Effect of Nb, Ti and cold deformation on microstructure and mechanical properties of austenitic stainless steels

摘要

It is well known that Nb and Ti are used to prevent sensitization in stainless steel. However, the amounts of Nb and Ti of standard are not enough to prevent completely this phenomenon. Therefore in this paper, several austenitic stainless steel heats were alloyed with different contents of Nb and Ti then cast in sand mould using an open air-induction melting furnace. The Nb content which used in this paper (more than standard values) is ranging from 0.004 to 0.410wt% and Ti content is ranging from 0.007 to 1.10wt%. The cast ingots were homogenized at 1200 ℃ and water quenched. The materials were austenitized at 1200 ℃ and then hot forged up to 85% in cross-sectional area. Solution treatment was carried out at temperatures above 1150℃ to ensure dissolution of carbides and rapid quenching to a temperature lower than the precipitation range of 875-425 ℃ was done. The cold rolling, welding and sensitization tests, EDS-SEM investigations, XRD pattern and corrosion resistance were carried out to study the effect of alloying elements (Nb and Ti) on sensitization behavior and mechanical properties.