Plastic behaviour of SUS304 stainless steel tubes under intermittent uniaxial tensile loading

The plastic behaviour of SUS304 stainless steel tubes was investigated at room temperature via conventional single-round and intermittent uniaxial tensile testing (UTT), and the Hollomon model was adopted to describe the true stress-strain relationship under uniaxial tensile loading. The observed effects of the strain rate and unloading gap on tensile properties and the resulting stress-strain curves were interpreted in terms of microstructural transformation. The results indicate that the flow stress obtained by intermittent UTT was higher than that obtained by conventional single-round UTT, and the ultimate tensile strength (UTS) and tensile elongation decreased with an increase in the unloading gap. In addition, the yield strength increased with increasing strain rate, while the UTS and tensile elongation decreased. Further, both the strength coefficient and strain-hardening exponent used in the Hollomon model decreased with increasing unloading gap and strain rate.