Correction of flow stress and determination of constitutive constants for hot working of API X100 pipeline steel

Uniaxial compression tests of X100 pipeline steel were conducted to investigate its hot working behavior. Cylindrical specimens were compressed over a wide strain rate range of 0.001-50 s−1 and a temperature range of 850-1100 °C. Due to the heat generated from deformation and friction, the measured temperatures of compressed specimens at higher strain rates (≥1 s−1) deviated from the preset temperatures. Therefore, their measured stresses were corrected to obtain the true stresses at the pre-set temperatures before they were used for calculating constitutive equations. The Arrhenius-type constitutive equation was selected to describe the hot working behavior on the basis of corrected stresses. Strain-dependent constitutive constants were determined. The constitutive equation and corrected stress-strain data were both verified by using the results of additional tests at a strain rate of 20 s−1.