Effect of Annealing on the Microstructure and Mechanical Properties of a Low-Carbon Steel with Ultrafine Grains

The microstructures and properties of the ultrafine-grained low-carbon steel were investigated. Martensite microstructure was obtained by quenching a low-carbon steel, followed by 50% strain cold rolling and then annealing at 500–650 °C for 2 and 30 min, respectively. Microstructures were observed, and tensile properties were measured for the specimens treated with cold rolling and annealing. The effects of annealing parameters on the microstructure and mechanical properties were analyzed. It shows that the microstructure of specimen annealed at 550 °C for 30 min consists of ferrite grains with an average size of 330 nm. The ultrafine-grained low-carbon steel exhibits not only high tensile strength (867 MPa), but also good elongation (16.7%).