Experimental study on the distortion of TI-6AL-4V substrate during laser deposition

Laser deposition shaping is widely used to strengthen and repair the Ti-6Al-4V thin-walled parts. However, significant distortion was inevitable for these parts during laser deposition process because of high temperature gradient and rapid thermal cycles produced by the laser heat source. Firstly, to investigate the distortion characteristics, laser deposition experiments were performed on Ti-6Al-4V substrate by various processing parameters, such as laser power, scanning speed, etc. The effects of various processing parameters on macro-size of Ti-6Al-4V single bead depositing layer were researched. At the same time, the microstructure of the titanium alloy deposit was observed by scanning electron microscope (SEM), and the micro-hardness of the deposited layer was tested. The influence of different laser deposition parameters on the microstructure and micro-hardness of the deposited layer was obtained. The results provide guidance for optimizing process parameters to improve the laser deposition quality. Secondly, the effects of laser deposition on the distortion of Ti-6Al-4V plates with different thickness was investigated using the optimized process parameters. The distribution of residual stress was measured. It is shown that the plates of different thickness have different sensitivity to the laser deposition. The research could give practical insight into repairing thin-wall Ti-6Al-4V parts.