Wednesday  |  Phipps  |  02:50 PM–03:10 PM

#13585, Fatigue Testing of Additively Manufactured 17-4PH Stainless Steel Samples with a Stress Concentration

In this paper, the tensile response due to quasi-static and fatigue loading of Additively Manufactured (AM) 17-4 Precipitation Hardened (PH) Stainless Steel (SS) was assessed. Samples in this study were produced using a Markforged MetalX printer which utilizes the Atomic Diffusion Additive Manufacturing (ADAM) process. Samples were washed and sintered according to the Markforged specifications which are noted to be typical of 17-4 PH SS. Quasi-static and load controlled fatigue tests were conducted on a sub-sized dogbone geometry per ASTM E8 where samples had a circular stress concentration in the form of a hole at the center of the sample width. The hole created a stress concentration factor of approximately 2.37 on average with the precise dimensions left in an as printed state. Digital Image Correlation (DIC) was used to analyze the strain fields which will be reported in this document at the top, side, and far away from the hole. For quasi-static results the stress is reported as the force divided by the whole sample cross-sectional area with the strain determined by the DIC analysis. The axial failure strain at the edge of the hole was approximately 5 % while the average elastic modulus away from the stress concentration was on average 170 GPa. Fatigue testing was conducted at a rate of 5 Hz and an R ratio of 0.1 for a fatigue cycling in the range of 1 to 3e5 cycles collecting time, displacement, load, and strain data. Typical signal response per cycle showed increasing displacement/strain over time until ultimate failure.

Michael Coatney   United States Army Research Laboratory
Bradley Lawrence   United States Army Research Laboratory
Todd Henry   United States Army Research Laboratory
Latha Nataraj   United States Army Research Laboratory
Clifford Hubbard   United States Army Research Laboratory