A viscoelastic-viscoplastic constitutive model for high-temperature response of an advanced steel verified by biaxial measurement experiments

This paper presents a viscoelastic-viscoplastic constitutive model for representing different aspects of the high-temperature deformation response of advanced martensitic steel. The model decomposes the strain into three components of elastic, viscoelastic, and viscoplastic. The elastic behaviour is represented by Hooke's law; 2 K-Voigt models in series are used for the viscoelastic response, and a variant of the two back-stress terms Chaboche model is employed for the viscoplastic part. The effectiveness of the proposed model has been examined for representing the deformation behaviour of a 10%Cr martensitic steel at 600 °C. It has been shown that the developed model provides a sufficiently accurate description of i) constant-load creep after various prior loadings, ii) constant-strain stress-relaxation, iii) anelastic recovery, and iv) negative creep behaviour of the 10%Cr steel. The model results are compared with those from a three back-stress terms Chaboche viscoplastic model to indicate the importance of considering the viscoelastic component. Furthermore, observations from biaxial measurements of axial and radial deformation for a uniaxially loaded testpiece were used to demonstrate the necessity of considering the viscoelastic contribution for accurately representing the high-temperature deformation response of steels. [Display omitted] •Developing a constitutive viscoelastic-viscoplastic model for high-temperature response of an advanced martensitic steel.•Employing Kelvin-Voigt and Chaboche based models for viscoelastic and viscoplastic responses with back-stress and drag-stress.•The model can represent cyclic/constant-load creep, constant-strain stress relaxation, anelastic recovery and negative creep.•Comparing results with previous models in literature to indicate the importance of considering the viscoelastic component.•Biaxial measurements of axial and radial deformation for a uniaxial test showed the necessity of viscoelastic contribution.