不同取向激光增材制造GH4169合金电子束焊接头组织和性能

对具有不同晶体取向(0°、45°和90°)的激光增材制造GH4169合金进行真空电子束对接焊接实验,分析了两侧母材不同晶体取向差情况下的焊缝金属组织和力学性能。结果表明:GH4169合金电子束焊缝组织的枝晶有明显择优取向,焊缝组织依托母材晶体连续生长,焊缝枝晶择优取向随母材晶体取向的变化而变化,0°和90°取向差焊缝组织呈从母材外延连续生长特征,而45°取向差焊缝枝晶组织出现取向转变。随两侧母材晶体取向差的增大,在焊缝中心区域和熔合线附近大角度晶界含量都呈现出先增大后减小的趋势。拉伸测试结果表明,焊接接头的抗拉强度随两侧母材晶体取向差增大而降低,分别为721.8、720.7和702 MPa,均低于母材737.2 MPa的抗拉强度。两侧母材不同取向差的焊缝区HV硬度值均在2650 MPa上下小幅波动。焊缝金属的塑性变形受焊缝各区域晶体取向影响,它的变化与大角度晶界含量有关,组织中软取向含量越多,金属组织变形量越大。焊缝中心线和熔合线在变形过程中的弯曲程度越大,焊接接头塑性越强。

Microstructure and mechanical property of electron beam welding joint of GH4169 alloy with different crystal orientations fabricated by laser additive manufacturing

In this paper, electron beam welding of laser additive manufacturing GH4169 alloy with different crystal orientation difference (0°, 45°, and 90°) were conducted, and the microstructure and mechanical properties of the weld metal under different crystal orientation of the parent metals on both sides were analyzed. The results show that the dendrites of weld structure have obvious preferential orientation, and the weld structure continuously grows based on the base metal crystal. With the increase of the crystal orientation difference (0°, 45°, and 90°), the content of the large-angle grain boundary in the central area of the weld increases first and then decreases; for the fusion line area of the weld, the content of the large-angle grain boundary increases first and then decreases from 0°, 45° and 90°. The tensile test results show that the tensile strength of the welded joint decreases as the crystal orientation difference increases, which are 721.8Mpa, 720.7Mpa, and 702Mpa respectively, and they are all lower than the base metal which has a tensile strength of 737.2MPa. The hardness values of the weld areas with different orientation difference (0°, 45° and 90°) fluctuated slightly at 265 HV. The plastic deformation of the weld metal is affected by the crystal orientation of each region of the weld. It has the same distribution trend as the large-angle grain boundary content. The more soft-oriented crystal content in the structure, the greater the amount of metal structure deformation. The greater the degree of bending, the stronger the plasticity of the welded joint.