Effect of Microstructure on Hydrogen Permeation in EA4T and 30CrNiMoV12 Railway Axle Steels

Abstract

A comparative study was conducted to reveal the effect of microstructure on hydrogen permeation in the EA4T and 30CrNiMoV12 railway axle steels. Unlike the EA4T with its sorbite structure, 30CrNiMoV12 steel shows a typical tempered martensitic structure, in which a large number of fine, short, rod-like, and spherical carbides are uniformly dispersed at boundaries and inside laths. More importantly, this structure possesses plentifully strong hydrogen traps, such as nanosized Cr7C3, Mo2C, VC, and V4C3, thus resulting in a high density of trapping sites (N = 1.17 × 1022 cm−3). The hydrogen permeation experiments further demonstrated that, compared to EA4T, the 30CrNiMoV12 steel not only delivered minimally effective hydrogen diffusivity but also had a high hydrogen concentration. The activation energy for hydrogen diffusion of the 30CrNiMoV12 steel was greatly increased from 23.27 ± 1.94 of EA4T to 47.82 ± 2.14 kJ mol−1.

A comparative study of microstructure and hydrogen embrittlement of selective laser melted and wrought 17–4 PH stainless steel

“…This might be correlated to the higher grain boundary density in the martensitic microstructure, as it is known that grain boundaries can be trapping sites for hydrogen [53]. However, it should be noted that the diffusion coefficient found for the ferritic SLM-ed steel is approximately two to three orders of magnitude lower than that of a typical ferritic microstructure [54][55][56]. This could be due to additional trapping sites, possibly correlated to the formation of Cu-rich precipitates during ageing (4 hours at 580°C).…”

Preferential Locations of Hydrogen Accumulation and Damage in 1.2 GPa and 1.8 GPa Grade Hot-Stamped Steels: A Comparative Study

“…studies have indicated that carbides, such as nano-sized NbC, VC, and TiC, are often identified as "good irreversible straps" with high hydrogen binding energy (Eb > 60 kJ mol −1 H), decrease hydrogen diffusivity and increase critical hydrogen concentration in steel, leading to enhanced resistance to HE [26]. Therefore, reduced hydrogen damage is expected for A-1800 steel.…”

“…The formation of carbides is directly associated with the increased carbon and the introduced micro-alloying elements (see Table 1), which also strongly improved the strength of steel to 1.8 GPa. Previous studies have indicated that carbides, such as nano-sized NbC, VC, and TiC, are often identified as "good irreversible straps" with high hydrogen binding energy (E b > 60 kJ mol −1 H), decrease hydrogen diffusivity and increase critical hydrogen concentration in steel, leading to enhanced resistance to HE [26]. Therefore, reduced hydrogen damage is expected for A-1800 steel.…”

Study on the corrosion fatigue properties of ultrasonic surface strengthened axle steel

“…Its fatigue destruction is often accompanied by corrosion. Although the fatigue, corrosion, and hydrogen embrittlement of axle steel have been studied extensively, the interaction of these factors is rarely studied [2][3][4]. As known, corrosion fatigue starts from the active points of the material surface.…”