

Multiscale Crystal Plasticity Modeling of Microtwinning Induced Deformation in y-y¢ Nickel based Superalloys
Abstract
Nickel-based superalloys such as alloy 600 have been widely used in nuclear industry as steam generator tubes, through-wall nozzles and weld material due to their superior strength and corrosion resistance properties. Alloy 600 provides better resistance to stress corrosion cracking compared to SS304 grade of austenitic stainless steel. Alloy 182/82 have been used as welding electrode/ filler material and these are capable of depositing defect-free weldments in alloy 600. Recently, it was observed that alloy 600 is still subject to stress-induced reheat-cracking after long exposure to high purity reactor steam and primary water. As a result, a new nickel-based superalloy, i.e., alloy 690 along with alloy152/52 welding electrodes has been developed to replace alloy 600. Similarly, for intermediate heat exchangers of high temperature gas-cooled reactors, nickel-based superalloys are crucial due to their superior high-temperature strength and creep resistant properties.