Investigating microstructural properties of ferrite/bainite dual-phase steel through simple process control

The ferrite/bainite dual-phase microstructure is obtained through controlling two-phase region temperature in the designed medium carbon steel. The influence of the two-phase region temperature on microstructure morphologies and volume fraction, as well as mechanical properties, is thoroughly studied. The microstructure at 795°C heat treatment process exhibits excellent strength and elongation. This is attributed to the increased proportion of large-angle misorientation, the better deformability between ferrite and bainite, and the TRIP effect of retained austenite. The strain hardening exponent curve of the sample subjected to the 795°C heat treatment process does not intersect with the straight-line n = e until the strain reaches the value of 0.1, which results in high tensile strength and high uniform elongation.