A knuckle joint of front suspension system in an all-terrain automobile failed within a few hundred miles of operation. Detailed failure analysis was carried out to determine if the failure of the knuckle joint was result of an accident or cause. Microstructural analyses revealed that the joint was manufactured by capacitor discharge welding of a zinc/phosphate plated shank to a case hardened ball. Possible hydrogen entrapment during zinc plating caused crack initiation at the heat affected zone (HAZ) because of higher hardness. Small cyclic loading re-initiated crack and it propagated through weld metal before final fracture occurred. In the internal hydrogen charged condition, presence of high mobile-dislocation density of weld metal (owing to faster solidification rate) acted as reversible traps of hydrogen. These mobile reversible sources of hydrogen helped reaching critical concentration at the potential flaw sites and crack propagation.