Metal treatment – Process of modifying or maintaining internal physical... – With casting or solidifying from melt
Patent
1993-08-19
1995-05-02
Yee, Deborah
Metal treatment
Process of modifying or maintaining internal physical...
With casting or solidifying from melt
148651, 148325, 428606, C21D 800, C22C 3806
Patent
active
054116104
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a stainless steel foil for corrugating, which is a component for constituting metallic carriers for catalysts used in exhaust gas purification devices for automobiles, and a process for producing the same. More particularly, the present invention is concerned with a stainless steel foil which is excellent in corrugation workability, i.e., free from unfavorable phenomena, such as foil cracking and foil breaking, even when it is subjected to corrugating.
BACKGROUND ART
Ceramic honeycomb has hitherto been used in carriers for catalysts in automobiles. In recent years, however, a proposal has been made on the use of a metallic honeycomb carrier for catalysts in automobiles having performance superior to the ceramic honeycomb from the viewpoint of the performance of engines, loading, etc. Specifically, a carrier for catalysts in automobiles according to this proposal comprises a metallic honeycomb comprising of alternately wound flat stainless steel foil and corrugated stainless steel foil and a metallic jacket surrounding the metallic honeycomb. This technique is specifically disclosed in, for example, Japanese Unexamined Patent Publication (Kokai) No. 50-92286, 51-48473, 57-71898 and 58-177437.
The process for producing the above-described metallic honeycomb carriers for catalysts in automobiles (hereinafter referred to as "metallic carrier" ) comprises the following steps. (1) A 20Cr-5Al-base stainless steel provided by a melt process is subjected to hot rolling, cold rolling, etc. to form a foil material having a thickness of about 50 .mu.m. (2) The foil material is corrugated to provide a corrugated foil. (3) Then, a honeycomb material comprising of alternately wound flat foil and corrugated foil is formed and incorporated into a jacket. (4) The application of a brazing agent followed by a brazing treatment is effected to join the flat foil to the corrugated foil or to join the foil to the jacket. (5) The resultant carrier is further subjected to a treatment for carrying a catalyst thereon. In the step of cold rolling of a stainless steel among the above-described steps, since the stainless steel has a high work hardenability, it is a common practice to effect the step of once softening the material, i.e., intermediate annealing, before rolling the material into a foil having a thickness of about 50 .mu.m. Since the stainless steel foil thus provided is corrugated in the subsequent step, it is indispensable to impart sufficient corrugation workability to the foil in the step of cold rolling of the stainless steel.
Japanese Unexamined Patent Publication (Kokai) No. 56-152965 discloses a method wherein a stainless steel foil peeled by cutting from the surface of a billet is subjected to a softening annealing treatment for the purpose of facilitating the corrugation (i.e., enhancing the corrugation workability). However, in the method for improving the ductility of the foil by the annealing treatment, although the ductility of the material can be enhanced, since draw breaking of the material unfavorably occurs due to the occurrence of tension, it cannot be said that the corrugation workability of the foil can be satisfactorily improved by this method. Further, the strength of the corrugated product also becomes so low that wavy deformation is liable to occur during subsequent alternate winding of the corrugated foil and flat foil or during use of the final product. For this reason, the above-described method is not suitable for improving the corrugation workability of the foil.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a high-strength stainless steel foil for corrugating, which has improved corrugation workability of the foil and, at the same time, has a simplified foil production process through a method different from conventional methods such that the ductility of the foil is improved by an annealing treatment to ensure the corrugation workability, and a process for producing said high-strength stainless steel foil f
REFERENCES:
patent: 5228932 (1993-07-01), Shimizu et al.
European Search Report EP 92 92 3986.
Araki Jun
Fudanoki Fumio
Fukaya Masuhiro
Kasuya Masayuki
Kato Yuichi
Nippon Steel Corporation
Yee Deborah
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