The Quantitative Metallographical Characterisation of Hot Formed Duplex Steels

Abstract

Summary Image analysis investigations into the quantitative characterisation of hot formed duplex steel microstructures are presented. The shape parameters Feret diameter, Feret angle and roundness are used to describe the morphology of the microstructures. High temperature compression tests were carried out at 1 150 °C, 1 200 °C and 1 250 °C and the microstructures produced compared with that of the initial un-deformed material. The technical yield strength were also correlated with the temperatures and strain rate used. This revealed that the technical yield strength doubled by reducing the temperature of deformation from 1 250 °C to 1 150 °C and by increasing the strain rate by an order of magnitude. It is also shown that the pronounced preferential direction of the phases present in the initial un-deformed material is no longer quantitatively discernable above a temperature of deformation of 1 200 °C.