Failure analysis on fracture of stainless steel tie rod

The stainless-steel tie rod of a trial-produced vehicle model fractured after being left stationary for 24 hours after assembly. The fracture occurred at the welded joint of the stainless-steel tie rod. The failure causes of the stainless-steel tie rod were analyzed through methods such as macroscopic observation, scanning electron microscopy analysis, chemical composition analysis, metallographic and hardness testing. The results show that the failure mode of the stainless-steel tie rod is hydrogen-induced cracking. The excessively high carbon content in the tie rod material and the appearance of martensite structure in the weld and heat-affected zone during the welding process are the root causes of the hydrogen-induced cracking.