Steel for cold extrusion gear shaft and preparation method thereof

Abstract

The invention discloses steel for a cold extrusion gear shaft and a preparation method of the steel. The steel comprises the following chemical components in percentage by mass: 0.19%-0.21% of C, 0.15%-0.25% of Si, 1.11%-1.20% of Mn, less than or equal to 0.015% of P, 0.015%-0.025% of S, 1.03%-1.10% of Cr, 0.035%-0.050% of Al, less than or equal to 0.20% of Cu, less than or equal to 0.010% of Ti, 0.01%-0.03% of V, less than or equal to 0.010% of Nb, less than or equal to 0.010% of Sn, less than or equal to 0.0010% of B, less than or equal to 2.0 ppm of H, 110ppm-140ppm of N and the balance of Fe. Through chemical component design and an innovative production process, the gear steel is high in size precision, excellent in inner and outer surface quality and uniform and compact in structure after being subjected to cold pressing forming by a user, the fatigue life of the gear steel is 40% or above longer than that of a common hot forging gear shaft, meanwhile, subsequent surface finish machining is reduced, and the comprehensive manufacturing cost is reduced by 20% or above. The gear shaft steel produced according to the invention has the characteristics of high precision, high rigidity, uniform structure, excellent surface quality, low energy consumption, less pollution, long fatigue life and the like.

Description

Technical field: [0001] The invention relates to gear steel in the iron and steel industry, in particular to a cold extrusion gear shaft steel and a preparation method thereof. Background technique: [0002] Gear is a mechanical element that continuously meshes with gears on the rim to transmit motion and power, and is widely used in mechanical transmission and mechanical fields. Gears have been developed for thousands of years, and the materials range from bronze and cast iron to modern steel and alloys. The main failure modes of gears are tooth surface wear and gluing. For this reason, surface carburized steel is used to manufacture gears to improve the hardness and wear resistance of tooth surfaces. [0003] The European standard EN 10084 "Carburizing Steel" stipulates that C of 20MnCr5: 0.17%-0.22%, Si≤0.40%, Mn: 1.10%-1.40%, P≤0.025%, S: 0.020%-0.040%, Cr: 1.00%-1.30%. At present, European and American countries mostly use 20MnCr5 material to manufacture automobile t...

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Problems solved by technology

[0004] The technical problem to be solved in the present invention is to provide a kind of steel for cold extrusion gear shaft and its preparation method in view of the problems existing in the existing 20MnCr5 steel product and its production process

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