Advantages of intercritically annealed quenching and partitioning (IQ&P) process in 4Mn steel

Abstract

For 4Mn steel, the deterioration of austenite stability caused by insufficient Mn content and the neglect of strength in intercritical annealing (IA) process are the main reasons limiting its application. In this study, based on the IA and quenching + partitioning (Q&P) process, a more suitable intercritically annealed quenching and partitioning (IQ&P) process for 4Mn steel was proposed. It is found that the IQ&P process can combine the advantages of IA and Q&P, and can obtain more austenite with sufficient stability by using quenching + partitioning process while maintaining ultra-fine grain size. While maintaining high plasticity (total elongation: 23.4%), the ultimate tensile strength of 4Mn steel is increased to more than 1200 MPa with the Lüders effect eliminated.

Keywords

• 4Mn steel
• Intercritically annealed quenching and partitioning process
• Retained austenite
• Higher strength
• Lüders effect