Study on Corrosion Resistance and Hardness of 17-4PH Steel for Aviation Fasteners after Different Heat Treatment

The effects of different heat treatment methods on the corrosion resistance, micromorphology and microVickers hardness of 17-4PH aviation fasteners were investigated. Firstly, the effects of different aging temperature on the corrosion resistance and hardness of the stainless steel were investigated under the premise of solid solution aging heat treatment. Secondly, the introduction of intermediate treatment between solid solution and aging treatment, and the effect of different intermediate treatment temperature on the corrosion resistance and hardness of 17-4PH stainless steel were investigated. The results show that, with the increase of aging temperature from 480 ℃ to 560 ℃, the corrosion resistance decreases and the Vickers hardness decreases, the number of precipitated phases increases and the size becomes larger. In addition, the corrosion resistance of 17-4PH stainless steel is greatly improved and the Vickers hardness is reduced by the introduction of intermediate treatment. With the increase of intermediate treatment temperature from 785 to 845 ℃, its corrosion resistance is further enhanced. The martensite shows the characteristics of fine and uniform. Moreover, the precipitation of NbC from austenite suppresses the appearance of chromium-poor zone.