宽带激光熔覆工艺参数对熔覆层质量的影响

用金相检测法和能量平衡方程，推导并计算了激光熔覆过程中单位质量熔覆材料的比能Er和单位时间实际输入比能Eh，合理地解释了粉末有效利用系数、熔覆层稀释率随工艺参数变化的规律。结果表明，在激光参数不变的条件下，稀释率随扫描速度和送粉速率的增加而减小；粉末有效利用系数随扫描速度和送粉速率的增加而加大。熔覆材料损失机制主要是由于过热引起的烧损。

Effect of Processing Parameters for Broad Beam Laser on Quality of Cladded Coating

The concepts of the specific energy input E r and the specific heat energy E h were proposed. The equation expressing the relationship between the specific energy input and the specific heat energy was derived based on the energy equilibrium and metallographical measurement. The experimental method for determining E r and E h in laser coating processes by powder feeding method was designed. By varying the powder feeding rate and scanning speed under definited laser power and beam spot dimensions, the coating with different thickness was obtained. A reasonable explanation on the relationship between the effective utilization coefficient of powder, the dilution and the processing parameters was presented. The experimental results showed that the dilution becomes smaller and the effective utilization coefficient of powder becomes larger with the increase of the scanning speed and powder feeding rate. The main mechanism of powder losing is attributed to overheat.