Report on the stress corrosion cracking of prestressing steel tendons

This project, sponsored by the Australian engineering and building industries research association limited, describes an investigation and evaluation of the performance of prestressing wires used in prestressed concrete structures in terms of their susceptibility to stress corrosion cracking (scc) and/ or hydrogen embrittlement. An investigation was undertaken to determine the effect of steel condition, such as the microstructural characteristics and other metallurgical aspects on the susceptibility to scc by using c bend and uni axial specimens in various chemical environments. The environments were divided broadly into those containing sulphide and those not containing sulphide. It was found that the susceptibility of prestressing wires to scc is strongly dependent upon microstructure, surface defects and stress level. The presence of non metallic inclusions was also found to be an important factor in the initiation and propagation of cracks. The characteristics of the chemical environment such as the ph, the presence of sulphide ions and the application of polarisation were also found to be critical factors in determining the behaviour of materials. The metallography and fractography of scc of prestressing wires were established and provide guidance in the recognition of service failures (a).