Quantum mechanics

Phase (matter)

Engineering

CALPHAD

Metallurgy

Materials science

Metastability

Stability (learning theory)

Ductility (Earth science)

Computer science

Chemical engineering

Creep

Quenching (fluorescence)

Thermodynamics

Physics

Organic chemistry

Thermal

Microstructure

Fluorescence

Austenite

Phase diagram

Isothermal process

Diffusionless transformation

Bainite

Chemistry

Martensite

Thermal stability

Machine learning

Toughness

Journal of Material Science and Technology

Metastable austenite plays a critical role in achieving improved combinations of high strength and high ductility/toughness in the design of advanced high-strength steels (AHSS). The thermal stability of metastable austenite determines the transformation characteristics of AHSS and thus primarily determines the microstructure evolution during complex processes, e.g., the quenching and partitioning process, to achieve the desirable microstructure. This study provides a review of the thermal stability of austenite and its influence on martensitic transformation from both experimental and theoretical modeling perspectives. From the experimental perspective, factors affecting the thermal stability are analyzed, the relative sensitivities are compared, and their corresponding mechanisms are discussed. From the theoretical modeling perspective, the most representative kinetic models that describe athermal and isothermal martensitic transformation are reviewed. The advantages, shortcomings, and applicability of each model are discussed. The systematic review of both experimental and theoretical aspects reveals critical factors in tailoring the stability of metastable austenite and, therefore, provides guidance for the design of advanced steels.

A review of the thermal stability of metastable austenite in steels: Martensite formation