Hydrogen Embrittlement in Al-added Twinning-induced Plasticity Steels Evaluated by Tensile Tests during Hydrogen Charging

Abstract

Hydrogen embrittlement of a Fe-18Mn-0.6C-1.5Al steel was observed in tensile deformation during cathodic hydrogen charging. The fracture mode was quasi-cleavage fracture. The relationship between diffusible hydrogen content and fracture stress was arranged by the power law like that for ferritic and Al-free TWIP steels. The Al addition did not affect the magnitude of the degradation of hydrogen embrittlement property at the same current density in TWIP steels. However, the Al-added steel showed a suppression of hydrogen entry and a larger total elongation in comparison to those of the Al-free TWIP steel in the same environment, although the Al addition decreased fracture stress. The larger elongation is one of the reasons for why the Al addition improves the hydrogen embrittlement property of cup specimens.KEY WORDS: high Mn austenitic steel; twinning-induced plasticity steel; hydrogen embrittlement; tensile testing under hydrogen charging.

The effect of Ti precipitates on hydrogen embrittlement of Fe–18Mn–0.6C–2Al–xTi twinning-induced plasticity steel

“…Fortunately, the addition of Al greatly improved the resistance to HE of Fe-high Mn-C TWIP steels [13,16,[19][20][21][22][23]. Chin et al [16] reported that the HE did not occur in Fe-18Mn-0.6C-1.2Al TWIP steel due to the homogeneous distribution of residual stress by the uniform formation of mechanical twins during the cup forming test.…”

“…Chun et al [20] reported that the resistance to HE of Al-bearing TWIP steels was improved due to a low level of residual stress. Koyama et al [22] observed that both the hydrogen concentration and elongation loss were decreased in Al-bearing TWIP steels. Park et al [13] reported that an oxide layer of a-Al 2 O 3 formed on the surface of the Al-bearing TWIP steel during electrochemical hydrogen charging and the oxide layer prevented hydrogen permeation into the specimen.…”

Factors Affecting Static Strain Aging under Stress at Room Temperature in a Fe–Mn–C Twinning-induced Plasticity Steel

“…3) Static strain aging is important since it causes hydrogen embrittlement and is also a strengthening method. Fe-Mn-C TWIP steels were recently reported to show hydrogen embrittlement [4][5][6][7][8][9][10] which causes a serious problem, since they are expected to be used for automobile parts with significant residual stress. 4) In our previous studies, the hydrogen embrittlement susceptibility of TWIP steels was found to decline when the static strain aging was suppressed.…”

Critical Assessment 2: Hydrogen induced fracture in austenitic, high-manganese TWIP steel

“…There is some controversy on the amount of hydrogen absorbed during cathodic charging when the TWIP steel contains aluminium. Early studies claimed that aluminium reduces the absorption of hydrogen, 21,34 but it has recently been reported that aluminium increases the hydrogen uptake. 15,20,35 The discrepancy is unexplained, but the mechanism for reduced hydrogen absorption is proposed to be associated with the presence of an oxidation layer on the steel surface during cathodic charging, a layer that hinders the ingress of hydrogen.…”