Nanocrystalline Advanced High Strength Steel Produced by Cold Rolling and Annealing

An advanced high strength steel of composition Fe-0.11C-2.46Si-11.5Mn-0.38Al-0.029N (wt pct) was produced with a yield strength of 790 MPa, an ultimate tensile strength of 1300 MPa, and a total elongation of 28 pct. Conventional processing of hot-band steel by cold rolling and annealing at 873 K (600 degrees C) was used to produce a nanocrystalline structure with an average grain diameter 112 +/- 25 nm (68 pct confidence level). Electron backscatter diffraction (EBSD) and X-ray diffraction (XRD) were utilized to characterize the nanocrystalline steel, which consisted of gamma-austenite, epsilon-martensite, and alpha-ferrite. (C) The Minerals, Metals & Materials Society and ASM International 2016