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| Failure Mechanism of Environmental Corrosion and Fracture of Flange Connection Bolts of Low-temperature Pipelines in Coastal Launch Site |
| Received:May 03, 2021 Revised:June 03, 2021 |
| View Full Text View/Add Comment Download reader |
| DOI：10.7643/issn.1672-9242.2021.09.013 |
| KeyWord:low temperature pipeline salt spray corrosion connecting bolt stress corrosion |
| Author | Institution |
| YANG Bo |
China Wenchang Space Launch Site, Wenchang , China;Key Laboratory of Reliability Technology for Space Launch Site, Haikou , China |
| YU Shao-xing |
China Wenchang Space Launch Site, Wenchang , China;Key Laboratory of Reliability Technology for Space Launch Site, Haikou , China |
| JING Jian-xin |
China Wenchang Space Launch Site, Wenchang , China |
| ZHANG Zai-jing |
China Wenchang Space Launch Site, Wenchang , China |
| ZHANG Sheng-jin |
China Wenchang Space Launch Site, Wenchang , China |
| CHEN Ji-wei |
China Wenchang Space Launch Site, Wenchang , China |
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| Abstract: |
| This paper analyzes the failure mechanism of the environmental corrosion and fracture problem of the high- strength bolts used for the flange connection of the low-temperature pipeline at the coastal launch site, and discusses the influence factors of salt spray corrosion, stress effect, microscopic morphology, chemical composition and hardness combining the “high temperature, high humidity, high salt spray” environment and the low temperature and high pressure working conditions of the bolt. The results of the study found that:the average value of bolt microhardness (108HRB) exceeded the standard; the content of C, S, and Cr in the material was abnormal; the actual force of the bolt reached more than 60% of the allowable stress; the microstructure cracks were all typical stress corrosion cracks. The failure mechanism of bolts was:under the influence of Hainan’s “three highs” marine corrosion environment, the bolts with poor corrosion resistance initiated cracks under the action of thermal stress, resulting in stress corrosion, and expanded under the action of thermal and tensile stress, invalid due to stress corrosion cracking and bolts delay brittle fracture. Finally, corresponding improvement measures are proposed for the bolt stress corrosion mechanism. |
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