A comparison of the microstructure and creep behavior of cold rolled HAYNES 230 alloy™ and HAYNES 282 alloy™

HAYNES 282 and HAYNES 230 nickel-based superalloys were subjected to cold rolling deformation and heat treatments in order to investigate processing-microstructure-property relationships to understand the effects of thermomechanical processing on their microstructure and tensile-creep behavior. The sheet materials underwent four cycles of 20% reduction in thickness followed by a solution treatment. The resultant microstructures were characterized using electron backscattered diffraction and electron microscopy, and the high-temperature (973-1088 K (700-815 °C)) creep and fatigue behavior was evaluated and compared to the commercially available sheet alloys. The thermomechanical processing treatments did not significantly affect the grain boundary character distribution and almost half of all the boundaries in the microstructures were twin boundaries. The creep resistance was shown to degrade with the additional thermomechanical treatments, which resulted in finer equiaxed grain sizes. The HAYNES 282 alloy was shown to be significantly more creep resistant than the HAYNES 230 alloy. The fatigue behavior indicated that creep ratcheting occurred more prominently in the HAYNES 230 alloy than in the HAYNES 282 alloy and this was explained to be a result of the superior creep resistance exhibited by the HAYNES 282 alloy. Overall, this study suggests that additional energy-intensive processing treatments, beyond those involved in the commercially available sheet products, may not be beneficial for additional creep resistance.