1前言 航空部某所生产的伺服阀,在装配过程中,拧紧固定螺栓时发生断裂。受该所委托,我们对该件进行了分析。 该壳体的材料是9Cr18,生产工艺流程为:初加工→调质→精加工→热处理→探伤……,热处理工艺为:光亮淬火(1020～1040℃保温30～40min)油冷,冰冷处理(-50～-80℃2h),回火(150～170℃,保温2—4h)。为判断断裂的性质,初步找出断裂的原因,对断口及金相组织进行了分析。 1 Foreword A servo valve produced by the Ministry of Aeronautics breaks down during the assembly process when tightening the fixing bolts. By the commission, we analyzed the piece. The shell material is 9Cr18, the production process is: initial processing → quenching and tempering → finishing → heat treatment → testing ... ..., heat treatment process: bright quenching (1020 ~ 1040 ℃ insulation 30 ~ 40min) oil cooling, -50 ~ -80 ℃ 2h), tempering (150 ~ 170 ℃, heat 2-4h). In order to judge the nature of fracture, the reason of fracture was initially found out, and the fracture and microstructure were analyzed.