针对Ti17合金锻件小尺寸表面缺陷进行了激光修复,研究了修复过程中的显微组织演化规律,测试了沉积区、热影响区和基材区的显微硬度分布,并对比分析了激光修复试样与锻件试样的室温拉伸性能.结果表明:在激光沉积区内,从界面处外延生长的β柱状晶晶界模糊,相邻的晶粒难以区分,晶内为快速凝固细小的树枝晶亚结构,未见α相析出;基材区为等轴α和β转变组织构成的双态组织;热影响区内原针状α板条和次生α相长大粗化.显微硬度测试结果表明,未见α相析出的沉积区显微硬度最低,基材区最高,热影响区显微硬度处于中间过渡分布状态.拉伸结果表明,激光修复试样强度高于锻件,而塑性指标低于后者.

In this paper,the wrought TC17 titanium alloys with small defect on the surface had been repaired by laser.The microstructure evolution and the microhardness distribution in the laser deposited zone(LDZ)、heat affected zone(HAZ)and the substrate zone(Substrate)were investigated comparatively.The results show that:the grain boundaries is blurred in the LDZ with the epitaxial growth of β columnar crystal,neighboring gain is difficult to distinguish and the microstructure is small dendrites structure with rapid solidifition without alpha phase precipitation.The wrought substrate is composed of duplex microstructure.The HAZ experience a continuous microstructural transition from the SZ to the LDZ.Microhardness test results show that:the microhardness of LDZ without α phase is lowest,that of SZ is highest,and that of HAZ presents middle transition state.Tensile results show that the strength of laser repaired specimen is higher than that of forgings,but the plasticity is lower than the latter.