EFFECT OF STRAIN-AGING ON THE STRENGTH COEFFICIENT AND STRAIN-HARDENING EXPONENT OF CONSTRUCTION-GRADE STEELS

Two construction-grade steels-G40.21 350 WT and G40.21 350 AT-were ten sile tested under a range of temperature and strain-rate conditions. R esults showed that both the strain-hardening exponent and strength coe fficient at first decrease with increasing temperature, then increase with increasing temperature and reach a maximum at a temperature betwe en 523 and 573 K before decreasing. With increasing temperature, the s train-rate dependence of the strain-hardening exponent and the strengt h coefficient changes from positive to negative. This behavior reflect s the effects of strain aging on the strain-hardening exponent and the strength coefficient.