A method for controlling ultra-precision deformation of thin-walled double-shell titanium alloy bushing during high temperature nitriding

Abstract

The invention belongs to the technical field of metal heat treatment, and relates to a high-temperature nitriding ultra-precision deformation control method of a thin-walled double-shell titanium alloy bushing. The invention uses a titanium alloy ion nitriding furnace with an auxiliary heat source, constructs an equipotential local negative glow area space with the help of an auxiliary cathode cylindrical tooling, and adopts mechanical shielding to prevent the hollow cathode effect between the shells of the double shells. , the tooling and the effective working area in the ion nitriding furnace overlap the geometric centers. During the ion nitriding, the temperature is raised in steps of 300-450°C, 500-650°C, heat preservation and cooling, and the heat preservation time is 2-4 hours. The cooling rate is controlled at 0.5-4°C / min, high-temperature annealing at 850-950°C before nitriding, the glow heating system is started when the temperature is raised to 300-400°C, and nitriding is carried out at 750-880°C for 6-20 hours. Through the comprehensive application of the above means, the present invention realizes the ultra-precise control of the high-temperature ion nitriding deformation of the thin-walled double-shell complex structure titanium alloy bushing parts, and the deformation amount does not exceed 0.020mm.

Description

technical field [0001] The invention belongs to the technical field of metal heat treatment, and relates to a high-temperature nitriding ultra-precision deformation control method of a thin-walled double-shell titanium alloy bushing. Background technique [0002] Due to the strong chemical affinity between titanium and oxygen and nitrogen, high-temperature ion nitriding can only be used for titanium alloy nitriding. The in-situ binding with the matrix titanium atoms improves the nitriding rate. The thermal conductivity of titanium alloy is low. During the heating process, the internal and external temperature rise of the part is inconsistent, which leads to serious deformation when it is nitrided at a high temperature above 750 ° C, especially the double-shell titanium alloy bushing with thin effective wall thickness and extremely complex structure. , after the ion nitriding is completed, the ellipse deformation needs to be controlled within 0.020mm. According to relevant l...

AI Technical Summary

Problems solved by technology

The thermal conductivity of titanium alloy is low. During the heating process, the internal and external temperature rise of the part is inconsistent, which leads to serious deformation when it is nitrided at a high temperature above 750 ° C, especially the double-shell titanium alloy bushing with thin effective wall thickness and extremely complex structure. , after the ion nitriding is completed, the ellipse deformation needs to be controlled within 0.020mm. According to relevant literature and data retrieval, the current existing technology cannot meet this technical requirement.

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