In laser and electron beam direct metal additive manufacturing, characteristics of the melt pool and the resulting final parts are a product of a variety of process parameters. Laser or electron beam spot size is an important geometric input parameter that can affect the size and shape of a melt pool, and has a direct influence on the formation of lack-of-fusion and keyholing porosity. In this work, models are developed to gain a better understanding of the effects of spot size across different alloys and processes. Models are validated through experiments that also span multiple processes and alloys. Results for melt pool dimensions as a function of spot size are presented. Methods to expand the usable processing space are demonstrated in the ProX 200 laser powder bed fusion process. It is demonstrated that in-depth knowledge of process parameters can reduce the occurrence of porosity and flaws throughout processing space and allow for the increased use of non-standard parameter sets.
- Expand the range of process variables they can use on their laser powder bed machines by altering beam spot size.
- Avoid keyholing-induced flaws entirely.
- Substantially increase fatigue lives.