Effect of V-Ti Addition on Microstructure Evolution and Mechanical Properties of Hot-Rolled Transformation-Induced Plasticity Steel

In order to reveal the effect of V-Ti addition on the microstructure evolution and the mechanical properties of hot-rolled transformation-induced plasticity (TRIP) steel, two steels with 0.072V-0.051Ti steel (Bear-V-Ti steel) and 0.001V-0.001Ti steel (Free-V-Ti steel) were designed, respectively, and the comparison analyses were carried out by performing thermodynamic calculation and an experiment. With the thermodynamic calculation, the critical annealing temperature of a large fraction of retained austenite (similar to 51%) obtained via solute enrichment was determined, and an optimized quenching at 650 degrees C and tempering at 200 degrees C adopted on the as-hot-rolled steel. The results show that the V-Ti TRIP steel displays more optimum mechanical stability during the tensile deformation, since the fraction and the mechanical stability of retained austenite are improved and the microstructure is also ultrarefined by V-Ti alloy precipitation. The yield strength of Bear-V-Ti steel increases from 650 to 800 MPa, and the ductility reaches 37%, showing that the comprehensive mechanical properties are greatly improved.