Low-carbon CrNiMo gear steel and preparation method thereof

Abstract

The invention provides low-carbon CrNiMo gear steel and a preparation method thereof. The low-carbon CrNiMo gear steel comprises the following chemical components in percentage by weight: 0.15 to 0.21 percent of C, 0.15 to 0.30 percent of Si, 0.60 to 0.90 percent of Mn, 1.55 to 1.80 percent of Cr, 1.50 to 1.70 percent of Ni, 0.25 to 0.35 percent of Mo, 0.025 to 0.038 percent of Al, less than or equal to 0.20 percent of Cu, less than or equal to 0.020 percent of P, less than or equal to 0.010 percent of S, 0.0075 to 0.0130 percent of N and the balance being iron and other inevitable impurities. The preparation method comprises the steps of electric furnace smelting, LF refining, VD vacuum treatment and continuous casting. According to the invention, total oxygen content in molten steel is controlled by controlling tapping carbon; alloy components are basically controlled in place in an electric furnace tapping process, and LF fine adjustment is conducted; a proper amount of slag is added during tapping, an Al wire is fed in place in an early stage of LF, soft blowing is only conducted in the middle and later stages, and the components are not adjusted any more; and weak calcium treatment before VD vacuumizing denatures inclusions, nitrogen is increased through bottom blowing of the nitrogen in a vacuum state, and soft blowing time after VD vacuum breaking is reasonably controlled to ensure that the inclusions fully float upwards and are adsorbed by the slag, so that cleanliness of the molten steel is improved, and quality of the inclusions of a product is improved.

Description

technical field [0001] The invention belongs to the field of steel for gears, and more specifically relates to a low-carbon CrNiMo gear steel and a preparation method thereof. Background technique [0002] As the requirements for the use of wind power gear mechanical parts are getting higher and higher, especially in offshore and high-altitude desert areas, the cost of maintenance and maintenance is high. Sometimes the cost of replacing parts is even equivalent to the cost of materials. In order to ensure the smooth use of wind power gear boxes Years have not changed, and downstream users have increasingly stringent standards for inclusions in gear steel for wind power. [0003] At present, the cleanliness of common low-carbon CrNiMo series gear steels is difficult to meet the needs of the wind power industry under large loads and complex environments. With the decline of the country's subsidy bonus for the wind power industry, the enthusiasm of downstream users to rush to ...

AI Technical Summary

Problems solved by technology

In terms of cleanliness and inclusions in molten steel, once improperly controlled, it is very easy to become the source of fatigue cracks during the use of steel and reduce the service life of steel

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