Hydrogen permeation in twinning-induced plasticity (TWIP) steel

Abstract

The hydrogen permeation behavior of twining-induced plasticity (TWIP) steel was studied using a Devanathan-Stachurski hydrogen permeation cell. The TWIP steel exhibited three orders of magnitude lower hydrogen permeation rate as compared to the mild steel at room temperature. The hydrogen permeation rate of the TWIP steel was 1.71 × 10−18 mol cm−1 s−1 at 25 °C, but it increased with the increase in the electrolyte temperature: 5.55 × 10−17 mol cm−1 s−1 at 30 °C, 6.56 × 10−17 mol cm−1 s−1 at 40 °C and 8.84 × 10−17 mol cm−1 s−1 at 50 °C. Interestingly, the effective hydrogen diffusivity of TWIP steel was significantly higher as compared to that of mild steel, at all the four test temperatures. Activation energy calculations suggest that the hydrogen permeation was primarily through the grain boundaries in TWIP steel, and therefore exhibited higher effective hydrogen diffusivity in comparison with mild steel.