Effect of Pre-quenching Temperature on Microstructure and Mechanical Properties of a Low-Alloyed TRIP-Aided Steel

Different pre-quenching + two-stage heat treatments were conducted on a low-alloyed transformation-induced plasticity (TRIP)-aided steel. The results showed that combining pre-quenching with conventional two-stage heat treatment can refine the ferrite grains effectively and improve the mechanical properties of the experimental TRIP-aided steel. Simultaneously, it is beneficial to obtain granular, small blocky, lath-like, and film-like retained austenite (RA). With the pre-quenching temperature increasing from 0 to 900 °C, the average grain size of ferrite and RA decreased from 2.4 to 1.3 μm and 0.43 to 0.36 μm, respectively. Combined pre-quenching at 875 °C for 2 min with two-stage heat treatment, the investigated steel exhibited an outstanding combination of ultimate tensile strength (UTS) of 842 MPa, total elongation (TEL) of 32.5%, and UTS × TEL of 27.4 GPa % because of the grain refinement and sustained TRIP effect.