The deformation characteristics of alloy 800H and alloy 617

Abstract

The deformation behaviour of alloy 800H and alloy 617 was investigated in the temperature range 22–900°C. The true stress-true strain (σ-ϵ) plots show three stages of hardening: I, II and III. At 700–900°C, they show a steady state deformation stage which proceeds under constant values of stress, strain rate and temperature similar to steady state creep. When the steady state elongation was taken into consideration, the uniform elongation increased with increasing test temperature. The work hardening rate-stress (β-σ) plots at 22–900°C showed linear relationship between the work hardening rate θ and the flow stress σ in stage III hardening and could be described by Kock's equation based on Voce's. At 800–900°C the linear relationship between θ·σ and σ 2 observed in alloy 800H and alloy 617 is in agreement with the modified KM (Kocks-Mecking) model, in which the deformation behaviour is controlled by dislocation-particle interaction.