Nippon Steel develops ultra-highly-formable ferritic stainless steel sheet

Nippon Steel Corporation (President: CHIHAYA Akira) has developed ultra-highly formable ferritic stainless steel sheet， ”YUSPDX”， which features drastically improved formability and deep-drawability， utilizing the high-efficiency vacuum refining and the metallurgically structure control technology applied to the integrated production process ranging from casting to final annealing cold rolling. Although ferritic in type， YUSPDX has workability and press-formability comparable to those of austenitic stainless steel represented by SUS304. With the addition of YUSPDX to the product menu， Nippon Steel has further enhanced its supply capability of diverse materials to meet customers’ specific needs and objectives.

Compared to the austenitic stainless steel containing nickel， conventional ferritic stainless steel represented by SUS430 is lower in elongation before fracture and inferior in formability. YUSPDX has drastically reduced elongation-impairing impurities by high-efficiency vacuum refining， and improved elongation to approximately 40% by enhancing the absolute value of elongation by about 10% compared to conventional SUS430. Also， by reducing the addition of titanium to the necessary minimum， it has raised the Lankford value to about 2.0 and sharply improved the drawability in press forming.

When impurities are reduced and purity is enhanced， the metallic structure of ferritic stainless steel gets coarser when cast， increasing surface irregularities called ”ridging” when the steel sheet is press-formed. Ridging not only impairs the appearance of the press-formed products but also increases the load of surface polishing after press forming. YUSPDX has succeeded in eliminating the harmful effects of high purity and virtually suppressing the occurrence of ridging after press-forming， by restraining the coarsening of the cast structure and optimally controlling the microstructure and texture structure through the integrated production process from hot to final annealing.

Compared to austenitic stainless steel， YUSPDX reduces the load to the pressing machine during forming. Also， since no cracking occurs after deep drawing， it is an ideal material for applications involving deep drawing.

Furthermore， YUSPDX is effective in cutting parts manufacturing costs. This is because ?it can be used as a substitute material for parts where the austenitic stainless steel containing a large amount of expensive nickel had to be used， ?it can lower the material cost by reducing sheet thickness or blank size of conventional ferritic stainless steel because of its excellent formability， ?it can replace parts， formerly assembled by welding several pieces， with press-formed monobloc parts and ?it can simplify the press-forming process.

NSC started the production and marketing of YUSPDX in the summer of 2001 aiming at its wider use mainly as fabricated parts of products such as combustion equipment， battery cases， automotive parts， kitchen utensils and building interior finishings.


For more information， please contact:

Mr. TENDO Masayuki， Stainless Steel Division， 03-3275-7866
Mr. KANKE Takashi， Public Relations