The Effect of Microstructure Size on Microstructure and Properties of High Boron Alloy During Quenching and Partitioning (Q&P) Process

The microstructure and mechanical properties of two high boron alloys with different austenite dendrite arm sizes, namely alloy A and alloy B, were investigated before and after being treated by the quenching and partitioning (Q&P) process. The results show that the matrix of alloys is composed of fresh martensite, secondary martensite and film-like or lath-like retained austenite (RA) after being Q&P treated. The fine martensite laths, caused by the smaller size of the dendrite arm, are able to promote the diffusion of carbon during the partitioning process, leading to the formation of RA with a smaller size and higher carbon content. The partial spheroidization of the net-like boride and the improvement of matrix toughness significantly improve the impact toughness and wear resistance of the alloys.