不锈钢拦污栅栅条断裂失效的原因

摘要

The reasons for the fracture failure of trash rack paling were analyzed by metallographic examination,scanning electron microscopy (SEM) observation,chemical composition analysis and mechanical property testing.The results show that the corrosion resistance of the fractured paling was decreased due to the low content of Cr and Ni.The fractured paling was subjected to stress during service.And S2-,Cl-and other corrosive ions in environment gathered in the metal surface,destroyed the passive film on the surface of metal.Stress corrosion cracking occurred in the paling under the combined effect of corrosive ions and stress.%通过金相检验、扫描电子显微镜观察以及化学成分分析和力学性能测试等方法对拦污栅栅条断裂失效的原因进行了分析.结果表明:一方面,断裂栅条中Cr、Ni含量偏低降低了不锈钢的耐蚀性;另一方面,该栅条曾在服役过程中受到应力作用,且环境中的S2-和Cl-等腐蚀性离子聚集在金属表面,破坏了其表面钝化膜,在腐蚀性离子和应力的共同作用下栅条发生应力腐蚀开裂.