Fatigue Properties of Reinforcing Steel Produced by TEMPCORE Process

TEMPCORE is a patented mill process that produces high-strength reinforcing steel bars via in-line quenching and self-tempering. This paper reports on the fatigue performance of 400 MPa-grade reinforcing steel produced by TEMPCORE process, called TEMPCORE steel in this paper. Seven bar diameters were axially fatigue-tested in air, and the results in terms of S-N curves and failure features are presented, and compared with test data for other types of reinforcing steels from the literature. Comparisons indicate that this type of reinforcing steel has higher fatigue resistance. Although the general geometrical features are similar to those of other types of reinforcing steels, existing models fail to predict its fatigue properties. It is suggested that the metallurgical microstructure and residual stresses developed during the TEMPCORE process contribute to the superior fatigue properties and must therefore be considered in the models.