双金属复合管中L360MS管线钢焊接接头的疲劳裂纹扩展行为以及疲劳寿命预测  

Fatigue Crack Propagation Behavior and Fatigue Life Prediction of L360MS Pipeline Steel Welded Joint in Bimetallic Composite Pipe

作　　者：李洋阳 王基翔 周培山[1] 徐颖超 王斌[1] LI Yangyang;WANG Jixiang;ZHOU Peishan;XU Yingchao;WANG Bin(School of New Energy and Materials,Southwest Petroleum University,Chengdu 610500,China;China Petroleum Pipeline Research Institute Co.,Ltd.,Langfang 065000,China;West-East Gas Transmission Branch,Pipe China,Shanghai 200122,China)

机构地区：[1]西南石油大学新能源与材料学院,成都610500 [2]中国石油天然气管道科学研究院有限公司,廊坊065000 [3]国家石油天然气管网集团有限公司西气东输分公司,上海200122

出　　处：《机械工程材料》2025年第3期105-113,共9页Materials For Mechanical Engineering

基　　金：四川省科技计划项目(2021YFG0364)。

摘　　要：以NiCrMo-3合金作为焊接材料,对L360MS管线钢/N08825镍基合金双金属复合管进行多层多道对接焊,剥离N08825镍基合金覆层后测试了L360MS管线钢焊接接头的硬度和拉伸性能。参考实际运行条件,对L360MS管线钢焊接接头进行疲劳裂纹扩展试验,采用柔度法获得不同区域的裂纹长度-循环次数曲线,基于Paris公式研究不同区域的疲劳裂纹扩展行为,并对疲劳寿命进行预测。结果表明:拉伸试验后,接头试样在母材处断裂,焊缝呈高强匹配状态;焊缝硬度在220~250 HV,明显高于母材(170~185 HV),最高值出现在邻近熔合线焊缝区域,最低值出现在热影响区。母材、热影响区和焊缝中的疲劳裂纹主要以沿晶和穿晶方式扩展,但焊缝中疲劳裂纹扩展路径更加曲折,并伴有分叉现象,甚至出现环形裂纹。热影响区的Paris材料常数C最大,母材次之,焊缝最小,在应力比0.1下母材和热影响区的疲劳裂纹扩展速率较快,焊缝区域最慢。对材料常数C修正后,得到疲劳裂纹沿深度方向扩展的寿命预测公式,预测得到内部存在沿管体周向的半椭圆裂纹的管道热影响区的疲劳寿命最短,该区域是焊接接头疲劳性能最薄弱的区域。Multi-layer and multi-pass butt welding of L360MS pipeline steel/N08825 nickel-based alloy bimetallic composite pipe was carried out by using NiCrMo-3 alloy as welding material.The hardness and tensile properties of welded joint of L360MS pipeline steel after stripping N08825 nickel-based alloy coating were measured.The fatigue crack propagation test according to the actual operating conditions was carried out on welded joints of L360MS pipeline steel.The crack length-cycle number curves in different regions were obtained by using the flexibility method.The fatigue crack propagation behavior in different regions was studied on the basis of caculation of the Paris formula,and the fatigue life was predicted.The results show that after tensile test,the joint specimen was fractured at base metal,and the weld was in a high-strength matching state.The hardness of the weld was in the range of 220‒250 HV,which was significantly higher than that of the base metal(170‒185 HV).The highest hardness appeared in the weld area adjacent to the fusion line,and the lowest hardness appeared in the heat affected zone.The fatigue cracks in the base metal,heat affected zone and weld mainly propagated in intergranular and transgranular modes.However,the fatigue crack propagation path in the weld was more tortuous,accompanied by bifurcation and even annular cracks.The Paris material constant C of the heat affected zone was the largest,followed by the base metal,and that of the weld was the smallest.Under the stress ratio of 0.1,the fatigue crack propagation rates of the base metal and the heat affected zone were faster,and that of the weld was the slowest.After modifying the material constant C,the life prediction formula of fatigue crack propagation along the depth direction was obtained.It was predicted that the fatigue life of the heat-affected zone of the pipe with semi-elliptical cracks along the circumference of the pipe body was the shortest,and the heat-affected zone was the weakest area of the fatigue performance of the wel

关 键 词：L360MS管线钢 焊接接头 疲劳裂纹扩展 疲劳寿命 

分 类 号：TG405[金属学及工艺—焊接]