Comparison of Two Methods of Cold Work to Increase Strength of Hot Rolled Reinforcing Bar—A Further Study

Abstract

Strengthening of reinforcing bar is compared after two methods of cold working, i.e. tensile and torsional prestraining. When achieving any fixed value of yield strength (YS) both tensile and torsional prestraining give approximately the same value of ductility, determined by a uniaxial tensile test. The experimental tensile yield strength following tensile prestrain is higher than the experimental tensile yield strength following torsional prestrain with reference to the effective prestrain. This difference has been partitioned by the predicted tensile YS following torsional prestrain. One part, i.e. between YS following tensile prestrain and predicted YS following torsional prestrain, is accounted for by the method of determination of effective prestrain. The other part, i.e. between predicted and experimental YS following torsional prestrain, is accounted for by the Bauschinger effect, residual stress effects and difference in hardening law when torsional strain is compared with tensile strain.