Effects of Al on Microstructure and High-Temperature Wear Properties of Austenitic Heat-Resistant Steel

Microstructure and high-temperature dry sliding wear at 600 °C in ambient air of austenitic heat-resistant steel ZG40Cr25Ni20 with different contents (mass percent) of Al (0 to 7. 10%) have been investigated. The results show that microstructures of 4. 68% and 7. 10% Al addition content consist of the matrix and reinforcement of inter-metallic compound γ' and carbide, while microstructures of ZG40Cr25Ni20 without Al and with Al of 1.68% are absent of γ'. Higher wear resistance than the original ZG40Cr25Ni20 alloy is achieved in alloys with higher content of Al under the same high-temperature wear test condition. The wear rates of Fe-25Cr-20Ni-7. 10Al and Fe-25Cr-20Ni-4. 68Al are only 20. 83% and 45. 83% of that of Fe-25Cr-20Ni, respectively. Heat-resistant steels with higher contents of Al (4. 72% and 7. 10%) have higher hardness than those with lower contents of Al (1. 68% and 0). Wear mechanisms of ZG40Cr25Ni20 are considered as severe plough plastic deformation and slight adhesive. However, wear mechanisms of Fe-25Cr-20Ni-4. 68Al are light micro-cutting and oxidation-wear, while that of Fe-25Cr-20Ni-7. 10Al are severe adhesive transfer and oxidation-wear.