【作者】 翟红波；

【导师】 蒋晓东；

【作者基本信息】 华东理工大学 ， 安全技术及工程， 2011， 硕士

【摘要】 本文针对上海市某石化企业检修时发现大量的不锈钢螺栓开裂现象,对不锈钢螺栓进行失效原因分析。分析结果表明不锈钢螺栓断裂的主要原因是由于螺栓含碳量偏高,过饱和的碳以化合物形式沿奥氏体晶界析出,降低了材料的耐腐蚀性；同时由于螺栓所处的大气环境中富含氯、硫等元素,长期使用中有害元素在材料表面不断富集,造成材料表面产生晶间腐蚀裂纹,在应力作用下裂纹不断扩展最终导致螺栓断裂。通过对螺栓断裂失效机理的研究,提出固溶处理、表面化学钝化和表面涂层三种防应力腐蚀的对策。在实验室条件下对螺栓材料进行固溶处理、表面化学钝化和表面涂层处理,并通过金相分析、断口形貌分析、电化学塔菲尔曲线分析、恒载荷试验和慢应变速度拉伸试验对不同处理方法的防应力腐蚀效果进行研究。试验结果表明三种方法都起到了防护效果,不同程度的降低了材料的应力腐蚀敏感性。本文最后对三种防应力腐蚀对策进行了比较,研究分析了不同处理方法的适用条件,为沿海地区石化企业不锈钢设备的腐蚀防护提供参考。更多还原

【Abstract】 The paper mainly analyzed the failure cause of austenitic stainless bolts which were founded during the overhaul of certain petrochemical company in shanghai. The results showed that stainless steel bolts fracture was primarily due to higher C content. The supersaturated carbon precipitated along the austenitic grain boundaries in the form of carbon compounds, lowering the material corrosion resistance. At the same time there was a high content of chlorine, sulfur and other elements in atmospheric environment where bolts worked, so the harmful elements enriched on the material surface during the long-term using, which resulted in intergranular corrosion cracks on surface of the material. The cracks expand continuously under the stress and lead to bolt fracture finally.According to the analysis and research of the fractured bolts failure mechanism the paper put forward three kinds of bolt SCC prevention measures such as solution treatment, surface chemical passivation disposal and surface coating disposal and studied the bolt SCC prevention results of three different kinds of measures under the laboratory conditions by ways of metallographic analysis, fracture morphology analysis, electrochemical tafel curve analysis, constant loading test and slow strain rate tensile test. The test results show that three methods have played a protective effect and lowered the SCC sensitivity with different levels of the stainless steel material.The paper finally compared with three kinds of SCC prevention measures, researched the applicable conditions of stainless steel material deal with in different ways, and offered references for the protection of stainless steel equipments in the petrochemical enterprise.更多还原