Study on the mechanism of heat and mass transfer behavior during multiple passes and multiple layers pulsed Laser cladding regarding the overlap ratio

Multiple passes and multiple layers overlap is a significant process to realize large area pulsed laser cladding forming. The complex heat and mass transfer behavior exists in this process, and the overlap rate is the key factor affecting the quality of the cladding forming. The different overlap rate can affect the solidification of the remelting zone, resulting in the change of the dilution rate on the cladding layer, and then change the concentration and distribution of elements. It is significant to reveal the mechanism of heat and mass transfer during multiple passes and multiple layers overlap forming for improving the cladding quality. In this paper, a heat-flow coupling model and a heat and mass transfer model were established in the overlap forming process of ASTM1045 disc laser pulse laser cladding Fe60 process. The influence law of different overlap rates on the instantaneous evolution of the temperature field, flow field and concentration field of cladding was analyzed. The mechanism of heat and mass transfer during cladding was clarified. The results show that the cladding temperature and flow velocity increase and the dilution rate decreases with the increase of overlap rate. The temperature, flow velocity and dilution rate of molten pool will increase with the increase of the number of cladding paths. With the increase of the number of cladding layers, the temperature and flow velocity of the molten pool will increase, but the dilution rate will decrease.