A New Kinetic Mode During the Austenite-to-Ferrite Transformation in Fe-Mn and Fe-Mn-Mo Alloys

doi:10.1007/s40195-020-01026-y

Abstract

Abstract:

The kinetics of isothermal austenite (γ)-to-ferrite (α) transformation at various temperatures in Fe-2Mn and Fe-2Mn-0.5Mo (wt%) alloys is investigated via dilatometry experiments and phase-field modeling. It was interestingly found that Mo addition has a marginal effect on the transformation kinetics. Besides the well-known partitioning and partitionless transformation modes, a new kinetic mode, in which interface migration is controlled by interfacial diffusion, was identified. The phase-field model with considering interfacial segregation could well predict the transformation kinetics and the kinetic mode transition.

Key words: Steel, Austenite, Ferrite, Diffusion, Solute drag

Cong-Yu Zhang, Hao Chen, Jia-Ning Zhu, Chi Zhang, Zhi-Gang Yang. A New Kinetic Mode During the Austenite-to-Ferrite Transformation in Fe-Mn and Fe-Mn-Mo Alloys[J]. Acta Metallurgica Sinica (English Letters), 2020, 33(7): 975-980.

Figures/Tables 5

Table 1 Chemical compositions and T0 for the two alloys

Alloy	Composition (wt%)			T₀ (°C)
Alloy	Mn	Mo	Fe	T₀ (°C)
Fe-2Mn	2.08	-	Bal.	802
Fe-2Mn-0.5Mo	2.11	0.49	Bal.	809

Fig. 1 Ferrite (α) fraction as a function of time during isothermal holding at various temperatures in a Fe-2Mn, b Fe-2Mn-0.5Mo alloys

Fig. 2 Austenite (γ)-to-ferrite (α) transformation in an Fe-2Mn alloy, a the experimental α/γ interface velocity compared with PFM predictions at different temperatures, and the predicted Mn profiles at b 780 °C, c 740 °C, d 700 °C

Fig. 3 Austenite (γ)-to-ferrite (α) transformation in an Fe-2Mn-0.5Mo alloy, a the experimental α/γ interface velocity compared with PFM predictions at different temperatures, and the predicted solute profiles at different time at b 780 °C, c 740 °C, d 700 °C (the arrows on the axis indicate the positions of interface)

Fig. 4 Experimental α/γ interface velocity during γ → α transformation in an Fe-2Mn alloy and an Fe-2Mn-0.5Mo alloy

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