Effect of deformation mode on texture development in cold-rolled duplex steel

Duplex type austenic-ferritic steel 00H18N6Mo3 was cold-rolled within the r ange up to 85% of deformation taking either low or high reductions in each roll, pass (variants A and B respectively). Structure observations were per formed by means of optical microscopy. X-ray investigations included the ph ase analysis, measurements of pole figures and calculation of the orientati on distribution functions (ODFs) for the case of each phase. The texture de velopment of ferrite and austenite was analysed within the surface and cent re layers of the rolled sheets. Metallographic examination showed only slight differences in structure deve lopment between both rolling variants. Reduction in thickness of ferrite an d austenite bands, forming so-called pancake structure, indicate that both phases were plastically deformed during rolling of duplex steel. Deformatio n bands within the ferrite areas observed starting from 40% reduction and t he corrugated shape of ferrite-austenite pancake structure at higher degree s of deformation (above 75%) point at the macroscopic strain localization. Characteristic feature for texture development in rolled duplex steel was t he fibre character of deformation textures in both phases. The intensive de velopment of ferrite texture was observed in the course of deformation for both rolling variants. At a given deformation degree the rolling texture of ferrite in duplex steel under examination was stronger in comparison to on e-phase steels. In austenite the rolling texture was relatively weak in the whole range of deformations. From X-ray investigations it was concluded th at texture development of ferrite might be affected by the phase transforma tion (gamma --> alpha) induced by plastic deformation. In major part the or ientation relations between both phases are well described by Kurdjumow-Sac hs relationship.