Wang Xueli, Wang Dongpo, Deng Caiyan, Li Chengning
Key Laboratory of Advanced Joining Technology of Tianjin, Department of Materials Science and Engineering, Tianjin University, Road Weijin 92, Tianjin 300072, China.
Pipe China North Pipeline Company, Road Xinkai 408, Langfang 065000, China.
Materials (Basel). 2022 Jun 24;15(13):4458. doi: 10.3390/ma15134458.
To analyze the causes and mechanisms affecting the fracture toughness of X80 pipeline steel welded joints against HS, the fracture toughness of different zones of X80 pipeline steel welded joints in both air and saturated HS solution was investigated. The fracture toughness of welded joints degraded significantly in the saturated HS 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 HS corrosion, with the CTOD characteristic value reaching 42% of that in air. The resistance of the welded joint to HS 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 HS corrosion also reduced the fracture toughness of the welded joint.
为分析影响X80管线钢焊接接头抗硫化氢断裂韧性的原因及机制，研究了X80管线钢焊接接头在空气和饱和硫化氢溶液中不同区域的断裂韧性。焊接接头的断裂韧性在饱和硫化氢溶液中显著降低，其中粗晶热影响区（CGHAZ）和焊缝金属（WM）的裂纹尖端张开位移（CTOD）特征值分别仅为空气中的8%和12%。然而，亚临界热影响区（SCHAZ）表现出较好的抗硫化氢腐蚀性能，CTOD特征值达到空气中的42%。焊接接头的抗硫化氢腐蚀性能对微观组织敏感。焊缝金属中存在晶界铁素体（GBF），且粗晶热影响区的晶界取向角度不利于阻碍裂纹扩展。此外，硫化氢腐蚀导致的氢致裂纹的形成也降低了焊接接头的断裂韧性。
