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利用光学显微镜、扫描电镜及透射电镜,结合Thermo-Calc热力学分析,研究了铌稳定化0Cr19Ni15Mn5Mo2NbN奥氏体不锈钢铸钢晶界处高温相析出行为及其对力学性能的影响。结果表明,0Cr19Ni15Mn5Mo2NbN钢晶界处存在Nb Cr(CN)、Nb(CN)2种大尺寸高温析出相,均为凝固末期液析形成。在铌含量确定条件下,这2种大尺寸晶界析出相在凝固末期的竞争析出行为受碳含量的影响。碳含量存在临界成分,碳含量低于临界成分时,Nb Cr(CN)首先液析形成;碳含量高于临界成分时,Nb(CN)首先液析形成。液析形成的NbCr(CN)热稳定性较高,1 050℃固溶处理无法使之完全溶入奥氏体。沿晶界分布的大尺寸析出相,对0Cr19Ni15Mn5Mo2NbN铸钢固溶热处理后的塑性及冲击韧性损害较大。
The precipitation behavior of high temperature phase in the grain boundary of 0Cr19Ni15Mn5Mo2NbN austenitic stainless steel with niobium stabilization and its effect on mechanical properties were studied by optical microscope, scanning electron microscope and transmission electron microscope combined with Thermo-Calc thermodynamic analysis. The results show that NbCr (CN) and Nb (CN) have two kinds of large-size high-temperature precipitates in the grain boundaries of 0Cr19Ni15Mn5Mo2NbN steel. Under the condition of niobium content, the competitive precipitation behavior of the two large grain boundary precipitates during the final solidification stage is affected by the carbon content. When the carbon content is lower than the critical component, Nb Cr (CN) is firstly liquid-formed. When the carbon content is higher than the critical component, Nb (CN) is firstly liquid-formed. The hydrothermal stability of NbCr (CN) formed by liquid chromatography is high, and the solution treatment at 1 050 ℃ can not completely dissolve into austenite. Along the grain boundary distribution of large-size precipitates, 0Cr19Ni15Mn5Mo2NbN cast steel solution heat treatment ductile plasticity and impact toughness.