Ridging free deep-drawing ferritic stainless steel sheet prodn. - using warm rolling and continuous annealing steps

摘要

A ridging-free ferritic stainless steel, for deep drawing applications, is mfd. by hot rolling, coiling at 450-750 degrees C warm rolling at 450-700 degrees C with >=15% redn. in a mill installed separately from the hot rolling mill train, continuous annealing cold rolling and final annealing. During warm rolling, ferrite deforms in preference to austenite and shear of deformation bands break up the elongated grains formed by hot rolling. A weakly directional texture, which is retained after cold rolling and annealing, is formed to reduce the planar anisotropy of T values of the product. Warm rolling also allows a short time continuous anneal. to be used. The process can be carried out in the same rolling mill as used for low carbon steel sheet but modifie dby an off-line warm rolling mill. The method is esp. useful in preventing ridging in Ti-stabilised extra low carbon ferritic stainless steels caused by development of left brace 100 right brace 011 > and left brace 554 right brace 255 > textures.