Mechanical properties of Zr–2.5%Nb pressure tube material subjected to heat treatments in α + β phase field

Abstract

Heat treatment studies from α+β phase field were carried out on Zr–2.5wt%Nb alloy pressure tube (PT) material using quenching dilatometry. The effects of cooling rate and soaking temperature on the nature of β phase transformation and the morphological changes in the transformed products were studied using electron microscopy. The mechanical property variations in these heat-treated dilatometry specimens were studied using miniature specimen testing techniques such as Small Punch Test (SPT) and the Automated Ball Indentation (ABI) tests at room temperature. The effects of cooling rate and the soak temperature on the mechanical properties has been correlated with the microstructural features such as size and distribution of transformed products and their morphological characteristics. The present study has established that SPT and ABI techniques are sensitive to the microstructural changes resulting from different thermomechanical treatment and hence can be adopted to characterise the mechanical properties of pressure tube at various stages of manufacturing.