07MnNiCrMoVDR钢焊缝组织与低温冲击韧性分析

采用SMAW焊接工艺焊接低合金高强度07MnNiCrMoVDR钢获得焊接接头，通过焊缝显微组织观察、冲击断口分析、焊缝低温冲击试验，研究了07MnNiCrMoVDR钢焊缝组织与低温冲击韧性。结果表明，焊缝组织由沿晶界分布的先共析铁素体、晶内的针状铁素体和粒状贝氏体构成，针状铁素体以微夹杂物为核心生长。温度为－40 ℃时，不同部位焊缝冲击吸收功随试样截取深度的增大而减小；与近表面处相比，1/2厚度处焊缝冲击吸收功损失约67%，在1/4厚度处，焊缝冲击吸收功随着温度的降低而降低；焊缝的低温冲击韧性符合要求。焊缝冲击断口的表面由凹凸不平变得比较平整，断口的微观形貌由韧窝花样变成解理河流花样。

Analysis of Weld Microstructure and Low Temperature Impact Toughness of 07MnNiCrMoVDR Steel

High strength low alloy 07MnNiCrMoVDR steel was welded by using shielded metal arc welding to form welded joint, weld microstructure observation, fracture surface analysis and low temperature impact toughness were operated to research weld microstructure and low temperature impact toughness. The results showed that weld microstructure was consisted of pre-eutectic ferrite along grain boundary, intragranular acicular ferrite and granular bainite, the acicular ferrite presents redial growth by micro-inclusions. The impact absorbing energy of different weld metal site gradually declined tendency with the depth increasing, and the toughness losses were by 67% in the region of half thickness compared with that of surface location. The impact absorbing energy of weld metal gradually declined tendency with the temperature reducing in the region of a quarter of thickness, and the impact absorbing energy was up to requirements at －40 ℃;The impact fracture of weld metal characterized by concavo convex was changed into flat and smooth with the temperature decreased, and the miro-morphology of fracture was changed form the dimple pattern to rive pattern