| 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. |
PDF Full Text Request