A kind of ti-containing carburized steel for thin-walled inner gear, its manufacturing method and method for forming thin-walled inner gear

Abstract

The invention discloses a Ti-containing carburized steel for thin-walled internal gears, a manufacturing method thereof and a forming method for thin-walled internal gears. The chemical composition of the Ti-containing carburized steel for thin-walled internal gears is as follows in terms of mass percentages : C 0.15~0.30%, Mn 0.90~1.40%, P≤0.035%, S 0.015~0.045%, Cr 0.90~1.40%, Al 0.015~0.035%, Si≤0.25%, Ti 0.010~0.030%, Nb 0.02~ 0.04%, O≤0.0015%, N 0.012~0.017%, Ni≤0.20%, Cu 0.10~0.20%, Mo≤0.06%, V≤0.04%, and the rest are Fe and unavoidable impurities. The thin-walled inner ring gear of the present invention does not cause local decrease in hardenability, the fluctuation of material hardenability is small, the subsequent heat treatment parts are uniformly deformed, and the heat treatment deformation of the inner thin-walled ring gear can be effectively controlled.

Description

technical field [0001] The invention belongs to the technical field of metallurgy and ring gear manufacturing, and in particular relates to a Ti-containing carburizing steel for a thin-walled ring gear, a manufacturing method thereof, and a thin-walled ring gear forming method. Background technique [0002] Domestic heavy-duty gearboxes mostly adopt planetary auxiliary box structure. The inner ring gear of the auxiliary box is a thin-walled annular part with an outer diameter of ф277mm, a wall thickness of 22mm, and a width of 104mm. See figure 2 , the roundness and taper are required to be controlled within 0.10mm, the tooth direction fHβ is not greater than 50μm, and the carburizing heat treatment deformation is large. The carburizing steel 20CrMnTiH, which is widely used in the Mn-Cr-Ti series in China, cannot meet the requirements. Among them, GB / T5216 stipulates the mass percentage (%) of material alloy elements: C 0.17~0.22, Si≤0.37, Mn 1.10~1.40, Cr 1.00~1.30, Ti 0.04...

AI Technical Summary

Problems solved by technology

Due to the influence of material chemical composition, metallurgical segregation, forming method and other factors, the metallographic structure formed in each part of the forging billet is difficult to be uniform, and the hardness dispersion is greater than HB10, which makes it difficult to control the heat treatment deformation of the parts in the subsequent carburizing process

Domestically, continuous furnace carburizing + press quenching process is adopted for thin-walled ring parts. The diffusion temperature of carburizing heat treatment process is 870-890°C, the carbon potential is controlled at 0.85%, and the press quenching temperature is 860°C, which is easy to cause deformation of parts

[0006] In summary, the thin-walled internal ring gear materials in the prior art have the following deficiencies: (1) The Ti content in the thin-walled internal ring gear material is high, resulting in large fluctuations in the hardenability of the material, and large particles of TiN

(2) Isothermal normalizing or forging waste heat isothermal normalizing process is adopted for forging billet pretreatment, the structure of each part of the forging is not uniform, and the hardness dispersion is greater than HB10

(3) The continuous furnace carburizing + press quenching process is adopted for thin-walled ring parts. The diffusion temperature and carbon potential of carburizing heat treatment are high, resulting in high residual austenite content on the surface of the part, high press quenching temperature, and large heat treatment deformation.

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