Improvement of tensile mechanical properties in a TRIP-assisted steel by controlling of crystallographic orientation via HSQ&P processes

The mechanical properties and grain orientation evolution have been investigated in a TRIP-assisted steel in search of enhanced strength and plasticity. A novel combined process (HSQ&P) of Hot Stamping (HS) and Quenching and Partitioning (Q&P) treatment with different initial straining temperatures has been conducted by thermo-mechanical simulation. The microstructure was analyzed in detail using scanning electron microscopy and electron backscattered diffraction. The results revealed that carbon partitioning from saturated martensite into retained austenite led to less distortion in the lattice due to less martensite tetragonality, which decreases stored energy. In addition, the predominance of {011} and {111} crystallographic textures, which are parallel to the normal direction of retained austenite and martensite grains formed in HSQ&P sample, enhanced ductility as it facilitates displacive phase transformation. Thus, it improves the tensile mechanical properties as verified by subsized tensile test. A novel thermo-mechanical process is being proposed for TRIP-assisted steels Based on these findings.