In the automotive industry many high strength steel fasteners are zinc electroplated. The plating process is thought to be a principal cause of hydrogen embrittlement: fasteners can fail unpredictably at applied stress levels well below the fracture stress. To avoid this a hydrogen relief heat treatment after electroplating is commonly applied. In this study the effect of plating and post-plating treatments on the slaw strain rate tensile fracture behaviour of two commercial steels has been investigated. Testing was conducted on fatigue pre-cracked cylindrical specimens in air. Results describing the effect of alloy selection, metallurgical processing conditions and heat treatment on the susceptibility to hydrogen embrittlement are presented. The principal conclusion drawn from this study is that post-plating hydrogen relief annealing, as specified by international standards, is not always of benefit.
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