Characteristic flow behaviour prediction and microstructure analysis of a commercial Si–Cr micro-alloyed spring steel under isothermal compression

This article explores the characteristic flow behaviour and microstructure analysis of Si–Cr spring steel under various compression conditions by a Gleeble 3500 facility. To better simulate the abrupt and complex compression during the hot forming process, three compression strain rates (0.01 s , 0.1 s , and 1 s ) and four compressive temperatures (850, 900, 950 and 1000 °C) were selected. The outcomes exhibit the intragranular dislocation cells and pile-up along the subgrains were formed during the dynamic recovery (DRV) progress. The dynamic recrystallisation (DRX) of the experimental steel arose with a higher value of the compression temperature. On this basis, a strain-compensated constitutive model considering the compression activation energy and a linear correlation between the Z parameter and DRX grain size are both established according to the strain-stress curves. The constitutive model is further verified by the multiple sets of hot deformation data and exhibits a good agreement between experimental and predicted points with an excellent correlation coefficient of 0.986 and a low relative error of 5.41%, indicating the reliability of the constitutive model throughout the entirety of the hot deformation process. −1 −1 −1