 11 Cr steel B: 15% Cr copper ×: 17 Cr steel Symbols in Fig. 5 and 6 ◎: No rusting A: No rusting None , ) No. 2 Figure Silk 7 Bacteria Continued from page 1 0 Inventors Hara Seibu 2nd Department Kitakyushu City 1-1-1 Edamitsu, Hatto-ku Nippon Steel Corporation Production Technology Laboratory 0 Inventors Tetsube Takeshita To Kitakyushu City, 1-1-1 Edamitsu, Hatto-ku, Nippon Steel Corporation, Industrial Technology Research Institute Procedure Amendment (Voluntary) June 18, 1982, 2, Title of Invention Ferritic system with corroded processability and corrosion resistance Stainless steel 3, relationship with the case of the person making the amendment Patent applicant Takeshi 1), representative of Nippon Steel Corporation, 2-6-3 Otemachi, Chiyoda-ku, Tokyo (665). 4. Agent Address: 100 2-4-1 Marunouchi, Chiyoda-ku, Tokyo Range (1) C: 0.07%, St<3.0% by weight 1%
. Mn: 0.03-5.0%, P: 0.020%,
S<0.0010%. Contains 0.0030% of O, the remainder is Fe and unavoidable elements, and Cr, C, and N are a + b + in Figure 1.
A ferritic stainless steel with excellent workability and corrosion resistance, characterized in that it satisfies the relationship expressed by the diagonal line drawn by the straight line connecting the points c + d + e. (2) Weight percentage: C: 0.07%, Si<3.0%
. Mn: 0.03-5.0%, P: 0.020%,
S<0.0010%. In addition to this, Ni and Cu are added in the range of 40xS to 2.0% depending on the amount of S.
A ferritic stainless steel with excellent workability and corrosion resistance, which satisfies the relationship expressed by the line, with the remainder consisting of Fe and unavoidable elements. (3) Weight percentage c: Kuo, oy%, St<:3.0
%. Mn: 0.03-5.0%, P<0.020%
, S<0.0O10%. 0.0O3o%, in addition to this, Mo, Ti, Nb
, V, Zr lB for MO 40×S ~ 2,0%
, Tl, Nb, v, and zr in the range of 20×S to 0.5%, and B in the range of 0.010%, and the remainder consists of 1tFe and unavoidable elements. Ferritic stainless steel with excellent workability and corrosion resistance (4) C: 0.07% by weight, St <3.
0chi. Mn: 0.03-5.0%, P: 0.020%, S
<0.001 (1%. 0<0.0030%, in addition to this, it contains one or two types of Ni and Cu in the range of 40 × S to 2.0% depending on the amount of S, and further Mo , Ti, Nb, V, Zr, B to Mo
For 40XS ~2.0%, Ti, Nb, V, Z
For r, 20×S ~ 0.5 excellent, for B, 0.
A ferritic stainless steel with excellent workability and corrosion resistance, characterized in that it contains one type or two or more types of 1lt in the range of 0.010%, and the remainder consists of Fe and unavoidable elements. 3. Detailed Description of the Invention The present invention relates to a ferritic stainless steel that is mainly used in thin stainless steel sheets and has excellent workability and corrosion resistance, and is inexpensive. Traditionally, in the field of stainless steel thin plates, STJ'
S 304 (18% Cr-8% Ni steel), SUS 4
30 (17% Cr steel) has been used. However, these steels are very expensive because they contain a large amount of Cr or Ni. Further, although SUS 430 is cheaper than SUS 304, it has the drawbacks of inferior workability and corrosion resistance. On the other hand, looking at recent demand trends, demand for stainless steel sheets is expected to increase as living standards become more sophisticated and applications for use expand.
There is now a demand for stainless steel that has workability and corrosion resistance equivalent to or better than 430, and is inexpensive. SUS is a conventionally used inexpensive stainless steel.
410, Al5I 40p, etc. Recently, these steels have been improved in processability and weldability by reducing carbon content and adding alloys, but corrosion resistance still remains.
It is inferior to US 430. On the other hand, with recent advances in refining technology, it has become possible to reduce P and S at a relatively low cost.
, research on high purification began to be actively conducted. However, studies on high purity have mainly focused on high Cr (17% Cr steel), and the effects of high purity on low Cr have not been clarified. In addition, the high-purity ferritic stainless steels that have been studied so far have poor ridging properties due to their high Cr content, have limited casting and hot rolling conditions, and have the disadvantage of requiring large amounts of expensive elements to be added. There was a thunderstorm. The present inventors conducted various experiments in order to compensate for the shortcomings of conventional methods and to invent a ferritic stainless steel that is inexpensive, has excellent workability and corrosion resistance, and is not affected by the manufacturing method 1c. As a result, corrosion resistance was significantly improved by reducing O at low P and low S paces, and by using C and N according to the amount of Cr, there was no effect on the manufacturing method, and I
! It has been found that processability can be improved without receiving l. Furthermore, by adding carbonitride-forming elements such as Ti and Nb, the processability is excellent even if the limits on the amounts of C, N and Cr are removed.
We have found that corrosion resistance can be significantly improved by adding the required amount. It has been clarified that the above object can be achieved by combining the above results. That is, the gist of the present invention is as follows. (1) M position fraction: C: 0.07%, St<3.0%
. Mn: 0.03-5.0%, P 0.020%,
S<0.0010% *Cr: 9.0-15.0
%, At: <o, 2%, N"ku0.15%
, O and 0.0030%, the remainder consists of Fe and unavoidable elements, and Cr, C, and N are ar b in Fig. 1.
A ferritic stainless steel with excellent workability and corrosion resistance, characterized in that it satisfies the relationship shown in the hatched area surrounded by straight lines connecting each point of + Cr d He. (2) C: 0.07% by weight, St<3.0. Mn: 0.03-5.0%, pco, o2o%, s
0.0010%, Cr: 9.0-15.0%
, At:<0.2%. N: 0.15%, O (0,0030%, in addition to this, Ni and Cu were added depending on Si, 40XS ~ 2.(l
Contains one or two types within the range of
A ferritic stainless steel with excellent workability and corrosion resistance, which satisfies the relationship shown in the shaded area surrounded by straight lines connecting points b+c, d-, and e. (3) Weight percentage: C: 0.07%, Si<3.0%
. Mn: 0.03-5.0%, P<:0.02
0%, S<0;0010%. Cr: 9.0-15.0%, At: <0.2%, N
:<0.15%. 0.0030%, in addition to this, Mo,'ri
,Nb,v. Zr, B to Mo is 40XS ~2.0%
, Ti. Nb, V, Zr flc tweet is 20XS-0,
5%, and 1 or 1- in the range of 0.010% for B.
A ferritic stainless steel with excellent workability and corrosion resistance, which is characterized by containing two or more types of t and the remainder consisting of Fe and unavoidable elements. (4) C in weight percentage: 0.07%, sl<a, 0%
. Mn: 0.03~5.0%, Pri 0°020%
, S 0.0010%. Cr: 9.0-15.0%, At: 0.2%
, N: <0.15%. o<c) io 30%, in addition to this, Ni,
Cu is S, 1 in the range of 40XS to 2.0% depending on li
Contains one or two species, and further contains Mo, Ti, Nb, V, zr
+B to 40XS for Mo ~2.0%, Ti,
Nb, V, Zr K temperature is 20×S ~ 0.5%, B
K-) A ferritic stainless steel with excellent workability and corrosion resistance, characterized by containing one or more types in the range of i'0f < 0.010%, with the remainder consisting of Fe and unavoidable elements. Next, the technical basis of the present invention will be explained in detail. FIG. 2 shows the relationship between the amount of γ phase generated during hot rolling heating and the workability of a cold rolled annealed sheet, and the hot rolled sheet is annealed. The ridging property r value, which is the most cost-effective indicator of the workability of ferritic stainless steel, is
The more the γ phase produced during hot rolling heating, the better the steel containing . Conventionally, in high Cr steel (17% Cr steel), γ
It has been said that phase precipitation reduces the r value, but this occurs when the γ phase is 15% or less, and low Cr as in the present invention
In this region, the recrystallization of the γ phase itself and the recrystallization of the α phase in the vicinity of the γ phase due to precipitation of the γ phase are easy, and fine recrystallized grains can be obtained as hot rolled. Even without annealing
value and ridging characteristics are improved. FIG. 3 shows an investigation of the influence of Cr r Cz N on the amount of γ phase generated during the usual hot rolling heating at 1000 to 1250°C. The precipitation of γ phase decreases as the amount of Cr increases, and increases as the amount of Cr increases.
If the r amount is 12% or less, the (C1N) amount is o, ooi%
Even if the amount of ar is less than 15%, γ phase will precipitate, but if the amount of ar is less than 12
%, the amount of γ phase will not exceed 15% unless the amount of (C + N) is increased according to Cm, and if the Cr lid is 15%, (
C1N) amount is required to be 0.01% or more. FIG. 4 shows the relationship between the corrosion resistance and the O content of a cold rolled annealed plate of 9% Cr steel with low P1 and low S. O amount is 30 pp
When it is less than m, corrosion resistance is significantly improved. That is, the low P that is achieved with conventional high purity steel. In addition to low S, corrosion resistance equivalent to SUS 430 can be obtained even with 9% Crf14. FIG. 5 shows the relationship between the corrosion resistance of a cold-rolled annealed plate and Cu and S for 11% Cr steel with low P and low 0. S amount is 0.010% or less and Cu amount is S amount x 4
Corrosion resistance is significantly improved when it is 0 or more. This is because Cu combines with S to form insoluble CuS inclusions in place of MnS, which deteriorates corrosion resistance. The required amount of Cu at this time is 40×S amount. Figure 6 shows the investigation of the influence of Ti and S on the corrosion resistance of 11% Cr steel with low P and low O content. Significantly improves corrosion resistance. This is to form TiS as in the case of Cu. The required amount of Ti at this time is 20×S amount or more. Also, Ns * Mo + Nb * V,
Zr also shows the same tendency as Ti and Cu, and the amount of Ni, Mo, and Ti must be 40 x the amount of S or more, and the amount of Nb, V. For Zr, the amount of S is 20× or more. FIG. 7 shows the relationship between the amount of Tl and the rkzv jing properties of 13Cr steel with low P, low S, low C2 and low N. 7 value by increasing the amount of Ti. Ridging properties are significantly improved. Adding Ti reduces the amount of γ phase during hot rolling, but improves workability and results in the precipitation of TIN, Ti (CN), and refinement of grains after hot rolling. This is to do so. Such an effect holds true for Nb+Zr+V, B, and Mo as well. Therefore, when Ti, Nb, Zr, V, B, and Mo are added, the relationship between the needle and (C+N) in FIG. 1 becomes unnecessary. As mentioned above, corrosion resistance is significantly improved by lowering 0 in addition to low P and low S, and even with 9% Cr steel, SUS, 43
Corrosion resistance equivalent to that of 0 can be obtained. Also, depending on Cr new, C,
By actively utilizing N, the amount of γ phase during hot rolling heating can be used to improve production conditions, such as hot-rolled sheet annealing or annealing at lower temperatures and shorter times, or even omitting annealing altogether. High workability can be obtained without being affected. Also, Cu, Ni
, Ti + Mo, Nb, and VtZr improve corrosion resistance when added in an amount equal to or more than the amount of S. Also, Ti
, Mo, Nb, V, Zr*B: When carbonitride-forming elements f such as B are added, copper with remarkable high workability can be obtained even if the amount of γ phase is 15% or less. This invention is extremely innovative and highly effective in providing ferritic stainless steel with excellent workability and corrosion resistance at a low cost. The reasons for the use of each component in the present invention will be described below. At low P, low S, and low 0 paces, C is harmful to workability and corrosion resistance, and increases the γ phase generated during hot rolling, thereby significantly improving ridging properties. However, excessive carbon content increases the hardness of the hot-rolled sheet and deteriorates the ductility of the cold-rolled annealed sheet.
% or less. Si is an element necessary for deoxidation, and improves corrosion resistance at low P, low S, and low 0 paces. However, if it is contained in excess, the γ phase during hot rolling decreases and the ridging properties deteriorate. For this reason, the upper limit was set at 3.0%. Mn is a strong element for deoxidation, has a low P, low S, and low zero pace effect on IT corrosion resistance of 1-t/J·, and is an effective element for generating all of the γ phase during hot rolling. However, excessive inclusion of ferrite increases the hardness of the as-hot-rolled steel, so the range is set to 0.03 to 5.0%. P is an element that deteriorates corrosion resistance and T value, and the upper limit is 0.
．． The score was 020 A. S is an element that deteriorates corrosion resistance, 7 value, and ductility, and is particularly important for corrosion resistance, and its upper limit is 0.0010.
%. Cr is an essential element in ferritic stainless steel, and at low P, low S, and low 0 paces, it greatly improves the corrosion resistance by 9% or more. However, if it is contained in a large amount, the γ phase during hot rolling decreases, deteriorating workability and increasing costs. Therefore, the range was set to 9.0 to 15.0%. At is an effective element for deoxidation and lowers the yield point and yield point elongation of cold rolled annealed sheets. However, if it is contained in a large amount, the γ phase decreases during hot rolling and the ridging properties deteriorate.
Ru. Therefore, the range was set to 0.2- or less. N has the same effect as C, and when based on low P, low S, and low O, it is not harmful to workability and corrosion resistance, and increases the γ phase generated during hot rolling, so it significantly improves ridging properties. However, if excessively contained, the hardness of the hot-rolled sheet 1 increases and the ductility of the cold-rolled annealed sheet deteriorates, so the range of N is set to 0.15% or less. The C-1-N content depends on the Cr content as shown in a(
9,0), b(12,0), c(15,0,01), d
(15°0°20), e(9,0,10).If the Cr content exceeds 12%, as mentioned above, As a condition for the amount of γ phase precipitation during heating to be 15% or more, the C1N content must be 0.001 cm or more, and its lower limit is 0.1
It increases linearly as the amount of Cr increases up to the lower limit of 0.01 inch at 115%. If the Cr amount is 12% or less, even if the C-1-N content is less than 0.001-
The amount of γ phase precipitation during heating at °C is 15% or more. On the other hand, if the C+N-containing plate becomes too large, the γ amount during hot-rolling becomes saturated and the hardness in the as-hot-rolled state increases significantly, so the upper limit of C+N was determined according to CrJl. That is, the upper limit value of C1N increases from 0.10% when the Cr content is 9% to 0.20% when the Cr content is 01115% to the lCC striped line as the Cr content increases. 0 significantly deteriorates corrosion resistance at low P and low S paces. Therefore, the upper limit was set at 0.0030%. Cu and Ni improve corrosion resistance with low P and low 0 pace. The effect is exhibited at 40 times or more the amount of S. Furthermore, these elements increase the γ phase during hot rolling and improve workability. However, if it is included in a large amount, the effect will be saturated and the cost will increase, so the range is limited to 40 x S to 2.
It was set to 0%. Mo + Ti + Nb + V + Zr + B
ij both reduce the γ phase during hot rolling, but carbides,
Alternatively, nitrides are formed to refine the crystal grains after hot rolling, thereby improving workability. Also, Mo, TitNb+V, zr
It improves corrosion resistance at low P, low S, and low O paces, and its effect ii is more than 40 times that of Sfi for Mo, and more than 40 times that of Sfi for Ti.
, Nb+V, and Zr, it is exhibited at 20 times or more the amount of S. However, if a large amount of these elements is included, the effect will be saturated and the cost will increase.
t20X8~0.5山, B was 0.010% or less. Examples of the present invention will be described below. As the invention steel and comparative steel shown in Table 1, low C-13C
r steel, SUS 430, was melted according to a normal stainless steel melting method. The steel of the present invention was made low in P, S, and O by blowing Ca-based flux in a ladle and sufficiently deoxidizing with At. The thus produced steel was subjected to conventional hot rolling and hot rolled plate annealing, and then subjected to one cold rolling process to form a cold rolled thin plate of 90.76 mm. The properties of these thin plates are shown in Table 2. The steel of the present invention exhibited excellent workability and corrosion resistance equivalent to or better than SUS 430, which is the conventional steel A13. Table 2: Material properties 4 of the steel shown in the examples, brief explanation of the drawings. Figure 1 is a region diagram showing the relationship between the Cr content and (C0N) content of the steel according to the present invention, and Figure 2 is a 9-17% Cr steel 10
Figure 3 shows the influence of the amount of r-phase during hot rolling heating on the sliding height and F value of a cold rolled annealed plate when heated at 00 to 1250°C during hot rolling. 1
r generated when heated during hot rolling at 000-1250℃
Figure 4 shows the effects of Cr, (C+N) content, and hot rolling heating temperature on the amount of phase.
A-35°C in 1500 ppm solution. Pitting potential measured under deaerated conditions, 0.5% NaCt solution J
Figure 5 shows the influence of the amount of O on the degree of rusting when sprayed for 24 hours in accordance with the IS Z 2371 salt spray test. ．．
A diagram showing the influence of Cu and S amounts on the degree of rusting when 5% NthC1 solution is sprayed for 24 hours in accordance with the JIS Z 2371 salt spray test. Figure 6 shows low P, low 011
%Cr steel cold rolled annealed plate with 0.5% NaCt solution JISZ
A diagram showing the influence of Ti and S amounts on the degree of rusting when sprayed for 24 hours in accordance with the salt spray test of 2371,
Figure 7 shows low C, N, P, 'S, 013% Cr steel at 120
FIG. 3 is a diagram showing the influence of the amount of Ti on the gluing height value of a cold-rolled annealed sheet when heated at 0° C. during hot rolling. Symbols in Figure 1: ○: 9-inch Cr steel Δ: 11-inch Cr steel 0215% Cr steel n G Full surface rusting Figure 1 Cr ('10

Claims (4)

[Claims] (1) C by weight percentage: 0.005-0.07%, 81
<3.0%, Mn: 0.03-5.0%, P<0.
020%, Soo, ooio%, Cr: 9. O~1
5.0%, At: 0.02-0.2%, N: 0
．． 005 to 0.15%, o < o, o o' 30%, the remainder is Fe and inevitable elements, and Cr
A ferritic stainless copper having excellent workability and corrosion resistance, characterized in that +clN satisfies the relationship shown in the shaded area in FIG. (2) C: 0.005 to 0.07, S in weight percentage
Iri: 3.0%, Mn: 0.03~5.0%, P: 0.020%, S: 0.0010%, Cr: 9.0~
15.0%, A1. : 0.02~o, 2chi, N
: 0.005-0.15%, 0<0.0030%,
In addition to this, Ni and Cu were added by 40X depending on the amount of S.
Contains one or two types in the range of S to 2.0-, and the remainder is F
A ferritic stainless steel with excellent workability and corrosion resistance, characterized by 9 consisting of e and unavoidable elements, and Cr, C, and N satisfying the relationship shown in the shaded area in Figure 1.◇ (3) c: o, oos ~ 0.07 chi, Si in weight percentage
<3.0%, Mn: 0.03-5.0%, P<0
．． 020%, S≦0.0010%, Cr: 9.0
~15.0%, M: 0.02~0.2%, N
: 0.005-0.15%, O≦0.0030%,
In addition to this, Mal Ti, Nb+ V+ Zr+
B for Mo is 40×S~2.0%, Ti+Nb
+L Workability characterized by containing one or more types of Zr' in the range of 20×S to 0.5% and B in the range of <0.010%, with the remainder consisting of Fe and unavoidable elements. and ferritic stainless steel with excellent corrosion resistance. (4) C: 0.005-0.07% by weight percentage, s
Iri 3.0%, Mn: 0.03-5.0%, P<
0.020%, S<0.0010ch, Cr: 9. O~
15.0%, At: 0.02 to 0.2 inches, N: 0.
0.005~0.15%, Oku0.0030chi1. In addition to this, depending on the amount of Ni and Cut-8, 40XS ~ 2.0
% of one or two types, and further contains Mal T1
1NblV, Zr, B for MO 40XS ~2
．． os, Ti, Nb,. V+ Workability characterized by containing 1'4 stone or two or more in the range of 20 x S ~ 0.5% for Zr and ≦0.010% for B, and the remainder consisting of Fe and inevitable elements. and ferritic stainless steel with excellent corrosion resistance.