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对含铌及Nb-Ti铁素体不锈钢进行固溶和高温时效处理,采用高温拉伸试验对其进行高温力学测试。结果表明:随着时效时间的延长,铌钢高温屈服强度降低较快,而Nb-Ti钢高温屈服强度变化不大。采用相分析、扫描电镜、透射电镜对固溶铌及微观结构进行分析,发现时效过程中固溶铌含量均降低,含铌及Nb-Ti钢500h时效后固溶铌相差不大,铌钢中析出相主要是NbN相和M6C相(Fe3Nb3C),Ti-Nb钢主要析出相是NbTi(C,N)相和Laves相(Fe2Nb)。长时间时效后,M6C相和Laves相严重粗化且分布变化明显。M6C相粗化后观察不到沿晶界连续分布,而Laves相粗化后主要在晶界连续分布,起到强化晶界的作用。
The niobium-containing and Nb-Ti ferritic stainless steels were solution-treated and aged at high temperature. High-temperature tensile tests were carried out to investigate the high-temperature mechanical tests. The results show that as the aging time increases, the yield strength of Nb steel decreases rapidly at high temperature, while the yield strength of Nb-Ti steel does not change much at high temperature. The solid solution niobium and microstructure were analyzed by phase analysis, scanning electron microscopy and transmission electron microscopy. It was found that the content of dissolved niobium in the aging process decreased. The content of niobium and niobium in Nb-Ti and Nb-Ti steels were similar after 500h aging. The main precipitates are NbN phase and M6C phase (Fe3Nb3C). The main precipitates of Ti-Nb steel are NbTi (C, N) phase and Laves phase (Fe2Nb). After aging for a long time, the phases of M6C and Laves were coarsely roughened and the distribution changed obviously. After the coarsening of the M6C phase, no continuous distribution along the grain boundary was observed. However, the coarsening of the Laves phase mainly distributes continuously in the grain boundary and plays a role of strengthening the grain boundary.