激光快速成形过程的热行为及其影响

建立了激光快速成形(LRF)过程熔池的比色测温系统，分别采用实时跟踪和定点测量两种方式实现了熔池温度和熔池后沿冷却速率(温度梯度)的测量。结果表明，随着激光功率和送粉率的增大，熔池温度升高，熔池后沿冷却速率减小;随着激光扫描速度的增加，熔池温度下降，熔池后沿冷却速率增大。单道多层熔覆和多道搭接熔覆过程温度检测结果发现，随着沉积层数和沉积道数的增加，成形过程呈现热累积效应，即熔池温度逐渐升高，而熔池后沿的冷却速率则呈现完全相反的趋势。

Thermal Behavior and its Effect on the Process of Laser Rapid Forming

The temperature measurement system of melt pool produced in the process of laser rapid forming (LRF) is established by using a two-color infrared thermometer. The two methods named as real time tracking measurement and fixed point measurement are employed respectively to obtain the melt pool temperature and the cooling rate (temperature gradient) of the melt pool tail. The influences of LRF process parameters on the melt pool temperature are studied. The results show that with the increase of laser power and powder feeding rate the melt pool temperature rises. And the results just reverse as laser scanning speed increasing. With the number of deposition layer and deposition pass increasing, the LRF process presents characteristic of thermal accumulation effect, which means the melt pool temperature gradually elevates. Meanwhile the cooling rate (temperature gradient) of the melt pool tail takes on reverse trend.