Effect of cathodic charging on the mechanical properties of aluminum

Effects of Hydrogen Diffusion on the Mechanical Properties of Austenite 316L Steel at Ambient Temperature

“…Furthermore, the same trend was observed more apparently with Rockwell and Vickers hardness measurements. It is therefore believed that hydrogen softening could occur even with a small amount (several ppm levels) of internal hydrogen when it was evenly distributed, though there have been fewer reports on hydrogen softening 17,24,37) than hardening [38][39][40][41] in the literature. 42) In any event, it is difficult to understand their fundamental mechanisms and make direct comparison between them, because there has been a variety of sample geometries and testing conditions used in different studies.…”

Hydrogen effects on the interaction between dislocations

“…Studies of the eect of hydrogen on the macroscopic¯ow stress due to the presence of hydrogen in solid solution have yielded con¯icting results; a decrease in the¯ow stress has been reported in Fe [1±3], in Al [4] and in Ni [5], while an increase has been found by others in Ni [6], in Fe [7±9], in Al [10], in mild steel [7,8], and in stainless steels [11± 13]. Birnbaum [14,15] has suggested that this discrepancy may be attributed to the damage (generation of a surface phase or a high density of dislocations) that is produced by some of the methods used to introduce hydrogen.…”

The Effect of Cold Rolling on the Hydrogen Susceptibility of 5083 Aluminum Alloy

“…Microhardness tests on the cross section of charged aluminum specimens, with and without cold rolling, revealed a surface hardening due to hydrogen uptake with respect to the as-received material, Figure 3. The increase of the microhardness in the surface layers of the hydrogen charged alloys, can be either explained in terms of dislocation pinning mechanism [9,10] or based on the hydrogen enhanced localized plasticity (HELP) theory [12,13]. According to the first theory, hydrogen diffuses through easy paths, such as grain boundaries, into the surface layers of the alloy.…”

“…However, the mechanism of hydrogen incorporation into such aluminum alloys has not yet been unequivocally established [8]. Among the many proposed mechanisms [8], the most accepted are the traditional dislocation pinning theory first suggested by Troiano in 1960 [9] and followed by Watson et al in the 80 s [10], and the "hydrogen enhanced localized plasticity" (HELP) theory first proposed by Beachem in 1972 [11] and confirmed by the research group of Birnbaum et al [12,13].…”