Detection and analysis of melting behavior of powder coaxially fed laser

During coaxial powder laser coating, the interaction between powder and laser directly affects the forming accuracy and quality of cladding. It is impossible to directly obtain the melting behavior of powder in laser and analyze the heat absorption of powder by infrared camera. Therefore, by analyzing the absorption of heat by powder, the dynamic behavior of powder melting was collected by high-speed camera system and the dynamic analytical model of powder melting process was established. The influence of laser power on different melting stages and the temperature characteristics of powder entering molten pool were simulated and analyzed. The results show that the dynamic melting behavior of the powder in the laser of the high-speed camera acquisition system has three typical melting characteristic stages of 'solid → solid-liquid two-phase → liquid'. The dynamic behavior of powder melting can be analyzed by mathematical analytical model, and the thermal physical behavior of different stages has a dynamic analytical model of the interaction between powder and laser heat. The effects of laser power, off-focus value and the flow rate of the gas carrying the powder on the melting behavior of powder were analyzed. At the same time, the effects of different laser power on the duration of each characteristic stage were simulated and analyzed, and the temperature distribution of powder particles reaching the substrate was predicted. It was found that when the laser power increased from 100 W to 1500 W, the temperature of the powder entering the molten pool changed nonlinearly, and the temperature increased from 750 ℃ to 3 250 ℃.