Gear steel 20CrMoSH and technology for improving hardenability stability thereof

Abstract

The invention discloses gear steel 20CrMoSH and a technology for improving the hardenability stability thereof. The technology comprises the procedures of converter smelting, LF refining, RH refining,continuous casting, heating and rolling. The gear steel is prepared from the chemical components, by weight, 0.19%-0.21% of C, 0.20%-0.26% of Si, 0.64%-0.70% of Mn, 1.00%-1.06% of Cr, 0.15%-0.21% ofMo, 0.015%-0.025% of S, smaller than or equal to 0.018% of P, 0.015%-0.025% of Als, smaller than or equal to 0.03% of Ni, smaller than or equal to 0.03% of Cu, smaller than or equal to 0.0015% of O and the balance Fe and unavoidable impurities. According to the gear steel 20CrMoSH which is produced through the method and has the diameter phi ranging from 28 mm to 50 mm, the hardenability J1.5 ranges from 40 HRC to 45 HRC, the hardenability J5 ranges from 37 HRC to 42 HRC, the hardenability J9 ranges from 28 HRC to 33 HRC, and the maximum discrete value of the hardenability of the steel in thesame furnace is not larger than 3 HRC. The heat-treatment deformation of a gear can be significantly reduced by means of high-stability hardenability, and therefore the meshing precision of the gear is improved. The method is low in cost and high in production efficiency, and the product has the advantages that the hardenability is stable, the gear heat-treatment deformation is small, and the machined gear is high in meshing precision and low in service life.

Description

technical field [0001] The invention relates to a gear steel and a production process thereof, in particular to a gear steel 20CrMoSH and a production process for improving its hardenability stability. Background technique [0002] With the rapid development of the automobile industry, the market demand for vehicle gears is increasing day by day, and the gear transmission is gradually transforming and upgrading to a simpler and lighter structure with high speed, low noise, high efficiency, high precision and long life. CrMo series gear steel has stable hardenability, and the processed gear can withstand huge alternating loads and impact loads. It has good strength, toughness, wear resistance, small deformation, high precision, and low noise. Therefore, CrMo Because of its excellent comprehensive performance, the gear steel has been widely used in the field of heavy-duty gears. [0003] 20CrMoSH is currently the leading product of CrMo series gear steel in China. The heavy-d...

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Problems solved by technology

The design scope of the chemical composition C, Si, Mn, Ti, and Cr in this invention is relatively wide, which is not conducive to narrow hardenability control; the control of the P element that affects segregation is too high, which is easy to cause composition segregation and cause hardenability fluctuations; at the same time, the Cr element The design is too high, and the addition of B and W elements, the cost is high; the hardenability only guarantees the two positions of J9 and J15

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