HOT AND COLD-ROLLING OF HIGH-NITROGEN CR-NI AND CR-MN AUSTENITIC STAINLESS-STEELS

Behavior of austenitic Cr-Ni-(0.14-0.50)N and Cr-Mn-(0.78-1.00)N steel s in hot and cold rolling was investigated by rolling experiments and mechanical testing. Structure of the steels in the as-cast condition a nd fracture surfaces after the rolling experiments were investigated u sing optical and scanning electron microscopy (SEM). Resistance to def ormation was calculated using rolling forces in hot rolling. Increase in strength in the rolling experiments was related to the nitrogen con tent of the steels. Resistance to deformation during hot rolling incre ased with decreasing rolling temperature and with increasing nitrogen content. In some steels, hot rolling led to edge cracking, which was m ore a function of impurity than nitrogen content. Microscopy revealed that the edge cracking occurred along grain boundaries and second phas e particles. For the cold-rolled steels, the highest achievable reduct ions were limited due to a ''crocodiling'' phenomenon, that is, openin g of the strip end. Fracture type at the opened strip end was a brittl e-like fracture.