Ferritic stainless steel plate excellent in deep drawability and

Details Ferritic stainless steel plate excellent in deep drawability and Ferritic stainless steel plate excellent in deep drawability and

1999-03-29

2000-09-05

Yee, Deborah

Metal treatment

Stock

Ferrous

148609, C22C 3824, C22C 3826, C21D 804

Patent

active

061137103

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a ferritic stainless steel plate particularly excellent in the deep drawability and the anti-ridging property in ferritic stainless steel plates.


BACKGROUND ART

Ferritic stainless steel has been widely utilized in various industrial fields such as house wares, parts of motorcars, etc., as a material excellent in the corrosion resistance and the heat resistance.
The ferritic stainless steel is inexpensive as compared with an austenitic stainless steel containing a large amount of Ni but in general, is inferior in the workability and, for example, when press working is applied to a ferritic stainless steel, a surface defect called ridging is liable to cause, thereby the ferritic stainless steel is unsuitable for the use of being applied with a strong work such as a deep drawing work, etc.
Also, a ferritic stainless steel has the problems that the anisotropy (.DELTA.r) of a plastic strain ratio is large and a nonuniform deformation is liable to cause at deep drawing work.
Now, for solving the above-described problems, many attempts have hitherto been made. First, various improvements of an anti-ridging property are proposed in (a) Patent Publication (unexamined) No. 52-24913, (b) Patent Publication (unexamined) No. 56-123356, (c) Patent Publication (unexamined) No. 7-18385, (d) Patent Publication (unexamined) No. 9-53155, etc.
The stainless steel of the above-described (a) contains from 0.03 to 0.08 wt. % C, not more than 0.01 wt. % N, not more than 0.008 wt. % S, not more than 0.03 wt. % P, not more than 0.4 wt. % Si, not more than 0.5 wt. % Mn, not more than 0.3 wt. % Ni, from 15 to 20 wt. % Cr, and from 2.times.N to 0.2 wt. % Al.
The stainless steel of the above-described (b) contains not more than 0.1 wt. % C, not more than 1.0 wt. % Si, not more than 0.75 wt. % Mn, from 10 to 30 wt. % Cr, not more than 0.5 wt. % Ni, not more than 0.025 wt. % N, and from 2 to 30 ppm of B or further containing one or more kinds from 0.005 to 0.4 wt. % Al, from 0.005 to 0.6 wt. % Ti, from 0.005 to 0.4 wt. % Nb, from 0.005 to 0.4 wt. % V, from 0.005 to 0.4 wt. % Zr, from 0.02 to 0.5 wt. % Cu, not more than 0.05 wt. % Ca, and not more than 0.05 wt. % Ce.
In the stainless steel of the above-described (c), the content of Cr is from 3 to 60 wt. %, the contents of C, S, and O are reduced, and the content of N is from 0.03 to 0.5 wt. %.
The stainless steel of the above-described (d) contains not more than 0.01 wt. % C, not more than 1.0 wt. % Si, not more than 1.0 wt. % Mn, not more than 0.01 wt. % S, from 9 to 50 wt. % Cr, not more than 0.07 wt. % Al, not more than 0.02 wt. % N, not more than 0.01 wt. % O, and C and N in the conditions satisfying N(wt. %)/C(wt. %).gtoreq.2 and 0.006.ltoreq.[C(wt. %)+N(wt. %)].ltoreq.0.025, and further Ti in the conditions satisfying {Ti(wt. %)-2.times.S(wt. %)-3.times.O(wt. %)}/[C(wt. %)+N(wt. %)].gtoreq.4 and [Ti(wt. %)].times.[N(wt. %).ltoreq.30.times.10.sup.-4.
However, in these techniques, when a severe deep drawing work is carried out, ridging occurs and thus they cannot say sufficient techniques. Also, there is a problem that the occurrence of a nonuniform deformation at a drawing work is not improved.
On the other hand, as a technique of improving the anisotropy of the plastic strain ratio, a ferritic stainless steel containing not more than 0.03 wt. % C, not more than 1.0 wt. % Si, not more than 1.0 wt. % Mn, not more than 0.05 wt. % P, not more than 0.015 wt. % S, not more than 0.1 wt. % Al, not more than 0.02 wt. % N, from 5 to 60 wt. % Cr, from 4.times.(C+N) to 0.5 wt. % Ti, from 0.003 to 0.02 wt. % Nb, and from 0.0002 to 0.005 wt. % B or further containing at least one kind of from 0.0005 to 0.01 wt. % Ca and from 0.1 to 5.0 wt. % Mo is disclosed in (e) Patent Publication (unexamined) No. 8-20843.
By the technique, certainly, Ar becomes about 0.15 or lower and the anisotropy is improved but the anti-ridging property is insufficient.
Also, techniques of improving the deep drawability are disclosed in (f) Patent Publication (unexamine

REFERENCES:
patent: 4515644 (1985-05-01), Sawatani et al.
patent: 5868875 (1999-02-01), Yashitake

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