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    船用高强钢薄板FAB法埋弧焊接头显微组织与残余应力变形

    Microstructure and residual stress deformation of FAB submerged arc welding joints of high-strength steel sheets for ships

    • 摘要: 采用有限元软件对高强钢薄板FAB法埋弧焊焊接过程进行数值模拟,对试板焊接接头进行低倍检验、金相检验、硬度测试和X射线残余应力测试。结果表明:FAB法埋弧焊仿真模拟试样呈现中部下凹和横向收缩的现象,最大下凹量和收缩量分别为0.61 mm和0.52 mm;焊接接头宏观成型良好,表面粗晶区宽度约为1 mm,组织晶粒有所增大,细晶区及不完全重结晶区宽度约为1.5 mm,以细小的铁素体和珠光体带状组织为主,组织位错密度降低,硬度略有下降;焊接残余应力分布特征表现为焊缝中心区域存在较大的拉应力,其数值沿焊缝两侧呈递减趋势,热影响区则以压应力为主;焊缝区最大拉应力达到187 MPa,而热影响区最大压应力为-180 MPa,二者均显著低于材料的屈服强度极限。

       

      Abstract: The finite element software was used to simulate the FAB submerged arc welding process of high strength steel sheets. The macroscopic test, metallographic examination, hardness test and X-ray residual stress test were carried out on the welded joints of the test plate. The results show that the FAB submerged arc welding simulation specimen showed the phenomenon of central concave and transverse shrinkage, and the maximum concave and shrinkage were 0.61 mm and 0.52 mm, respectively. The macroscopic forming of the welded joint was good. The width of the coarse grain zone on the surface was about 1 mm, and the grain size of the microstructure was increased. The width of the fine grain zone and the incomplete recrystallization zone was about 1.5 mm, which was mainly composed of fine ferrite and pearlite banded structure. The dislocation density of the structure decreased and the hardness decreased slightly. The distribution characteristics of welding residual stress showed that there was a large tensile stress in the central area of the weld, and its value decreased along both sides of the weld, while the heat affected zone was dominated by compressive stress. The maximum tensile stress in the weld zone reached 187 MPa, while the maximum compressive stress in the heat affected zone was −180 MPa, both of which were significantly lower than the yield strength limit of the material.

       

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