Optimization of Mechanical Properties of High Strength TRIP Steels

Abstract

Traditional TRIP steels have been developed for several decades, however, when thestrength reaches 1000MPa, the elongation rate is difficult to be raised over 20%. In the light ofthermodynamics, phase diagram of TRIP steel containing rather high amount of Al is optimized andthe attractive function of Al, which largely increases carbon solubility in austenite is found. As highercarbon content leads to higher stability of austenite and better TRIP effect of TRIP steel, newcomposition of high strength TRIP steel with high amount Al is designed as well as heat treatmentprocesses. The newly developed TRIP steel exhibits superior mechanical properties and the productof its strength and plasticity is higher than 30000 MPa%, i.e., the target of the mechanical propertiesof 3th generation automotive steel.