Investigating Additively Manufactured 17-4 PH for Structural Applications

This study takes a benchmarking approach to the processing of 17-4 PH using selective laser melting by having two facilities that use their own best practices to process materials. Hot isostatic pressing (HIP) is used by both facilities as part of the thermomechanical processing following printing to explore whether it can improve the consistency of mechanical properties. Results revealed that HIP reduced average porosity of 17-4 parts and that the yield strength of parts following solutionization and aging met wrought material property targets. Strain to failure of one of the facilities parts was less than 5% compared to greater than 9% for the other facility. Inspection of failure surfaces revealed this discrepancy was caused by pores (2-4% area fraction) on the failure surfaces of the low ductility parts. These results are viewed with respect to the intended application of this material as a structural element for wind tunnel testing.