Effect of Aluminum Content on Microstructure and Impact-Abrasion Resistance of ZGMn18Cr2 Lightweight High-Manganese Steel

: Test steels containing different aluminum mass fractions （0.29%, 3.93%, 6.98% and 10.97%） were prepared by adjusting the aluminum content of ZGMn18Cr2 lightweight high manganese steel. The influence of aluminum content on the microstructure, mechanical properties and impact-abrasion behavior was investigated. The results show that when the aluminum content was in the range of 0.29 %‒6.98 %, the microstructure of the test steels consisted of austenite and dot-like κ-carbides. As the aluminum content increased to 10.97 %, a dual-phase microstructure of austenite and ferrite with crystallographic twins was formed in the test steel. With increasing aluminum content, the impact absorbed energy of test steels first increased and then decreased, reaching its maximum at the aluminum mass fraction of 3.93 %; the hardness continuously increased, the yield and tensile strengths initially decreased and then increased; the elongation after fracture first increased and then decreased, reaching its maximum （about 48.5 %） at the aluminum mass fraction of 6.98 %. After wear for 1 h under impact energies of 0.5 J and 3.5 J, the test steel with aluminum mass fraction of 3.93 % exhibited the lowest mass loss, indicating the best impact-abrasion resistance; its work hardening rates were also the highest, reaching 151% and 169%, respectively. At the low impact energy of 0.5 J, the dominant wear mechanisms were micro-cutting and plastic deformation. Under high impact energy （3.5 J）, the wear mechanism shifted from fatigue spalling to brittle interfacial decohesion along phase boundaries with the increase of aluminum content.