Laser direct metal deposition of variable width thin-walled structures in Inconel 718 alloy by coaxial powder feeding

Abstract

For the laser direct metal deposition (LDMD) based on coaxial powder feeding, the width of the clad track is difficult to change in real time, so it is difficult to realize the manufacture of the variable width thin-walled (VWTW) structures. In the present study, a variable width method with multi-track deposition was proposed to solve the problem of variable width forming of the coaxial powder feeding system. The variable width and the same height are achieved by changing the overlapping rate and the scanning speed. The mathematical model of the shape-forming process of variable width thin-walled parts among geometric dimensions of thin wall, overlapping rate, scanning speed, and Z axis increment is carried out. Single-layer and multi-layer variable width structures were deposited to validate the proposed mathematical model. The microstructure and properties of the formed part varied with the width of a thin wall. Different variable width thin-walled parts and a blade-type part were fabricated to verify the feasibility of the forming method and the accuracy of the mathematical model in real life. The width and height of the manufactured parts fulfill the design requirements.