Hot tensile properties and strain hardening behaviour of Super 304HCu stainless steel

Super 304HCu austenitic stainless steel containing 2.3-3 (wt.%) of Cu is mainly used in superheaters and reheaters tubing of ultra super critical boilers which operates over 600 °C of steam temperature. Tensile tests were carried out on Super 304HCu, using nominal strain rate of 1 × 10−3 s−1, at room temperature, 550 °C, 600 °C and 650 °C. The tensile strength and elongation were found to decrease with increase in test temperature. The stress strain curves were fitted using Hollomon equation to determine the strain hardening exponent value. Differential Crussard-Jaoul (C-J) analysis of the tensile curve is used to determine the variation in strain hardening exponent. Kocks-Mecking (K-M) type plots were used to determine the stages of strain hardening during tensile loading of the specimen. The strain hardening capacity of the Super 304HCu is found to decrease with increase in test temperature.