Manyalibo Matthews’ Post

In previous publications by the LLNL team, tailoring laser energy input spatially and temporally has been shown to control microstructure and residual stress in laser powder bed fusion (L-PBF) additive manufactured parts. In this latest work, led by Kaila Bertsch and first-authored by Connor Rietema, the use of large area surface annealing with a secondary diode laser is investigated as a method to control the microstructure of Ti6Al4V during L-PBF. To determine the effect of layer annealing on the microstructural development through the height of AM Ti6Al4V components, all cylinders were built with the same initial parameters but different in-situ diode annealing schedules. Temperature gradients that developed in the parts during annealing were determined by measuring the surface temperature with an infrared camera and the base plate temperature with a thermocouple, then applying a simple, conduction-only thermal simulation to model the temperature throughout the height of the build. With this framework, the microstructural evolution could then be tied to the temperature history. This information is critical to developing annealing strategies that localize heat treatments for complete 3D spatial control of the microstructure. The work was co-authored by John Roehling and William L. Smith. https://lnkd.in/d8e9h8wk