Elevated temperature mechanical properties and corrosion characteristics evaluation of alloy Ht-9

This thesis presents the results of tensile testing, stress corrosion cracking (SCC) and localized corrosion studies of Alloy HT-9, which is currently being considered as a target structural material for transmutation applications. The results of tensile testing indicate that the yield strength and the ultimate tensile strength were gradually reduced with increasing temperature, but the ductility parameters were enhanced due to increased plastic deformation, irrespective of the tempering time. The results of SCC testing in the 90°C acidic solution, performed by the slow-strain-rate (SSR) technique, revealed higher failure stress (sigmaf) at longer tempering time. Localized corrosion studies conducted by polarization technique showed pitting and crevice corrosion in specimens exposed to both neutral and acidic environments. The fractographic evaluations of the primary fracture face of the broken tensile specimen by scanning electron microscopy revealed dimpled microstructure indicating ductile failure. Branched secondary cracks were observed along the gage length of the SCC test specimens, evaluated by optical microscopy