Effect of hot rolling reduction and annealing treatment on grain boundary character distribution in austenitic low-density Fe-Mn-Al-C-Cr steel

Grain boundary engineering in the austenitic low-density Fe-Mn-Al-C-Cr steel was implemented by simple annealing treatment at 1100 °C for 30 min after hot rolling with 66% and 80% reduction. The fractions of low-Σ coincidence site lattice (CSL) boundaries have exceeded 60% after hot rolling, and reached 77% after annealing treatment. Whether after hot rolling or annealing, the fractions of Σ9 and Σ27 in samples with 80% reduction were obviously higher than those with 66% reduction. It indicated that hot rolling reduction was the key to realize grain boundary character distribution optimization. The results showed that the connectivity of random high angle grain boundaries was broken through the formation of large grain clusters only occurred in the sample with 80% reduction, which inhibited the grain growth during annealing. It provided a convenient method to carry out grain boundary engineering.