扫描路径对薄壁件激光熔覆涂层形变的影响

Effect of scanning path on deformation of laser cladding coating on thin-walled part

为了改善收割机割刀等薄壁件在激光熔覆提升性能时容易产生形变的状况,采用Nd∶YAG激光加工系统在Hilbert分形式、轮廓偏置式和光栅式的3种不同的扫描路径下分别制备不同的铁基合金熔覆涂层,并取得了基材形变量和熔池深度等相关数据。结果表明,轮廓偏置式扫描路径在中心处的熔池深度最大,为0.75mm,且试样形变量达到了0.30mm;激光熔覆过程中熔池与其附近区域的温度梯度和基材形变量有着正相关的关系,熔池深度越大,温度越高,不同区域之间的温度梯度越大,产生的热应力越大,进而形变的倾向也会越大;光栅式扫描路径熔池深度随时间递增,温度梯度较小,故对基材的形变倾向较弱,且所制备的熔覆涂层质量较好,是适合于薄壁件激光熔覆的扫描路径。此研究对薄壁件激光熔覆具有指导意义。

In order to improve the current situation that thin-walled part such as harvester cutter are prone to deformation during laser cladding for their performance enhancement,three different Fe-based alloy cladding coatings were prepared by Nd∶YAG laser processing system under the scanning paths of Hilbert fractal,contour offset,and grating.The data of the deformation of the substrate and the bath depth were then obtained.The results show that the bath depth at the center of the contour offset scanning path is the largest,which is 0.75mm,and the deformation of the sample reaches 0.30mm;there is a positive correlation between the thermal gradient of the bath and its vicinity and the deformation of the substrate in the laser cladding process.The higher the temperature is,the faster the change is,the greater the thermal stress is,and the greater the tendency of deformation is.The bath depth in grating scanning path increases with time and the thermal gradient is small,so the deformation tendency of the substrate is weak,and the macroscopic feature is the best,which is suitable for the scanning path of laser cladding of thin-walled part.This study has guiding significance for laser cladding on thin-walled part.