Competing Reactions in Quenching and Partitioning Steels: A Review of Models, Modifications, and Predictive Strategies

The quenching and partitioning (Q&P) process has emerged as a key heat treatment in developing the third generation of advanced high‐strength steels (AHSS 3rd Gen). The Q&P approach aims to generate microstructures with retained austenite, which can be stabilized by carbon enrichment during the partition step in order to achieve an optimal balance between strength and ductility. The carbon‐constrained equilibrium (CCE) model has been fundamental for establishing this heat treatment methodology. However, the original model does not account for competing reactions during partitioning, such as carbide precipitation, bainite formation, and carbon segregation in martensite, that can hinder austenite retention and compromise predictive accuracy. This review analyzes these competing reactions, focusing on how processing variables affect them. In addition, proposed strategies to mitigate or account for these reactions are explored, including alternative heat treatment methodologies, models that incorporate competing reactions, and modifications to the CCE model. Furthermore, the role of interface migration and the relevance of empirical equations in predictive models, as well as their impact on prediction accuracy, are also discussed.