Automotive boron-containing high-grade gear steel and production process thereof

Abstract

The invention discloses automotive boron-containing high-grade gear steel and a production process thereof. The gear steel is prepared from the following components in percentage by weight: 0.15 to 0.20 percent of C, 0.15 to 0.40 percent of Si, 1.00 to 1.30 percent of Mn, 1.00 to 1.30 percent of Cr, 0.0005 to 0.0030 percent of B, 0 to 0.030 percent of P, 0 to 0.035 percent of S, 0 to 0.30 percent of Cu, 0.12 to 0.18 percent of Ni, 0.020 to 0.045 percent of Al, 0.015 to 0.035 percent of Ti and the balance of Fe and inevitable impurity. The production process comprises working procedures of smelting, continuous casting, rolling and the like. According to the automotive boron-containing high-grade gear steel, through adding elements of the Al, the Ti and the Ni and adopting a nitrogen fixation and boron protection process, optimization measures of other processes of a continuous casting process and the like are ameliorated; comprehensive properties of the purity, the hardenability, the grain size, the texture homogeneity, the impact toughness and the like of a material are greatly improved.

Description

technical field [0001] The invention belongs to the field of metallurgy, and relates to a high-grade boron-containing gear steel for automobiles and a production process thereof. Background technique [0002] Boron-containing gear steel 18CrMnBH is mainly used to make gearbox gears for Volvo, Mercedes-Benz, Keith Bauer and other models. This steel grade has strict requirements on hardenability, impact toughness, non-metallic inclusions and other items. It is one of the steel grades with the highest quality requirements, the most inspection items and the most difficult production among the existing gear steel grades. At present, only a few special steel factories use die casting for production, and the quantity is small and the quality is unstable. [0003] Boron has been added to steel for more than 50 years as the most effective trace element to improve hardenability, but the development of boron steel is slow and tortuous. The purpose of adding boron to steel is mainly t...

AI Technical Summary

Problems solved by technology

Since the traditional process cannot effectively control the effective boron content in 18CrMnBH, the hardenability is unstable, and the comprehensive performance indicators such as impact toughness and non-metallic inclusions are also difficult to meet the requirements of the automobile factory. Therefore, how to ensure the effective boron content of this steel type It has become a major difficulty in the industry to improve hardenability and improve performance indicators such as material purity, grain size, structure uniformity, and impact toughness.

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