GH2132合金环缝结构件裂纹敏感性研究
Crack sensitivity of circumferential weld structure for superalloy GH2132
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摘要: 针对轴承座底盘与螺柱TIG焊环缝结构,对不同硼含量的GH2132合金进行焊接工艺试验,检测焊接接头表面及横截面裂纹,结合接头显微组织形貌及XRD残余应力测试结果分析裂纹形成机理。结果表明,GH2132合金底盘与螺柱TIG焊接头具有焊接裂纹敏感性,裂纹出现在熔合线附近的粗晶区,沿晶界向母材扩展,为液化裂纹。焊接接头裂纹敏感性随焊接热输入的增大而增大,合金中硼元素含量对液化裂纹敏感性有较大影响,含硼高的合金裂纹敏感性高于含硼低的合金。焊接接头裂纹的分布与该构件结构特征密切相关。由于轴承座底盘有一个中心孔且螺柱靠近中心孔的边缘,焊接时螺柱外侧焊缝受到的拘束应力大于其内侧焊缝,裂纹多出现在螺柱环形焊缝的外侧。Abstract: The TIG welding process tests of the circumferential weld between the bearing disk and the stud made of superalloy GH2132 with different boron content were carried out. The crack rates in the weld on the surface and cross-section of the weld were measured. The mechanism of weld crack was analyzed based on the microstructure and XRD measured residual stresses. The results shown that welding crack sensitivity exists in TIG welded joints of GH2132 alloy. The cracks appear in the coarse grain zone near the fusion line of the weld, and spread to the base metal along the grain boundary, which belong to liquation crack. The crack sensitivity rises with the increase of the heat input. The content of boron in the alloy has a significant influence on the sensitivity of the liquation cracking. The higher the boron content in the alloy, the higher the crack sensitivity. The location of the crack in the circumferential weld is related to the structural characteristics of the component. If the disk has a circular hole in its center and the stud on the plane of the disk is close to the hole, the crack appears in the outer side of the circumferential weld of the stud, due to the fact that the stress of the weld outside of stud is higher than that in the weld inside of the stud during welding.