表面熔覆工艺的成形特征及粉末有效利用率研究

目的针对激光熔覆层的表面形貌难以达到加工工艺要求和粉末利用率较低的问题,对激光熔覆铁基合金粉末中的工艺参数与成形特征的关系以及粉末的有效利用率进行研究。方法设计了激光表面熔覆试验方案,分别采用不同的工艺参数在45号钢基板上进行铁基合金粉末单道激光熔覆试验。采用正交试验法对每道激光熔覆试验的工艺参数与成形特性之间的关系进行研究。结果随着激光功率的增加,熔宽、熔深、稀释率均呈上升趋势,浸润角和熔覆层的高宽比呈下降趋势,粉末的有效利用率由12.9%上升到42.6%;随着送粉速度的增加,熔高呈现上升趋势,熔深呈现下降趋势,粉末的有效利用率由27.9%下降到14.7%;随着激光扫描速度的增加,熔宽和熔高均呈下降趋势,粉末的有效利用率先增加后下降。结论送粉速度的增加造成粉末有效利用率的降低,增加了激光熔覆的作业成本。适当增加激光功率不仅可获得更加良好的激光熔覆层形貌,也使得粉末有效利用率增加。在激光功率为450 W,送粉速度为9.6 g/min和激光扫描速度为390 mm/min的条件下,不仅可以使粉末有效利用率处于较高的状态,也可以获得良好的熔覆层形貌。以上研究结果对激光熔覆的应用具有指导性作用。

Forming Characteristics and Powder Effective Utilization Research of Surface Cladding Process

The work aims to study the relationship between processing parameters and forming characteristics in laser cladding of Fe-based alloy powder and powder effective utilization rate for the problem that surface geometry of cladding layer is difficult to reach the processing requirements and the utilization rate of powder is lower. Test plan of laser surface cladding was designed and Fe-based alloy powder was used for single track laser cladding on the 45# steel substrate with different processing parameters. The relationship between processing parameters and forming characteristics of each laser cladding test was researched by orthogonal test. With the increase of laser power, clad width, melt pool depth and dilution rate increased, but infiltration angle and aspect ratio of cladding layer decreased. Meanwhile, powder effective utilization increased from 12.9% to 42.6%. With the increase of powder feed rate, clad height increased. However, melt pool depth decreased, and powder effective utilization decreased from 27.9% to 14.7%. With the increase of laser scanning velocity, clad width and clad height deceased, and powder effective utilization increased first and then decreased. Therefore, effective utilization of powder decreases as powder feed rate increases, which increases the cost of laser cladding. However, the proper increase of laser power can not only obtain good cladding layer geometry, but also increase effective utilization of powder. Under the condition of 450 W, 9.6 g/min and 390 mm/min, the powder effective utilization is high and good geometry of cladding layer is obtained. These experiment results provide some references for the application of laser cladding.