Prediction of Ar₃ during Very Slow Cooling in Low Alloy Steels

抄録

Considering the partition behavior of substitutional alloying elements, a computing method is developed to predict the starting temperature of proeutectoid ferrite transformation (Ar₃) in low alloy steels during cooling. The paraequilibrium γ/(α+γ) phase boundary temperature (denoted Para Ae₃) and local equilibrium partition to no-partition transition temperature are calculated using Thermo-Calc software in Fe-C-M₁, Fe-C-M₁-M₂ and Fe-C-M₁-M₂-M₃ (M₁, M₂ and M₃ denote substitutional alloying elements) low alloy steels. Compared with Ar₃ taken from published CCT diagrams, it is found that the transition temperature from partitioned to no-partitioned growth agrees relatively well with Ar₃ when the cooling rate is less than 1°C/min.