The quenching and partitioning (Q&P) process presents an effective method for producing high-strength, formable steels by developing a microstructure of martensite and retained austenite. This research aims to enhance formability while preserving mechanical strength through Q&P treatments on three commercially produced steel grades: Si-alloyed TRIP780, 22MnB5, and 27MnCrB5. The steels underwent full austenitization followed by quenching to below the martensite start temperature Ms, with subsequent isothermal holding (one-step) or reheating to a higher temperature (two-step). For the Si-alloyed TRIP steel, the amount of retained austenite was adjustable via Q&P treatments. In contrast, for the boron steels, cementite formation at high partitioning temperatures and carbide precipitation at lower temperatures hindered the stabilization of retained austenite. The optimal combination of stable austenite, strength, and ductility for TRIP780 was achieved through two-step Q&P treatments. Meanwhile, one-step Q&P treatments enhanced the strength-ductility balance for 22MnB5 and 27MnCrB5, but two-step treatments led to significant strength loss without improving ductility. The observed ductility improvement in the boron steels without Si addition is primarily attributed to the progressive tempering of martensite during Q&P processing.
