Material-specific phenomena and developing higher yield process parameters in laser powder bed fusion of 17-4 PH stainless steel

Although laser powder bed fusion has become attractive in industrial applications seeking a high geometrical complexity with short lead times and customization, some bottlenecks still exist for wider adoption. Build rate is one of them while the high number of process parameters and their interactions affecting the part performance is the second. The machine manufacturers supply parameter sets generally optimized for maximum density leading to good mechanical properties. However, other factors need to be considered in process development. This study aims at increasing the build rate for 17-4 PH stainless steel without any significant effect on the density, surface quality, material composition, mechanical properties and residual stresses. The results show an excessive ultimate tensile strength to yield strength ratio in comparison with reported literature which is attributed to the double yield phenomenon mainly attributed to the phases present in the microstructure as a result of powder chemical composition and processing gas. Thus, it is concluded for 17-4 PH stainless steel that the powder chemical composition and processing gas are much more effective on the investigated outputs while the process parameters that provide an increased build rate with almost full density do not significantly change.