Effects of Si addition on microstructure and properties of martensitic stainless steel treated by quenching and partitioning process

Abstract

In order to improve the strength-plasticity and corrosion resistance, two nitrogen-alloyed martensitic stainless steels 10Cr13N and 10Cr13Si2N with different Si contents were designed and fabricated. The experimental steels were subjected to a quenching-partitioning (Q&P) process with constant quenching finish temperature and partitioning temperature but changing partitioning time.The effect and mechanism of Si addition were investigated from the changes of microstructure and mechanical properties. The results show that lath martensite and retained austenite can be obtained through quenching and partitioning process, and its strength-plasticity is significantly higher than that of quenching and tempering. As the partitioning time prolongs, the volume fractions of retained austenite in microstructures of two steels increase to a maximum first and then decrease gradually, which has slight effect on strength, but significant effect on elongation. Increasing Si content in steel is beneficial to inhibit the precipitation of carbonitride in martensite and improve the volume fraction and stability of retained austenite, it can significantly improve the deformability of steel but reduce the impact toughness slightly.

Keywords

• martensitic stainless steel
• q&p
• silicon
• retained austenite
• strength-plasticity