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通过微观组织分析、力学性能测试及微区成分能谱分析等方法,研究了过热蒸汽管道裂纹产生的原因,进行了热处理工艺重现试验,以及重现后的微观组织观察、晶粒尺寸统计、力学性能分析等研究。试验结果表明:管壁处裂纹的产生是发生了应力腐蚀,且裂纹被逐渐加宽形成分枝;Cr、Mo碳化物沿晶界析出并在晶界处连续分布,破环了晶界的结合;同时使得基体内Cr元素的贫化,晶界与基体腐蚀电位发生变化,加速应力腐蚀的发生。进行了热处理工艺重现试验后,其综合性能性能均优于原送检样。
The causes of cracks in superheated steam pipelines were studied by means of microstructure analysis, mechanical property test and energy spectrum analysis of micro-area components. The heat treatment process reappearance test was carried out, and the microstructure observation, grain size statistics, Mechanical properties analysis and other research. The experimental results show that the crack at the pipe wall is stress corrosion, and the cracks are gradually broadened to form branches. The Cr and Mo carbides are precipitated along the grain boundaries and are continuously distributed at the grain boundaries, breaking the combination of the grain boundaries ; At the same time make the Cr depletion of the matrix, the grain boundary and the substrate corrosion potential changes, accelerating the occurrence of stress corrosion. After the heat treatment process to reproduce the test, its overall performance is better than the original performance of the original sample.