Intergranular to transgranular transition in the stress corrosion cracking of Zircaloy-4

Stress corrosion cracking susceptibility of Zircaloy-4 wires was previously studied in 1 M NaCl, 1 M KBr and 1 M KI aqueous solutions and in iodine alcoholic solutions. In all cases, intergranular attack preceded transgranular propagation. It is generally accepted that the intergranular-transgranular transition occurs when a critical value of the stress intensity factor is reached. In the present paper it was confirmed that the transition from intergranular corrosion to transgranular propagation in Zircaloy-4 wires occurs when a critical value of the stress intensity factor is reached. This critical stress intensity factor in wire samples is independent of the solution tested and close to 11 MPa m^−1/2. This value is in good agreement with those reported in the literature measured by different techniques and with different specimen geometries.