Dynamic Recrystallization Behavior of High Deformability Pipeline Steels

The dynamic recrystallization behavior of high deformability pipeline steel was studied by a Gleeble-3800 thermal simulator under different compression deformation conditions, and the austenite morphology was observed by optical microscopy and scanning electron microscopy. The true stress-true strain data were analysed by linear regression method to obtain thermal deformation equation of the tested steel. The results show that partial dynamic recrystallization temperature zone was 920-1 020 ℃ when =1 s-1 and ε=0.30. The strain for partial dynamic recrystallization was 0.20-0.40 at 980 ℃ and 1 s-1, and the strain had little effects on austenite recrystallization grain size. The dynamic recrystallization completed mainly when ε=0.4, and when 0.40＜ε＜0.60 many times dynamic recrystallization took place, and recrystallization grain size decreased with the increase of strain. The hot deformation activation energy of the tested steel was 360.365 kJ·mol-1 and the stress index was 4.326 3 at 950~1 100 ℃.