Hydrogen-induced cracking and service safety evaluation for precipitation strengthened austenitic stainless steel as hydrogen storage tank

• Hydrogen-induced failure always occurs at the weld not at the base material.
• The normalized threshold stress decreased with the increase of tc.
• The diffusion coefficient of hydrogen in the weld is about 1.13 × 10−11 cm2/s.

The safety of precipitation strengthened austenitic stainless steels used for hydrogen storage tanks is of great interest. However, their application may face hydrogen damage resulting in hydrogen-induced delayed failure. Results show that over-loading and hydrogen-induced failure always occur at the weld part of the alloy. Hydrogen damage such as microcracks could be observed on the surface of the matrix and the weld during charging even without any applied stress. Hydrogen-induced failure occurred during charging under constant load and the normalized threshold stress decreased exponentially with increasing defined time tc. It is shown that the threshold stress with no hydrogen-induced failure occurring for expected service life, i.e. forty years, was 713 MPa. Therefore under the service stress, which is less than the threshold stress, 713 MPa, the safety factor of the hydrogen storage tank for hydrogen-induced fracture is great enough to indicate the tank to last for the entire designed service time.