Study on hydrogen-induced delayed cracking of steering shaft

A 17-4PH steering shaft in the ship was brittle fractured during service, and its chemical composition, microstructure, fracture morphology of the material, and force simulations were analyzed. The results show that the failure mode of the shaft is hydrogen-induced delayed cracking, and the crack source is located on the outer surface of the contact position between the steering shaft and the end of the transfer shaft. Both the stress simulation analysis and the residual stress test prove that there is a greater stress concentration near the source region, which can easily lead to the migration and aggregation of hydrogen (H) during service, thus causing hydrogen-induced delayed cracking. The microstructure of a failure specimen with tempered and higher tensile strength will lead to higher sensitivity to hydrogen.