Delayed ausforming in high-alloy ductile cast iron, part II: flow stress properties of cylindrical specimens

摘要

Cylinders of two, high-alloy ductile cast irons were austenitized at 927℃, quenched in salt at 375 ℃, and subjected to compression to a reduction in height of approximately 20% between heated platens at 375℃. Flow stress measurements were made over a range of times representing increasing amounts of ausferrite. It was observed that the yield stress increased linearly between a matrix of 100% austenite and a matrix of a fully transformed ausferrite. This resulted in increased energy requirements of deformation that more than doubled for a fully transformed ausferrite compared to specimens with 100% austenite matrices. The work hardening coefficient, n, decreased with increasing amounts of ausferrite. The yield stress measurements of the fully austempered specimens were consistent with tensile yield results at room temperature.