Hydrogen embrittlement failure of hot dip galvanised high tensile wires

A case of failure of high carbon eutectoid steel wires is investigated. Dur ing the production stage, i.e. cold drawing and subsequent coiling/strandin g operations, the wires of similar to 4.0 mm diameter failed by central spl itting along longitudinal planes. Microscopic examination, fractography and mechanical tests along with acoustic emission monitoring were carried out on the wire samples. The experimental results confirm that the failure is r elated to hydrogen embrittlement which has been characterised by fractograp hy, strain rate sensitivity and susceptibility to delayed fracture as indic ated by acoustic activity. It has been argued that the ahead of pre-existin g cracks, can explain the failures observed in the present case. It appears that improper pickling and subsequent baking processes, during the final s tages of drawing operations, are responsible for the hydrogen related failu res.