Influence of titanium addition on the microstructure of the novel ferrous-based stainless steel

The microstructural characteristics of the Fe–9Al–30Mn–1C–5Ti (wt.%) alloy were determined by scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectrometry. The microstructure of the alloy was essentially a mixture of (γ + TiCx + (α + B2 + DO3)) phases during solution treatment between 950 °C and 1150 °C. The TiCx carbide had a face-center-cubic structure with a lattice parameter a of 0.432 nm. When the as-quenched alloy was subjected to aging treatment at temperatures of 450–850 °C, the following microstructural transformation occurred: (γ + TiCx + κ + (α + DO3)) → (γ + TiCx + κ + (α + B2 + DO3 + TiCx)) → (γ + TiCx + κ + κ′ + (α + B2 + DO3)) → (γ + TiCx + (α + B2 + DO3)). Addition of Ti promotes the formation of the α phase at high temperatures.

► The microstructure of the as-quenched alloy is a mixture of γ, (α + B2 + DO3), and TiCx phases.
► The TiCx carbide had a face-center-cubic structure with a lattice parameter a = 0.432 nm.
► Formation of the TiCx carbide causing a γ → (α + γ) transition in the matrix of the alloy.
► Addition of Ti promotes the formation of the α phase at high temperatures.