X90管线钢管埋弧焊缝组织与性能分析  

Impact toughness of base metal and welded joints of X90 high-strength pipeline steel

作　　者：毕宗岳 杨军[1,2] 牛辉 黄晓江[1,2] BI Zongyue;YANG Jun;NIU Hui;HUANG Xiaojiang(National Engineering Technology Research Center for Petroleum and Natural Gas Tubular Goods,Baoji 721008,China;Steel Pipe Research Institute of Baoji Petroleum Steel Pipe Co.,Ltd.,Baoji 721008,China)

机构地区：[1]国家石油天然气管材工程技术研究中心,宝鸡721008 [2]宝鸡石油钢管有限责任公司钢管研究院,宝鸡721008

出　　处：《焊接学报》2018年第10期35-40,130,共7页Transactions of The China Welding Institution

基　　金：国家重点研发计划项目(2018YFC0310300)

摘　　要：X90管线钢管是目前正在研究开发的一种新型高强度管线钢管.随着管材强度的提高,焊缝的组织与性能成为研究与控制的关键.文中对焊缝、热影响区(HAZ)和母材微观组织、晶粒取向、大/小角度晶界占比及冲击断口形貌等进行了分析研究.结果表明,焊缝试样近断口区组织为针状铁素体(AF)+准多边形铁素体(QPF),M-A组元呈楔形、块状和条带状,分布于相界处,尺寸较大,长1.8μm,宽0.5μm,组织有效平均晶粒尺寸为3.12μm,大角度晶界比例为67.15%;而HAZ试样近断口区组织为粒状贝氏体(GB)+多形态M-A组元,晶粒粗大,M-A组元多以条带状、楔形分布于晶界和晶内,组织有效平均晶粒尺寸为4.52μm,大角度晶界比例为85.95%.母材试样近断口区组织是以细小AF+QPF+板条贝氏体(LB)+少量M-A组元为主的多相匹配的复相组织,M-A组元尺寸细小,组织有效平均晶粒尺寸为2.1μm,大角度晶界比例为93.75%.密集分布的大尺寸M-A组元和大角晶界占比较小是导致焊缝冲击韧性低于母材的重要原因.X90 pipeline steel pipe is a new type of high strength pipeline steel pipe being researched and developed.With the increase of pipe strength,the structure and properties of submerged arc welding seam become the key of research and control.The impact toughness in low temperature,fracture morphology,microstructure characteristics,grain orientation and percentage of large/small angle grain boundaries of weld seam,heat affected zone(HAZ)and base metal in X90 steel grade spiral submerged arc welded pipe manufacture were investigated by OM,SEM,TEM,EBSD and Charpy impact experiments.The results indicate that the microstructure near fracture zone of weld seam specimen was composed of acicular ferrite(AF)and quasi-polygonal ferrite(QPF).The form of MA constituents shows diversity,sharp-angled clearly and the size increased as length×width=1.8μm×0.5μm.The values of average grain size was 3.12μm and the proportion of largeangle grain boundaries was 67.15%.The microstructure near fracture zone of HAZ specimen was composed of granular bainite(GB)and multi-morphological M-A constituents,the M-A constituents in the grain boundary and crystal.The values of average grain size was 4.52μm and the proportion of largeangle grain boundaries was 85.95%.The microstructure near fracture zone of base metal specimen was composed of fine AF,fine QPF,lath bainite(LB)and a small fine granular M-A(martenite/austenite)structure.The values of average grain size was 2.1μm and the proportion of large-angle grain boundaries was 93.75%.Concentrated distribution of large size M-A constituents and the relatively small proportion of large-angle grain boundaries were the main reason for the poor impact toughness of weld.

关 键 词：X90管线钢 冲击韧性 焊接接头 针状铁素体 

分 类 号：TG401[金属学及工艺—焊接]