Phase Formation Mechanisms and Mechanical Properties of 15-5PH Stainless Steel
摘要
The microstructure evolution and mechanical properties of 15-5PH stainless steel were investigated under different aging temperatures and holding times. The phase formation and growth mechanisms were studied by microstructure analysis, and the mechanical properties were investigated using tensile and impact tests. The results show that NbC and MoC particles are precipitated between the martensite laths after aging, which grow larger with increasing aging time and temperature. When the aging temperature is increased to 550 °C and 580 °C, ε-Cu phases appear and distribute homogeneously in the matrix. The hardness and tensile strength of the 15-5PH decrease with increasing aging temperature, while the elongation is improved. The samples after aging at 550 °C and 580 °C possess excellent impact toughness of 225 and 223 J/cm2. The reverse transformation of martensite to austenite occurs during high-temperature aging, reducing the strength and hardness of the samples, while improving its impact toughness. However, high aging temperature leads to coarsening of NbC, MoC, and ε-Cu, resulting in a simultaneous decrease in strength and fracture toughness. The present results contribute to the practical application of high-performance 15-5PH alloys and provide a reference for the processing of other age-strengthened stainless steels.