Hydrogen Embrittlement of Metals

Abstract

Hydrogen interacts with many metals to reduce their ductility (2) and frequently their strength also. It enters metals in the atomic form, diffusing very rapidly even at normal temperatures. During melting and fabrication, as well as during use, there are various ways in which metals come in contact with hydrogen and absorb it. The absorbed hydrogen may react irreversibly with oxides or carbides in some metals to produce a permanently degraded structure. It may also recombine at internal surfaces of defects of various types to form gaseous molecular hydrogen under pressures sufficiently high to form metal blisters when the recombination occurs near the outer surface. In other metals, brittle hydrides that lower the mechanical properties of the metal are formed. Another type of embrittlement is reversible, depending on the presence of hydrogen in the metal lattice during deformation for its occurrence. Under some conditions the failure may be delayed for long periods. A number of different mechanisms have been postulated to explain reversible embrittlement. According to some theories hydrogen interferes with the processes of plastic deformation in metals, while according to others it enhances the tendency for cracking.

Reduction of Copper Oxide Films by an Atmospheric-Pressure Inductively Coupled Plasma Microjet

“…The pore formation was due to the entrapment of H 2 molecules at the grain boundary [12,13]. Internal Cu 2 O layer was partially reduced after the plasma treatment at 15 W with the treatment time less than 30 s.…”

“…This phenomenon is known as hydrogen embrittlement and could be explained by the hydrogen segregation to grain boundaries. The solubility of H atoms in Cu increases with temperature [13]. The surface temperature of the sample was elevated with the plasma process time.…”

“…When the plasma treatment was finished, the substrate temperature was decreased rapidly, lowering the solubility of H atoms. H atoms were then precipitated at the grain boundary of reduced Cu to initiate bubbles containing H 2 gas [12,13].…”

Influence of dissolved hydrogen on the fatigue crack growth behaviour of AISI 4140 steel

“…Hydrogen enters the metal surface, in a variety of ways as explained above, lodges itself as an interstitial solute only in the atomic form [33][34]. This reduces the load bearing capacity of the material.…”

Segregation at the surfaces of CuxPd1−x alloys in the presence of adsorbed S

“…[22][23][24][25] In practice, pure Pd membranes suffer from structural instability in the presence of H 2 . [26,27] Furthermore, exposure of a Pd membrane to H 2 S, a common impurity in coal-derived gas streams, degrades membrane performance by poisoning the surface for H 2 dissociation and inhibiting H-atom diffusion through the bulk. [19][20][21]28] To address these challenges, Pd has been alloyed with a variety of minor components, including Cu, Ag and Au.…”