23Cr-14Ni高氮奥氏体不锈钢σ相析出行为EI北大核心CSCD

采用经验公式、热力学计算方法、Gleeble热/力模拟实验技术,结合光学显微镜、扫描电镜及透射电镜分析,研究了23Cr-14Ni高氮奥氏体不锈钢中σ相的析出行为。结果表明,23Cr-14Ni高氮奥氏体不锈钢中σ相可在960~1030℃析出,高于1050℃溶解。σ相析出具有异常快速的动力学特征,在经过1030℃保温1 min固溶处理后,σ相可直接从奥氏体晶界快速析出,析出先于碳氮化物相。σ相析出动力学行为及相对碳氮化物的析出次序和传统奥氏体不锈钢显著不同。铬、锰、钼元素含量较高且钼元素在晶界处偏聚提高了σ相平衡析出温度,是加速σ相析出的主要原因。

Precipitation behavior of σ phase in 23Cr-14Ni high-nitrogen austenitic stainless steel

Precipitation behavior of σ phase in 23Cr-14Ni high-nitrogen austenitic stainless steel was investigated by empirical formulas, thermodynamic calculations, Gleeble thermo-mechanical simulation, optical microscope, scanning electron microscopy and transmission electron microscopy analysis. Results show that the σ phase in 23Cr-14Ni high nitrogen austenitic stainless steel can be precipitated at 960-1030℃ and dissolved above 1050℃. The σ phase shows unusually rapid precipitation kinetic behavior, which can directly precipitate from austenite grain boundary after solution-treated at 1030℃ for 1 min and precipitate prior to carbonitride. The kinetics and the σ phase precipitation sequence comparing to carbonitride are significantly different from that of traditional austenitic stainless steels. The increase of σ phase equilibrium precipitating temperature due to the high contents of Cr, Mn and Mo elements as well as the segregation of Mo on grain boundary, is the main reason for the acceleration of σ phase precipitation.