超塑成形对GH4169合金激光焊接组织的影响

Effects of superplastic forming process on microstructure of GH4169 laser beam welds

采用激光连接/超塑成形组合技术制造了GH4169合金三层板结构件,研究了超塑成形(温度965℃,成形时间130min)对GH4169高温合金激光焊接组织的影响。试验结果表明:GH4169高温合金激光焊接组织主要由树枝晶构成,枝晶间中有Nb元素偏聚现象,即形成了一种金属间化合物Laves相;焊接组织在超塑成形后,焊缝中心出现了粗大的等轴晶粒,熔合线附近的柱状晶粒变得粗大,成形后大部分Laves相转变为δ相,但仍有少部分Laves相保留了下来;成形后焊缝的维氏硬度明显提高,由成形前的331.63HV0.1提高到391.74HV0.1,接近成形后母材的硬度415.63。超塑成形对GH4169高温合金激光焊接组织有明显的改善作用。

Three-sheet structure was fabricated by laser beam welding/superplastic forming combined technology.Effects of superplastic forming process（temperature 965℃,forming time 130min） on the microstructure of GH4169 laser beam welds were studied.Test results show that the microstructure of GH4169 laser beam welds consists of dendrites.Laves phase is precipitated in interdendrite.After superplastic forming,coarse equiaxed grains are observed in interior of the weld and columnar dendrite at the regions adjacent to the fusion boundary becomes coarser.Most of Laves phase is dissolved and turned into δ phase but a little of Laves phase remains in the fusion zone after superplastic forming. Hardness of the weld increases from 331.63HV 0.1 in as-weld condition to 391.74HV 0.1 after superplastic forming which is closed to that of the parent material after superplastic forming.Microstructure of GH4169 laser beam welds is improved obviously after superplastic forming.