The effect of molybdenum in silicon-manganese-niobium TRIP steels.

摘要

ThermoMechanical Processing (TMP) is a tool whereby a controlled microstructure and mechanical properties are achieved by a combination of controlled deformation and heat treatment steps. However, because there exists a trade off between strength and ductility, steels destined for both high formability and high strength applications must further undergo a sequence of energy intensive heat treatment steps. Alternatively, TRIP (TRansformation Induced Plasticity) steels have been acknowledged to possess excellent combinations of both strength and ductility. The timely strain or stress induced transformation of Retained Austenite (RA) to martensite locally strengthens these steels at the point of plastic instability, causing failure by necking to be postponed and shifted elsewhere along the steel. This phenomenon repeated over and over again allows increased levels of deformation, prior to fracture.;In the current TRIP grades, Si is a key elemental addition. However, in levels exceeding 1.0 wt.%, it is unpopular as it is responsible for a tenacious oxide layer. In this work, it is suggested that Mo may potentially replace Si in part.;Multi pass rolling simulations were also performed using torsion. (Abstract shortened by UMI.).