| Tensile properties of quenched and tempered martensitic Alloy EP 823, a target structural material, have been evaluated at temperatures ranging from ambient to 600°C as a function of three different tempering times. The susceptibility to stress corrosion cracking and localized corrosion (pitting and crevice) behavior was determined by using slow-strain-rate (SSR) and cyclic potentiodynamic polarization (CPP) techniques, respectively. The results of tensile testing indicate that the yield strength and ultimate tensile strength were gradually reduced with increasing temperature. However, as expected, the ductility parameters were enhanced at elevated temperatures due to increased plasticity. The results of SSR testing, in the 90°C acidic solution, indicate that the failure stress was increased but the ductility was reduced to some extent at longer tempering times. The CPP results indicate that the critical potentials became more active (negative) at higher testing temperature. Evaluation of the primary fracture face by scanning electron microscopy revealed extensive cracks at ambient temperature but increased ductility at elevated temperatures showing larger plastic zone size. |
