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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。
The microstructure evolution of the Ti17 alloy forgings was investigated by laser repairing. The microstructure evolution of the Ti17 alloy forgings was studied. The microhardness distribution in the deposition zone, the heat affected zone and the substrate zone was tested. Tensile properties of samples at room temperature forgings and forgings. The results show that in the laser deposition zone, the β-columnar grain boundaries epitaxially grown from the interface are blurred and the adjacent grains are indistinguishable. The inside of the grains are rapidly dendritic dendrites with no α-phase precipitation. The zone is a bimodal structure formed by the transformation of equiaxed α and β. The primary acicular α-laths and secondary α-phase coarsening in the heat-affected zone. The results of microhardness test show that the microhardness of the deposition zone without α precipitation is the lowest, the highest in the substrate zone, and the microhardness of the heat affected zone is in the intermediate transitional distribution. Tensile results show that the strength of laser-repaired specimens is higher than that of forgings while the plasticity index is lower than the latter.