Manufacturing method of steel for speed reducer gear of electric automobile

Abstract

The invention relates to a manufacturing method of steel for a speed reducer gear of an electric automobile, belongs to the technical field of iron-based alloys, and particularly relates to steel for gears. According to the element composition design related, the steel comprises, by mass, 0.20%-0.35% of C, 0.05%-0.35% of Si, 1.20%-1.60% of Mn, 1.10%-1.50% of Cr, 0.20%-0.50% of Mo, smaller than or equal to 0.035% of S, smaller than or equal to 0.015% of P, smaller than or equal to 0.20% of Cu, smaller than or equal to 0.20% of Ni, 0.010%-0.080% of Al, 0.0060%-0.0260% of N and the balance Fe and inevitable impurities, wherein Al / N is equal to 1.5 to 3.9. The smelting technological process comprises the following steps of pre-treated molten iron and optimized scrap steel, primary smelting in an electric furnace, refining in an LF furnace, vacuum degassing in a VD furnace, continuous casting of square billets, shot blasting of the continuously-cast square billets, heating in a walking beam furnace, descaling with high-pressure water, rolling of the continuous casting billets, surface flaw detection and internal ultrasonic flaw detection of hot-rolled round steel, quality inspection and warehousing. The element components are matched with the smelting process, and the steel meets the requirements of high strength and long fatigue life of the steel for an electric automobile speed reducer. And remarkable advantages are obtained on the aspects of hardenability and grain uniformity.

Description

technical field [0001] The invention belongs to the technical field of iron-based metallurgy, and more relates to a manufacturing method of gear steel. Background technique [0002] Due to the advantages of low noise, zero emission, comfort and cleanliness, electric vehicles are the only way to achieve automation and intelligent development of automobiles. At present, the amount of oil used in the world is increasing, but the amount of oil that can be exploited is decreasing. Therefore, it is an inevitable trend for the development of the automobile industry to replace conventional fuel vehicles with electric vehicles. The pure electric vehicle reducer needs to meet the characteristics of all complex working conditions from low-speed high-torque to high-speed operation. Therefore, the gear of the electric vehicle reducer requires steel to have higher strength and better toughness, which is also in line with the lightweight development of electric vehicles. trend. The exist...

AI Technical Summary

Problems solved by technology

The existing electric vehicle reducer gear steel usually uses steel materials with high alloy content such as SAE8620H and 18CrNiMo7-6. Such steel generally needs to be added with a high content of nickel, resulting in high production costs for the steel.

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