热处理对选区激光熔化GH3536合金晶界与拉伸行为的影响

Effect of Heat Treatment on Grain Boundary and Tensile Behavior of Selective Laser Melting GH3536 Alloy

摘要:

采用选区激光熔化制备了GH3536合金,并分别进行固溶处理和热等静压处理,研究不同热处理手段对GH3536合金的组织形貌、晶界形态及室温拉伸行为的影响。结果表明：沉积态试样的组织由超细柱状亚晶粒与熔池界组成,存在气孔与微裂纹等缺陷；分别经固溶处理和热等静压处理后,二者致密度上升,组织转变为由大小不等的等轴晶粒交替分布组成,但后者沿晶界析出M₂₃C₆相,形成锯齿状的弯曲晶界；沉积态试样的拉伸性能表现出各向异性的特点,固溶处理可消除拉伸性能的各向异性,但抗拉强度和屈服强度均有下降,延伸率明显上升。热等静压态试样与固溶态试样相类似,但其抗拉强度、屈服强度和延伸率均有进一步的提高；三种合金的断裂机制均为微孔聚集型的韧性断裂。

关键词:GH3536;激光选区熔化;显微组织;晶界;力学性能

Abstract:

The GH3536 alloy was prepared by selective laser melting, and was subjected to solution treatment and hot isostatic pressing, respectively. The effects of different heat treatment methods on the microstructure, grain boundary morphology and room temperature tensile behavior of GH3536 alloy were studied. The results show that the microstructure of the SLM sample consists of ultra-fine columnar sub-grains and pool boundary, with defects such as pores and microcracks. The relative density of the alloy increases after solution treatment and hot isostatic pressing, respectively, and the microstructures of the two alloys consist of alternating equiaxed grains of different sizes. However, the HIP sample precipitated the M₂₃C₆ phase along the grain boundary, forming a serrated grain boundary. The tensile properties of the SLM samples show obvious anisotropy. The solution treatment can eliminate the anisotropy of the tensile properties of the sample, but the ultimate tensile strength and yield strength are reduced, and the elongation is significantly increased. The HIP sample is similar to the solid solution sample, but its ultimate tensile strength, yield strength and elongation are further improved. Tensile fracture mechanisms of all three alloys are microporous aggregate-type ductile fracture.

Key words:GH3536 alloy; Selective laser melting; Microstructure; Grain Boundary; Mechanical Properties