Keijiro Suzuki

Ridging Phenomenon Related to the Undulated Segregation-pattern on Transverse Section in Ferritic Stainless Steel

Ridging phenomenon of 18% Cr stainless steel is studied in connection with the segregation-pattern of Cr and C which shows undulations very similar to the ridging on the transverse section of hot rolled and cold rolled sheet.(1) A laminated segregation pattern is observed at the center layer of transverse cross-section of hot rolled sheet. The segregation-pattern becomes wavy and extends through the thickness of cold rolled and annealed sheet.(2) The segregation-pattern shows undulations very similar to the profile of ridging after stretching of 20% in the rolling direction.(3) The height of ridging is well correlated with that of undulated segregation-pattern.(4) Ridging phenomenon is thought to be a manifestation of underlying pattern of undulated segregation of Cr and C, which is farmed and retained in the hot and cold rolling process, by tensile elongation.

Drawability of stainless steel sheets

Abstract Stainless steels can be classified into two categories, i.e. austenitic and ferritic. These materials are different in crystalline structure: where austenitic stainless steel is face-centered cubic, ferritic stainless steel is body-centered cubic. In general, the quality of stainless steel tends to be assessed by its magnetic properties: it is believed that austentic stainless steel is better than ferritic stainless steel, because it is non-magnetic, but, in fact, the drawability of — magnetic — ferritic stainless steel is somewhat better than that of austenitic stainless steel. Press forming, however, consists of both drawing and stretch forming, and thus in the press forming of stainless steel sheets, it is necessary to have a good knowledge of the metallographic factors governing stretch forming and deep drawing. In this paper, the differences between austenitic and ferritic stainless steel of the metallographic factors which control press forming, are discussed.