发动机用Ti600钛合金激光送丝熔覆参数优化及性能表征

为了改善发动机用Ti600钛合金表面性能,采用激光送丝熔覆工艺对其表面进行加强,并通过实验测试方法对熔覆工艺参数进行了优化。经过综合考虑确定参数范围:200 W激光功率、1.4 mm/s扫描速率、5 mm/s送丝速度。组织性能得到:最优参数下熔覆层在底层熔覆组织中形成了胞状外形的晶粒,中间由许多细长柱状晶组成,上部存在许多细小的等轴晶。热影响区形成了片状结构的马氏体组织,有许多残留的奥氏体结构。硬度测试得到:熔覆层的硬度最大,其次为热影响区,硬度最低的是基体区域,硬度变化范围介于720~910 HV之间。随着温度上升,热影响区硬度也表现为正比提高的现象,激光送丝熔覆能够对晶体缺陷起到一定的修复效果。

Characterization of Ti600 Ti-Alloy Surfaces Modified by Laser-Cladding of SKD11 Wire

Ti600 Ti-alloy,an advanced aerospace engine material,was surface-modified by laser cladding of SKD11 wire.The influence of the wire feed-rate,laser power and scanning speed on the microstructures and surface hardness was investigated with scanning electron microscopy and energy dispersive spectroscopy.The results show that the optimized laser cladding conditions included:a laser-power of 200 W,a scanning rate of 1.4 mm/s and a wire feed-rate of 5 mm/s.The equiaxial grains,columnar grains and cellular grains occupied,respectively,the top,middle and bottom of the clad-layer; laminar martensite and some austenite dentrites coexisted in the heat-affected zone(HAZ).The hardness,varying in 720~910 HV range,followed a descending order:clad layer>HAZ-layer>Ti600 Ti-alloy,possibly because of formation of Cr-carbide and V-carbide.We suggest that laser cladding of SKD11 wire be feasible for repairing of macroscopic damages on surfaces of Ti600 Ti-alloy.