Optimization and Characterization of a Quenching and Partitioning Heat Treatment on a Low-Carbon Steel

摘要

Increased requirements for low fuel consumption and improved safety in the automotive industry have stimulated the development of new generations of high strength steels. A promising way of achieving a favourable compromise between strength and ductility is by a so called Quenching and Partitioning (Q&P) heat treatment by which a martensitic microstructure with a considerable amount of fine-dispersed retained austenite can be produced. A low carbon steel composition was designed based on thermodynamic calculations whereby 3 wt% Mn is added to suppress bainite formation and 1.5 wt% Si to avoid cementite precipitation. Quenching and partitioning cycles were designed in order to obtain the maximum retained austenite fraction and performed in the thermo- mechanical simulator Gleeble™. The microstructures and mechanical properties were characterized by scanning electron microscopy, X-ray diffraction, electron backscatter diffraction (EBSD) and tensile tests respectively. The results of tensile tests were finally correlated with the Q&P parameters and microstructures.