Residual Stress as a non-destructive indicator of hydrogen uptake in titanium

Hydrogen uptake in structural metals can lead to hydrogen embrittlement (HE), degrading mechanical performance in energy and infrastructure systems. However, common quantification techniques, such as thermal desorption spectroscopy (TDS) and inert gas fusion (IGF), are destructive and unsuitable for in-service monitoring.

This work establishes perceived residual stress, measured by X-ray diffraction using the cos-α method, as a quantitative, non-destructive indicator of hydrogen uptake in commercially pure titanium (cp-Ti). Samples were electrochemically charged to achieve hydrogen concentrations of ~50–250 ppm, as measured by IGF. A strong linear correlation (R² ≈ 0.995) was observed between hydrogen content and residual stress, with increasing hydrogen producing more compressive stresses.

Complementary sin²ψ analysis confirmed lattice strain evolution with hydrogen uptake, while TDS measurements of low-energy trapped hydrogen showed consistent increases with charging time.

Vickers microhardness mapping revealed localized changes, with hardness increasing from ~145 HV (uncharged) to ~180–195 HV after 18–24 h, and up to ~230 HV at longer charging times.

These results highlight X-ray diffraction as a sensitive, non-destructive method for monitoring hydrogen uptake and enabling early detection of hydrogen-related degradation in titanium systems.