The deformation induced ferrite structure of Q235 steel was got with heating at 950 °C for 5 min

1°C/s cooling to 855 ℃ for 30 s and reduced 80% at strain rate 15 s

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then quenching by Gleeble 1500 thermal simulation machine

and the pro-eutectoid ferrite structure of the steel was got by heating at 950 °C for 5 min

furnace cooling. Test results showed that the grain size of deformation induced ferrite was ≤5um average HV value 229. 55

tensile strength 809 MPa

while the grain size of pro-eutectoid ferrite was 10 - 20 μm grain un-uniform

average HV value 210. 28

tensile strength 736 MPa. The mechanism of thermodynamics and kinetics of the deformation induced ferrite and pro-eutectoid ferrite are analyzed in this paper.