Modelling the thermal creep behaviour of alloy D9 stainless steel clad tubes using Theta projection method

Uniaxial creep rupture properties of alloy D9 stainless steel clad tubes have been evaluated at 923 and 973 K over a wide range of stress levels. The creep strain-time data (creep curve) have been analysed following the 4 Theta and 6 Theta parametric approaches. The stress dependencies of the Theta parameters were established and used to predict the creep curves. By applying strain to fracture as the failure criterion, the rupture lives were predicted at various test conditions. The creep curves of alloy D9 stainless steel could be modelled reasonably well using the 6 Theta approach whereas modeling using 4 Theta parameters was not satisfactory. The predicted rupture lives showed good agreement with the experimental data.