Methodology for in-track grading in DED-LB by time-dependent powder feeder control

This study demonstrates continuous chemical grading of 316L and 17-4PH stainless steels within a single welding track in laser-based Directed Energy Deposition (DED-LB) by exploiting the transition between two powders. Transition- and response times of the powder flows were experimentally determined and incorporated into path planning to achieve grading within a single welding track. In-track gradients were confirmed by energy-dispersive spectroscopy (EDS) and hardness profiles. Relative densities above 99 % were achieved. The results demonstrate that in-track grading is reproducible without hardware modification and transition times scale proportionally with feeder rotation speed while response time remains nearly equal.