Influence of carbon concentration and magnetic transition on the austenite lattice parameter of 30Mn-C steel

Abstract In this study, the effects of carbon concentration and magnetic transition on the austenite lattice parameter of Fe-30Mn-xC alloys were assessed. A linear relationship was obtained between the carbon content and the lattice parameter determined by neutron diffraction and neutron Bragg-edge transmission imaging for austenitic steels bearing 0.007–1.20 mass% C. The results obtained through both methods showed good agreement. In addition, carbon partitioning was evaluated in artificially piled-up discs with different carbon contents in order to develop a new technique for advanced multi-phase steels. The analysis of asymmetry and broadening of the diffraction line profile revealed that the carbon partitioning could be determined. In addition, the Neel temperature was determined by in situ neutron diffraction upon heating and cooling with magnetic diffraction peaks and the change in the lattice parameter with temperature being monitored. The temperature dependence of the austenite lattice parameter was found to become smaller below the Neel temperature. In conclusion, the results presented herein expand the current knowledge on the properties of high Mn austenite.