Study concerning quenching and partitioning as a path for optimizing retained austenite content in a potential TRIP steel

Abstract

Steels assisted by the TRIP effect have aroused the interest of several studies, particularly driven by the automotive sector and its needs. The multiphase microstructure of these steels, consisting of ferrite, martensite, bainite and retained austenite, is responsible for achieving excellent properties that allow the production of increasingly thinner sheets, reducing the weight of the parts without losing their original characteristics. The present study sought to produce a stable microstructure and quantify the volumetric fraction of austenite retained at the end of quenching and partitioning processing and identify the distinct structures present in the materials produced. The heat treatment cycles were determined to verify the routes with the highest percentage of retained austenite using the Koistinen Marburguer equation (1959). Microstructural characterization and mechanical behavior were conducted by optical microscopy (OM), X-ray diffraction (XRD) and hardness tests. It was found that higher quenching and partitioning temperatures produce a higher fraction of retained austenite. However, the carbon content of austenite is of fundamental importance in the microstructural stability of the steel produced.