激光增材修复Ti17钛合金的显微组织与力学性能

摘要

Laser additive manufacturing technology with powder feeding was employed to repair wrought Ti17 titanium alloy with small surface defects. The microstructure, micro-hardness and room temperature tensile properties of laser additive repaired (LARed) specimen were investigated. The results show that, cellular substructures are observed in the laser deposited zone (LDZ), rather than the typical α laths morphology due to lack of enough subsequent thermal cycles. The cellular substructures lead to lower micro-hardness in the LDZ compared with the wrought substrate zone which consists of duplex microstructure. The tensile test results indicate that the tensile deformation process of the LARed specimen exhibits a characteristic of dramatic plastic strain heterogeneity and fracture in the laser repaired zone with a mixed dimple and cleavage mode. The tensile strength of the LARed specimen is slightly higher than that of the wrought specimen and the elongation of 11.7% is lower.%采用同步送粉激光增材制造技术修复带有小比例表面缺陷的锻造Ti17钛合金,系统研究其显微组织、显微硬度及室温拉伸性能.结果表明,和大比例体修复试样相比,小比例表面修复由于缺乏足够的后续热循环,激光沉积区没有α相析出,初始β晶内由典型凝固胞晶组织组成,从而使得激光沉积区显微硬度低于由双态组织构成的锻造基材区.拉伸测试结果表明,在拉伸过程中,激光修复试样存在显著的塑性变形不均匀性,最大应变始终偏聚于激光修复区,且最终以准解理方式断裂于修复区.激光修复试样的抗拉强度略高于锻件试样,而伸长率(11.7%)低于后者.