TEXTURE AND MICROSTRUCTURE EVOLUTION DURING COLD-ROLLING OF A STRIP CAST AND OF A HOT-ROLLED AUSTENITIC STAINLESS-STEEL

The microstructure and texture evolution of a strip cast and of a hot rolled austenitic stainless steel (18% Cr, 8.5% Ni) during cold rollin g was studied (maximum thickness reduction Delta d/d(0) = 80%). The mi crostructure of the hot band was homogeneous through the sheet thickne ss, except that in the centre layer a small volume fraction of martens ite appeared. The hot band texture revealed a through-thickness gradie nt which was discussed in terms of the shear distribution during hot r olling. The microstructure of the cast strip showed globular grains wi th martensite was attributed to the deformation of the solidified film s in the rolling gap. The strip cast sample revealed a weak texture fi bre close to {001}[uvw] which was interpreted in terms of growth selec tion during solidification. During cold rolling in both types of sampl es the volume fraction of martensite increased up to similar to 50 vol .% (80% reduction). The cold rolling texture of the austenite was in b oth cases characterized by {011}[211] and {011}[100]. The cold rolling texture of the hot band was stronger then that of the strip cast samp le which was attributed to the influence of the starting texture and g rain size. The cold rolling texture of the austenite was simulated by means of a Taylor type model considering grain interaction and the so- called card glide mechanism. The martensite was characterized by {211} [011] and {111}[211]. The former component was interpreted in terms of the relaxation of shear constraints. The latter was attributed to sel ective phase transformation of {011}[211] (austenite) to {332}[113] (m artensite) which then rotated towards {111}[112]. The rolling textures of the martensite were simulated using a Sachs type deformation model . Copyright (C) 1997 Acta Metallurgica Inc.