焊后热处理对输送H2S介质压力管道维修焊接接头组织性能的影响
Influence of Post-weld Heat Treatment on Microstructure and Properties of Welded Joints for H2S Medium Pressure Transmission Pipeline in Repairing
周 勇， 王洪铎， 彭 涛， 吴 伟
点击：4846次 下载：0次
作者单位：西安石油大学 材料科学与工程学院，陕西 西安 710065
中文关键字：H2S介质；压力管道；焊后热处理；显微组织；性能
英文关键字： H2S medium; pressure pipeline; post-weld heat treatment; microstructure; property
中文摘要：采用手工钨极氩弧焊（TIG焊）打底，焊条电弧焊（SMAW）填充、盖面的焊接工艺对输送H2S介质压力管道（20钢）进行维修焊接，并对其焊接接头进行720～750℃下保温1 h的焊后热处理。对热处理前、后焊接接头组织和性能进行分析研究，结果表明：720～750 ℃ × 1 h热处理使焊缝区与热影响区成针状分布的魏氏组织铁素体晶粒得到细化，并使其呈退化形态；焊缝区、热影响区与母材的显微硬度整体呈下降趋势；焊接接头抗拉强度大幅度提高，断裂均处在远离焊缝的母材上。焊后热处理有效地降低了焊接接头的残余应力，改变了残余应力的分布特征，使其分布趋于“均匀”，拉应力大幅度降低。
英文摘要：The repairing of H2S medium pressure transmission pipeline(20 steel) was complemented with manual TIG（tungsten insert gas） for backing weld， SMAW (shielded metal arc welding) for filler bead and cover pass. The welded joints were treated at 720～750℃ for 1h and the microstructure and properties of welded joints with and without post-weld heat treatment (PWHT) were analyzed. The results show that the ferrite grains of needle-like widmanstatten microstructure in weld metal zone and heat affected zone are refined and their needle-like morphology is degraded after heat treatment. The microhardness of weld metal zone， HAZ and base metal decrease in totality after heat treatment. The tensile strength of welded joint is significantly improved after heat treatment and the failure occurred far away from the weld metal zone. The post-weld heat treatment can not only reduce the residual stress of welded joints but also change the distribution characteristics of residual stress and make it uniform， therefore， the tensile stress of welded joints significantly decreases.