Investigation of temperature distribution and melt pool microstructure in laser fusion welding of Inconel 625 superalloy

Nickel-based super alloy laser welding is of particular importance because of its numerous usages in the energy and aerospace industries. Measuring the temperature field is the basic criteria for conducting a qualitative evaluation of the weld joint. In this research, laser welding was experimentally investigated and the temperature field was measured. Measuring the temperature around the molten pool by varying the laser parameters such as nozzle distance, welding speed, laser power, and beam offset indicated a different heat field, resulting in changes in the molten pool's width and depth. Because of the high temperature of melting and low thermal conductivity coefficient of the Inconel 625 alloy, the measured temperature was large. Compared with the other parameters, the effect of enhancing the laser power on temperature increase around the molten pool was significant. The findings showed that, by increasing the laser power from 300 to 400 W, the temperature increased from 320 to 340 °C. Also, by increasing the nozzle distance from the surface of the workpiece to 2 mm, the temperature decreased from 300 to 200 °C.