Effect of Hydrogen on the Structure and Mechanical Properties of 316L Steel and Inconel 718 Alloy Processed by Selective Laser Melting

Abstract

The interaction of hydrogen with specimens of 316L steel and Inconel 718 alloy processed by selective laser melting (SLM) was studied. The effect of hydrogen on the mechanical properties of SLM materials, hydrogen permeability, and microstructure was investigated; besides, these values were compared with the properties of conventionally produced materials. It was shown that SLM can be successfully used to produce parts for operation in hydrogen environments at high pressure at room temperature.

Influence of dislocation cells in the hydrogen diffusivity, trapping and embrittlement of wrought and additively manufactured Inconel 718

“…The diffusivity calculated from ITDS results shows a good agreement with literature values of wrought Inconel 718 for different metallurgical conditions [45,71], as shown in Fig. 6 and Table 3.…”

“…Furthermore, there is a need for (1) a hydrogen trapping assessment in fully saturated samples to gain insight into the nature of the preferential trapping sites that in uence crack initiation and propagation; and (2) a hydrogen diffusivity and uptake assessment for samples with the same thickness as for tensile tests, which will enable correlating HE susceptibility indexes to hydrogen content. Recently Maksimkin et al [45] provided a hydrogen diffusivity value in annealed samples based on gas permeation studies. However, such studies are time-consuming and challenging to perform.…”

Effects of Wall Thickness Variation on Hydrogen Embrittlement Susceptibility of Additively Manufactured 316L Stainless Steel with Lattice Auxetic Structures

“…There are two competing factors which affect the HE susceptibility of AM316L SS: the surface roughness and the hydrogen trapping sites [ 19 , 20 , 21 , 22 , 23 , 45 ]. Hydrogen atoms effectively diffuse into the rough surface as the surface flaws and other imperfections, such as pores, serve as entrances for the H atoms, as reported in the literature [ 24 , 44 , 45 , 52 ].…”

“…Various studies have been conducted on the HE susceptibility of 3D-printed 316L-SS [ 19 , 20 , 21 , 22 , 23 , 24 ]. These studies have found that volumetric defects, sub-grains in the cellular structure, and the melt pool boundaries present in selective laser melted (SLMed) 316L-SS act as potential trapping sites for H atoms.…”

“…Moreover, the stain fields around the edge dislocations work as reversible H-trapping sites (with activation energy less than 60 kJ/mol), which promotes the HE susceptibility [ 21 , 25 ]. Nevertheless, the HE resistance of 316L-SS produced by the LPBF technique is better than its counterparts produced by conventional methods due to the enhanced strength originating from the existing sub-grains in the cellular structures as well as the austenite being more stable in the LPBF specimens [ 21 , 22 ]. The latter property minimizes the strain-induced transformation of austenite into martensite in the LPBF structures compared with the conventional 316L-SS [ 15 , 21 , 26 ], since H reduces the stacking fault energy of the austenitic steels [ 27 , 28 ].…”