Effects of different annealing temperatures on microstructure, mechanical properties, and magnetic properties of cold-rolled 20Mn23AlV non-magnetic structural steel

The variations in the mechanical and magnetic properties of cold-rolled 20Mn23AlV non-magnetic structural steel after annealing at different temperatures were investigated. The microstructure and precipitation changes during annealing were studied by optical microscopy, scanning electron microscopy, and transmission electron microscopy. The results show that recrystallization completed after annealing at 620 °C, resulting in grain sizes of approximately 800 nm and the best combination of strength and plasticity. The yield-to-tensile ratio of the non-magnetic structural steel after cold rolling continuously decreases from low to high temperatures after annealing, with the highest value being 0.89 and the lowest value being 0.43, indicating a wide range of yield-to-tensile ratio adjustment. The introduction of numerous dislocations during cold rolling provided favorable nucleation sites for precipitation, leading to abundant precipitation of the fine second-phase V(C, N). The phase composition of the samples remained unchanged as single-phase austenite after annealing, and the relative permeability values were calculated to be less than 1.002, meeting the requirements for non-magnetic steel in terms of magnetic properties.