DH36钢水下摩擦叠焊接头组织性能分析

Microstructures and mechanical properties of underwater friction stitch weld of DH36 steel

采用天津大学自主研制的摩擦叠焊设备进行了DH36钢水下摩擦叠焊试验,对摩擦叠焊接头进行了显微组织观察和硬度测试,对比分析了不同焊接压力和不同焊接环境(水下和空气)下接头不同位置的拉伸性能.结果表明,水下摩擦叠焊接头不同部位显微组织与硬度均存在较大差异,焊缝区组织以板条马氏体和条状及粒状贝氏体为主,硬度最高值为489.3 HV10,焊缝上部区域硬度值略高于下部,中间单元焊缝(后焊)硬度值整体上高于两侧单元焊缝(先焊);焊接压力增加能一定程度改善接头连接质量;空气中焊接的试件平均抗拉强度高于水中焊接接头.

Using the hydraulically powered welding equipment developed by Tianjin University,underwater friction stitch welding of DH36 steel was conducted.The microstructures and mechanical properties (hardness and tensile property) of the weld have been investigated.The microstructure of the weld and the hardness distribution were heterogeneous.The overall microstructure of the weld metal consisted of a volume of lath martensite and bainite.The highest hardness value was 489.3 HV10,which located at the upper part of friction stitch weld.The hardness levels of the upper region of the stitch weld were higher than those of the lower region,and hardness levels of the last weld in the stitch sequence were higher than those of the first two welds.Stitch welds with higher welding axis forces showed better ultimate tensile strength than those with lower ones when the other conditions kept constant.And the tensile strength of welds in air was better than that of welds in water.