Failure analysis of cold drawn prestressing steel wires subjected to stress corrosion cracking

This paper analyzes the stress corrosion performance of cold drawn prestressing steels with different degrees of cold drawing, in the two cases of pure stress corrosion cracking and fracture by hydrogen embrittlement. Results show a progressively anisotropic stress corrosion behaviour with cold drawing, and this anisotropy could be induced by the microstructural orientation. Consequences for engineering design are derived on the basis of the calculation of the transition stress intensity factor (from the stress corrosion subcritical crack growth to the critical cleavage propagation). While in situations of pure stress corrosion cracking such a value is even higher than the fracture toughness of the material in air (due to crack tip blunting), in the case of hydrogen embrittlement there is a marked reduction of stress intensity factor value, which indicates that these steels are highly susceptible to this phenomenon.