DYNAMIC IMPACT RESPONSE OF NANOSIZED PRECIPITATES BEARING WASPALOY

الملخص

Dynamic response of nanosized precipitates bearing (NPB) Waspaloy, a class of superalloy, is crucial to design structural components for critical rotating applications and other severe dynamic impact predisposed applications. The focus of this study is, therefore, to investigate the compressive dynamic behaviour of NPB Waspaloy at a high strain rate under various deformation conditions. The technique of modified split Hopkinson pressure (MSHP) bar was implemented through impact deformation of Waspaloy under wide-ranging deformation temperatures (-180 - 750 oC) and strain rates of (4*103 - 7.5*103 s-1). The outcomes of the experiments divulge how to flow stress relates directly to strain rate and is inversely proportional to deformation temperatures. Work hardening rate affects NPB Waspaloy maximally at the iciest deformation temperature (-180 oC) and the highest strain rate (7.5*103 s-1) considered. Under high straining and high rate of straining deformation conditions, the rate with which work-hardening occurs is destabilized due to the thermal softening effect during deformation. It is established that when strain is constant, the flow stress dependency on the rate of straining depicts linear relation. The thermal softening effect on NPB Waspaloy is concerted at around extreme strain rate (7.5*103 s-1) and iciest deformation temperatures within -180 ~ 25 oC. Mapping of strain, strain rate and deformation temperatures representing input parameters with the resultant flow stress provide an unambiguous analytical view of the effects of dynamic impact deformation. Flow stresses at elevated temperatures are correlated directly with grain growth, mainly influenced by adopted deformation temperatures.

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