预充氢对SCR焊接接头应力腐蚀敏感性影响  

The influence of hydrogen pre-charging on the stress corrosion susceptibility of SCR welded joints

作　　者：肖友福 刘永贞 孙有辉 闫玉升 徐连勇[1,3] 韩永典[1,3] XIAO Youfu;LIU Yongzhen;SUN Youhui;YAN Yusheng;XU Lianyong;HAN Yongdian(School of Material Science and Engineering,Tianjin University,Tianjin,300350,China;Offshore Oil Engineering Co.,Ltd.,Tianjin,300461,China;Tianjin Key Laboratory of Modern Connection Technology,Tianjin University,Tianjin,300350,China)

机构地区：[1]天津大学,材料科学与工程学院,天津300350 [2]海洋石油工程股份有限公司,天津300461 [3]天津大学,天津市现代连接技术重点实验室,天津300350

出　　处：《焊接学报》2024年第10期19-27,共9页Transactions of The China Welding Institution

基　　金：国家自然科学基金资助项目(52275365)。

摘　　要：文中通过对X65制钢悬链线立管(steel catenary riser,SCR)焊接接头进行微观组织分析、慢应变速率拉伸试验(slow strain rate test,SSRT)及断口分析,探究预充氢对SCR应力腐蚀开裂(stress corrosion cracking,SCC)敏感性的影响.结果表明,焊接接头热影响区中,细晶热影响区(fine-grained heat-affected zone,FGHAZ)主要由细小且均匀的铁素体(ferrite,F)和珠光体(pearlite,P)组成,使该区域力学性能显著优于其他热影响区域,而粗晶热影响区(coarse-grained heat-affected zone,CGHAZ)主要包括大块的先共析铁素体(proeutectoid ferrite,PF)、M-A组元等组织,使得该处抗SCC性能较差.SSRT试样在不同预充氢时间的条件下,应力-应变曲线的弹性阶段几乎重合,但预充氢使得试样抗拉强度降低.此外,NaCl溶液腐蚀环境试样未充氢及充氢4天的应力腐蚀敏感性系数EZ分别为0.67%和11.14%;H_(2)S腐蚀环境试样未充氢及预充氢4天的应力腐蚀敏感性系数EZ值分别为11.96%和46.38%,证明两种腐蚀环境下预充氢均会降低焊接接头的抗SCC能力.试样在空气环境中发生韧性断裂,在两种腐蚀环境主要发生准解理断裂,预充氢使材料韧性降低,断口附近的微裂纹和孔洞现象加剧,降低了材料的抗SCC性能.This study shows the influence of hydrogen pre-charging on the stress corrosion cracking(SCC)susceptibility of steel catenary riser(SCR)welded joints made of X65 through microstructural analysis,slow strain rate tensile test(SSRT),and fracture surface analysis.The results reveal that the fine-grained heat-affected zone(FGHAZ)of the welded joints primarily comprises fine and uniform ferrite(F)and pearlite(P),significantly enhancing the mechanical property of this zone compared to other heat-affected zone.In contrast,the coarse-grained heat-affected zone(CGHAZ)is characterized by large block of proeutectoid ferrite(PF)and M-A constituent,resulting in poor SCC resistance in this area.Although the elastic stage of the stress-strain curve of SSRT sample under various hydrogen pre-charging time nearly coincide,hydrogen pre-charging decreases the tensile strength of the samples.Additionally,in a NaCl solution corrosion environment,the stress corrosion susceptibility coefficient EZ of the samples hydrogen uncharged and after four days of hydrogen pre-charging are 0.67%and 11.14%,respectively;in an H_(2)S corrosion environment,the stress corrosion susceptibility coefficient EZ values for the samples hydrogen uncharged and after four days of hydrogen precharging are 11.96%and 46.38%,respectively.This demonstrates that hydrogen pre-charging reduces the SCC resistance of welded joints in both corrosion environment.The samples undergo ductile fracture in the air environment,while quasi-cleavage fracture predominates in both corrosion environment.Hydrogen pre-charging reduces the material toughness and exacerbates microcracks and hole near the fracture surface,thereby reducing the material's resistance to SCC.

关 键 词：钢悬链线立管 X65钢 应力腐蚀开裂 预充氢 

分 类 号：TG442[金属学及工艺—焊接]