Comparative tensile flow and work hardening behaviour of thin section and forged thick section 9Cr-1Mo ferritic steel in the framework of Voce equation and Kocks-Mecking approach

摘要

Detailed analysis indicated that true stress (σ)-true plastic strain and work hardening behaviour of 9Cr-1Mo steel in two different forms, i.e. 20 mm plate and thick section tubeplate forging can be adequately described by Voce equation and Kocks-Mecking approach in the temperature range 300-873 K. The steel exhibited two-stage work hardening in the variations of instantaneous work hardening rate (θ = dσ/d) and θσ with stress. The variations in σ-, work hardening parameters, θ-σ and θσ-σ with temperature exhibited three distinct temperature regimes. Good correlations between the predicted tensile properties using Voce equation and the respective experimental values along with analogy between Voce equation and Kocks-Mecking approach have been demonstrated for the steel. The differences in σ-, work hardening parameters, θ-σ and θσ-σ observed between plate and tubeplate forging have been ascribed to the effects associated with initial microstructures for the two product forms of the steel.