High-resolution topochemical analysis and thermochemical simulations of oxides and nitrides at grain boundaries and within the grains of a low alloy Mn-Cr hot-rolled steel sheet

The selective oxidation underneath the scale layer of an industrially hot rolled Fe-1.8Mn-0.8Cr steel at temperatures between 600 and 700 °C has been investigated. spatial distribution composition formed precipitates studied by high-resolution topochemical analysis via TEM-EELS NanoSIMS revealed heterogeneities in chemical composition, especially along grain boundaries. It could be shown that boundary oxides are predominantly composed aluminium, chromium or silicon oxides/nitrides, surrounded manganese-rich oxides. Experimental results phase stability have compared to numerical simulations, considering more than 40 potentially stable oxide-, nitride- carbide phases, differences critically discussed.