Influence of the workpiece accumulated heat on the bead forming and microstructural material properties in LMD-wire cladding process

Laser cladding is a technology for depositing protective layers on components operating in extreme environments. The protective layer is made of a more durable material that extends the life of the part. Identifying the optimal process parameters to make the layer is usually challenging and typically requires expert knowledge and empirical tuning. One of the reasons that make it difficult to find the optimum parameters is the heat accumulation in the part during long duration cladding, which changes the resulting quality of the layer with constant parameters.This study investigates the effect of heat accumulation on cladding bead geometry, dilution and material microstructure. At the same time, the cladding process was monitored by two temperature sensors. A pyrometer was used to measure the melt pool temperature, and a thermal camera was used to monitor the temperature change of the whole part. Two strategies differing in laser power settings were compared. In one strategy the power was constant and in the other strategy the power was reduced over time.From the data analysis was found, that heat accumulation has the greatest effect on material dilution and on the symmetry of the cladding bead geometry. Both parameters were improved by reducing the laser power even though the heat accumulated in the part still increased its temperature.These findings show that heat accumulation influences the quality of the welded layer, but by using sensors it is possible to monitor the accumulation and react by reducing the power. This research demonstrates the effectiveness of real-time thermal monitoring and adaptive power control to help achieve robust feedback control of laser cladding technology.