Thermomechanical properties of iron: viscoplasticity of ferrite and of austenite—ferrite mixtures

The available data on secondary creep in creep tests and on maximum stress in hot deformation tests obtained for δ and α ferrite have been reviewed and expressed in the form of the equation ϵ = K(σ/E)Pc sinh(Vσ/RT) exp(—Qc/RT) with pc = 2·5, V = 0·0013 m3 mol−1, and K = 2·6 × 1017 s−1, E and Qc being temperature dependent functions. The approximate range of validity is Z = ϵ exp (Qc/RT) ≈ 101—1011 s−1. Together with the corresponding equation for austenite the data can be used to predict the viscoplastic behaviour of austenite—ferrite mixtures.MST/1538