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GH3230高温合金激光填丝焊组织和力学性能

Microstructure and mechanical properties of GH3230 superalloy laser welding with filler wire

  • 摘要: 针对在航空领域具有广泛应用前景的GH3230高温合金,开展了激光填丝焊的工艺、组织和力学性能研究,将焊缝成形、接头组织、室温拉伸性能和高温持久性能与传统钨极氩弧焊(tungsten inert gas welding, TIG)接头进行对比. 结果表明,激光填丝焊工艺可以得到成形良好的GH3230对接接头,且成形质量优于TIG接头,且更大的激光能量密度使接头 热影响区 (heat-affected zone,HAZ) 较小. 微观组织方面,较大的温度梯度和极短的熔池存续时间使焊缝组织多为树枝晶,晶间与晶内分布的析出碳化物起析出强化的作用. 力学性能方面,激光填丝焊接头的室温拉伸试样在母材(base metal,BM)断裂,而TIG接头因晶粒粗化与碳化物减少,室温拉伸性能下降,断裂位置位于焊缝区. 在高温持久性能条件下,TIG接头高温持久性能略高于激光填丝焊,两者均高于BM;弯曲试验中激光填丝焊接头与TIG接头均无裂纹缺陷,弯曲性能良好.

     

    Abstract: GH3230 superalloy has broad application prospects in the aviation field. The process, microstructure, and mechanical properties of laser welding with filler wire were investigated, and the weld formation, joint microstructure, room temperature tensile properties, and high-temperature endurance performance were compared with those of traditional tungsten inert gas welding (TIG) joints. The results have shown that the GH3230 butt joint with good shape can be obtained by the laser welding process with filler wire. The formation quality is better than TIG joints. As the energy density of the laser becomes larger, the heat-affected zone (HAZ) of joints is smaller. In terms of microstructure, the large temperature gradient and short duration of the molten pool lead to a weld microstructure mainly composed of dendrite crystals. The precipitation carbides that distribute between and within the grains contribute to precipitation strengthening. In terms of mechanical properties, the room temperature tensile specimens of joints by laser welding with filler wire fracture at base metal (BM), while TIG joints experience a decrease in room temperature tensile properties due to grain coarsening and reduction of carbides, resulting in fracture at the weld seam. Under high-temperature conditions, the high-temperature endurance performance of TIG joints is slightly higher than that of laser welding with filler wire, and both are higher than that of the BM. In the bending test, both joints by laser welding with filler wire and TIG joints show no crack defects and exhibit reliable bending performance.

     

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