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Assessment of Data Transparency and Reproducibility

Kinetic model for bainite

This blog is about a paper by Huang, et al. (2026)

Huang H, Yang F, Chen P, Zhao H, Song D. Promoting Effect of Martensite on Bainite Transformation Kinetics: Unified Modeling Below and Above Martensite Start Temperature in 30Cr2Ni4MoV Steel. Journal of Materials Engineering and Performance. 2026 Feb 7:1-3.

While this publication about the kinetics of the bainite transformation is built on internal state variable theory and shear transformation, it basic foundations are entirely empirical. The model uses collaborative optimisation to align theoretical predictions with experimental dilatometry data. The application of the model is heavily dependent on collaborative optimisation with experimental dilatometry data. Since the equations on which it is based (e.g. equations 1-3) are empirical and contain numerous fitting parameters, the specific coefficients are tuned to the 30Cr2Ni4MoV steel grade.

The paper utilises numerous "material constants" and fitting parameters to calibrate the model. The authors do state the values for these parameters, or whether there is any ability to generalise to other steels without further fitting. The comments below are limited to a few of the parameters, there are more.

2. Generalisability of Empirical Parameters (C4–C8)

While the method is general, the specific numerical values of the material constants (C4, C5, C6, C7, C8) are strictly grade-specific.

Grade Sensitivity: These constants represent the "collaborative optimisation" of the model for 30Cr2Ni4MoV steel. Because they account for the specific chemical driving force (ΔGV) and interfacial energy (Sγb) of this particular alloy, they cannot be directly applied to other steels (e.g., high-carbon or silicon-rich steels) without recalibration.

Note that the driving force is empirically defined, and the interfacial energy function leads to a zero energy at the bainite-start temperature.

Need for Recalibration: To utilise this model for a different steel, a researcher would need to conduct similar thermal dilatometry experiments (such as those performed on the Gleeble 3500) to determine new values for these constants based on that steel's unique TTT and CCT characteristics.