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采用宏观和微观分析方法对3件失效的55CrSi钢弹簧的加工工艺和断口进行分析。结果表明3,件失效宏观断口均为脆性断裂,断裂源位于弹簧圈内侧,微观断口是沿晶脆性开裂且有许多内裂纹;失效弹簧均发生在热处理后的酸洗和镀锌处理工艺。失效的主要原因是,酸洗和电镀后氢渗入高强度弹簧钢基体,在弹簧圈内侧的拉应力作用下,经过一段时间后发生的氢致延迟脆断。同时提出了一些减少氢致延迟脆断的建议。
Using macroscopical and microscopic analysis methods, the machining process and fracture of three failed 55CrSi steel springs were analyzed. The results show that 3, the failure of the macroscopic fracture are brittle fracture, the fracture source is located inside the coil, the microscopic fracture along the crystal brittle cracking and there are many internal cracks; failure springs occurred in the heat treatment after pickling and galvanizing process. The main reason for the failure is that hydrogen pick-up and electroplating after penetration of hydrogen into the high-strength spring steel matrix, under the action of the tensile stress inside the coil, the hydrogen induced delay after a period of delay brittle fracture. At the same time, some suggestions to reduce the hydrogen induced delay and brittle fracture are put forward.