Influence of annealing process on microstructure and mechanical properties of C-Mn dual phase steel

The paper deals with the influence of annealing parameters on the evolution of microstructure and mechanical properties of a dual phase steel. Simulation of annealing regimes by thermo-mechanical simulator Gleeble was conducted. The dual phase steel was annealed in laboratory conditions in accordance with three specified annealing cycles: into intercritical region (780 degrees C, into austenite region (920 degrees C) and into austenite region (920 degrees C) by subsequently cooling into intercritical region (780 degrees C) with the hold at the temperature of 495 degrees C. Dwell time at 495 degrees C simulates submerging of steel sheet into zinc bath. The obtained microstructure consists of three phases: ferritic matrix, martensite, and martensite/bainite grains. To identify the microstructure, transmission electron microscopy (TEM) and nanoindentation experiments were performed.