Hot deformation behaviour and constitutive modelling of P92 heat resistant steel

摘要

Hot compression tests are conducted in the present paper to investigate hot deformation behaviour of the newly developed heat resistant steel P92, which is used to fabricate main steam pipes for ultra supercritical power plants. Stress-strain curves at elevated temperatures and different strain rates are obtained. It is found that dynamic recrystallisation happens only when the temperature is above 1100°C and strain rate is below 0.1 s~(-1). Otherwise, dynamic recovery is the main softening mechanism. Constitutive modelling with the hyperbolic sine, including an Arrhenius term, is used to predict peak and saturated stresses. Material constants for this model are determined. Results show that the model can be used to predict peak and saturated stresses. However, the model would fail in predicting flow stress with respect to strain; thus, a model containing nine independent parameters and the complete form of Spittel equation are utilised to predict flow stress curves softened by dynamic recrystallisation and dynamic recovery respectively since there are no unified equations. The predicted stress-strain curves are in good agreement with experimental results, which confirmed that the models developed in the present paper are effective and accurate for P92 steel.