Effect of Inter-Critical Annealing Temperature on the Sliding Tribological Properties of Hot-Rolled Al-Contained Medium Manganese Steel

Typical wear-resistant high manganese steel in the low stress friction conditions of the lack of work hardening ability, the corresponding working conditions of wear resistance is not ideal. Medium manganese steels have great potential in the field of wear-resistant steels due to their simple forming process and low cost. To Investigate the tribological performance advantages of medium manganese steel under sliding conditions and optimizing the composition of C, Mn, and Al elements, we developed a wear-resistant hot-rolled medium manganese steel with the nominal composition of Fe-5Mn-3.2Al-0.35C (mass fraction/%), referred to as 5MnAl. This study placed particular emphasis on the influence of annealing temperatures on the microstructure and wear resistance of new-type medium manganese steel. After hot rolling and quenching, 5MnAl exhibited a full martensitic structure. Annealing at 650 ℃ results in a mixed structure of ferrite and carbide, while inter-critical annealing at temperatures ≥700 ℃ led to a reverse transformation into an austenite and ferrite structure. As the annealing temperature rose, the retained austenite content initially increased and then experiences a slight decrease. Under sliding friction conditions, 5MnAl demonstrated superior performance compared to BTW wear-resistant medium manganese steel. At each annealing temperature, it exhibited a lower friction coefficient and wear rate. Notably, 5MnAl annealed at 650 ℃ exhibited the lowest wear rate under a 10 N load. Moreover, after annealing at 700 ℃ and testing at a 20 N load, its wear resistance was approximately 3.5 times that of BTW steel. At higher loads, 5MnAl annealed at 800 ℃ demonstrated the lowest wear rate, owing to its significantly high strain hardening. The primary wear mechanisms observed in medium manganese steel were abrasive wear、adhesive wear and fatigue wear. A deeper understanding of the strain hardening mechanism in medium manganese steel promised to advance its wide-ranging applications in the field of tribology.