Effect of H2S Corrosion on the Fracture Toughness of the X80 Pipeline Steel Welded Joint |
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| Authors: | Xueli Wang Dongpo Wang Caiyan Deng Chengning Li |
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| Affiliation: | 1.Key Laboratory of Advanced Joining Technology of Tianjin, Department of Materials Science and Engineering, Tianjin University, Road Weijin 92, Tianjin 300072, China; (X.W.); (C.D.); (C.L.);2.Pipe China North Pipeline Company, Road Xinkai 408, Langfang 065000, China |
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| Abstract: | To analyze the causes and mechanisms affecting the fracture toughness of X80 pipeline steel welded joints against H2S, the fracture toughness of different zones of X80 pipeline steel welded joints in both air and saturated H2S solution was investigated. The fracture toughness of welded joints degraded significantly in the saturated H2S solution, where the crack tip opening displacement (CTOD) characteristic value in the coarse grain heat-affected zone (CGHAZ) and weld metal (WM) was only 8% and 12% of that in air, respectively. However, the sub-critical grain heat-affected zone (SCHAZ) showed better resistance to H2S corrosion, with the CTOD characteristic value reaching 42% of that in air. The resistance of the welded joint to H2S corrosion was sensitive to microstructures. The grain boundary ferrite (GBF) presented in WM, and the angle of grain boundary orientation in CGHAZ was not conducive to hindering crack propagation. Moreover, the formation of the resultant hydrogen cracks owing to the H2S corrosion also reduced the fracture toughness of the welded joint. |
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| Keywords: | hydrogen sulfide pipeline steel fracture toughness coarse grain heat-affected zone subcritical grain heat-affected zone |
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