摘要
为探究应变时效对高应变管线钢焊接接头的影响,对应变时效前后高应变管线钢焊接接头的显微组织和力学性能进行了研究.通过硬度测试、断裂韧性试验、数字图像相关(DIC)应变测试方法探究了应变时效处理前后高应变管线钢焊接接头的力学性能特点.并基于光学显微镜(OM)、扫描电子显微镜(SEM)、电子背散射衍射技术(EBSD)及X射线衍射技术分析了应变时效处理前后焊接接头的微观组织及亚结构特点.结果表明,应变时效处理后,焊接接头的显微组织未发生明显变化,但内部微裂纹数量增多,焊接接头断裂韧性呈下降趋势,且下降幅度随预应变程度的增大而增大.分析发现,位错密度增大,应变集中程度伴随几何必要位错密度的升高是导致焊接接头塑性变形能力下降,断裂韧性恶化的重要原因.
In order to explore the effect of strain aging on welded joints of high strain pipeline steel, the microstructure and mechanical properties of welded joints of high strain pipeline steel before/after strain aging were studied. The mechanical properties of welded joints before/after strain aging were investigated by hardness test, fracture toughness test and digital image correlation(DIC) strain test. The microstructure and substructure characteristics of welded joints were analyzed based on optical microscope(OM), scanning electron microscope(SEM), electron back-scattered diffraction(EBSD)technology and X-ray diffraction technology. The results indicated that the microstructure of welded joint does not change obviously after strain aging, but the inside microdefects increase. Meanwhile, the fracture toughness of welded joints decreases, and the decrease amplitude increases with the pre-strain degree. It was found that the increase of dislocation density, strain concentration as well as the geometrically necessary dislocation(GND) density are key factors leading to the decrease of plastic deformability and the deterioration of fracture toughness of welded joints.
作者
高杉杉
邸新杰
利成宁
姜圆博
李为卫
吉玲康
GAO Shanshan;DI Xinjie;LI Chengning;JIANG Yuanbo;LI Weiwei;JI Lingkang(Tianjin University,Tianjin,300350,China;CNPC Tubular Goods Research Institute,Xi'an,710077,China)
出处
《焊接学报》
EI
CAS
CSCD
北大核心
2021年第10期22-28,I0002,I0003,共9页
Transactions of The China Welding Institution
基金
国家重点研发计划(2018YFC0310305)。
关键词
应变时效
管线钢
断裂韧性
位错密度
strain aging
pipeline steel
fracture toughness
dislocation density
