549 / 2019-01-16 18:45:29

Research on Microstructure Stability of Austenite Heat Resistant steels Tempaloy AA-1 and Tempaloy A-3 After Aging treatment

Tempaloy AA-1;Tempaloy A-3; aging; microstructure Stability; impact toughness

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The relationship between precipitation of M23C6 carbide and impact toughness of Tempaloy AA-1 and Tempaloy A-3 after long-term aging treatment at 650℃and 700℃ was investigated. The microstructure and impact fracture of Tempaloy AA-1 and Tempaloy A-3 steels after different of aging times were analyzed using scanning electron microscopy and transmission electron microscopy. The results show that M23C6 carbides at grain boundaries of Tempaloy AA-1 and Tempaloy A-3 are found as the aging time increases. When the aging treatment reached to 1000h, the impact absorbed energy begins to decrease. The impact absorbed energy of Tempaloy AA-1 is above 100 J after aging 8000h, whereas the impact absorbed energy of Tempaloy A-3 decreases to 20 J. There is no obvious reunion of M23C6 carbide after long time aging, so Tempaloy AA-1 steel still shows good microstructure stability. However, Tempaloy A-3 exhibits aging embrittlement due to aggregation and grown-up of M23C6 carbides at grain boundaries and brittle σ-phase precipitates inside grains after long time aging.