为建立工艺参数与稀释率的关系,提出了送粉式激光熔覆过程中稀释率的概念,并推导出稀释率的表达式.利用金相法检测的熔覆层宏观参数、材料相关的物理参数和工艺参数对稀释率进行了计算,系统分析了影响因素.在激光功率和光斑尺寸保持恒定的条件下,稀释率随扫描速度的增加而减小,随送粉速率的增大而变小;对稀释率随扫描速度变化而出现最小值的现象给出了合理的解释.为进一步研究熔覆层组织凝固行为、工艺参数的优化奠定了理论基础.

In order to express the relationship between the dilution and the processing parameters, The concept of dilution is formulated. The equation expressing the relationship between the dilution and the parameters of the laser coated layer and the processing parameters was derived based on metallographical measurement. The experimental method for determining the dilution in laser coating process by powder feeding method was designed. By varying the powder feeding rate Vf and scanning speeding Vs under definite laser power P and beam spot dimensions, coatings with different thickness were obtained. The dilution was calculated with the help of metallographical measurement. The factors which affected the dilution were studied carefully. When the powder feeding rate and scanning speeding Vs increase, the dilution become smaller. A reasonable explanation on why a minimum value is observed in the relationship between the scanning speeding and the dilution is presented. In the meantime, it is the theoretical foundation for further investigation on the relationship between the microstructure,mechanism of solidification and the processing parameters.