Abstract
Hydrogen embrittlement often acts as a governing mechanism for stress corrosion cracking, so the study of hydrogen behavior in additively manufactured (AM) stainless steels is critical in the evaluation of corrosion performance. This work aims to characterize hydrogen-assisted stress corrosion cracking in selectively laser melted (SLM) 316L and 17-4 PH stainless steels through the study of hydrogen diffusion and trapping behavior via the determination of total, trapped, and diffusible hydrogen content. A Barnacle Electrode experimental setup was used to measure diffusible hydrogen concentration at various cathodic charging potentials for each SLM build direction of the various conditions, allowing for the comparison of hydrogen uptake between wrought and AM steels as well as between the anisotropic directions of each individual condition. The hydrogen trap states and their corresponding binding energies were identified for each bulk condition using thermal desorption spectroscopy (TDS) with temperature programmed desorption (TPD) and compared to microstructural characteristics. Devanathan-Stachurski permeation was also used to quantify the effective hydrogen diffusion coefficient of the different build directions in comparison to wrought 316L and 17-4 PH. LECO Hydrogen testing was employed to measure total hydrogen uptake by means of vacuum hot extraction. Results indicate differences in hydrogen uptake behavior between wrought and AM 316L and 17-4 PH, respectively.