Temperature and time effects of post-weld heat treatments on tensile properties and microstructure of Zircaloy-4

Abstract

Opportunities exist to expand the application of Zircaloy-4 (Zry-4) into lower-temperature (800°C or >18hours) cases, but the effect of temperature was stronger. The second order cumulative annealing parameter shows a trend with tensile properties. Average grain sizes in the fusion zone and heat affected zone did not change under any of the PWHTs until the development of an undesirable blocky-alpha phase, which was only observed to form in the heat affected zones for hold times greater than 18hr at 800°C.