A kind of gear steel and its production method

Abstract

The invention discloses gear steel and production method thereof. The gear steel comprises the chemical components in percentage by weight: 0.25 to 0.32 percent of carbon, 0.25 to 0.30 percent of silicon, 1.20 to 1.40 percent of manganese, less than or equal to 0.030 percent of phosphorus, 0.025 to 0.045 percent of sulfur, 1.05 to 1.25 percent of chromium, 0.05 to 0.10 percent of vanadium, 0.009 to 0.0120 percent of nitrogen, less than or equal to 0.0015 percent of oxygen and the balance of iron. Technological parameters of steel billet heating, steel billet rolling and cooling are controlled, so that crystal particles of the gear steel are refined, and the fatigue performance of the gear steel is not affected.

Description

technical field [0001] The invention belongs to the technical field of metallurgical manufacture, and in particular relates to a gear steel and a production method thereof. Background technique [0002] Gear steel is an important mechanical component, especially the gear steel used in automobiles. When the gears on the automobile are working, the root of the tooth is prone to fatigue fracture under the action of bending stress, and the surface metal is easily peeled off under the action of contact stress. Therefore, it is required Steel must have good properties. The main factors affecting the performance of gear steel are hardenability, cleanliness and grain size. At present, by precisely controlling the content and uniformity of the chemical composition, the hardenability is improved, and the entire cross-section of the steel piece has uniform mechanical properties, reducing deformation and cracking; by reducing the oxygen content in the gear steel, the gear steel is impr...

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Problems solved by technology

The three inventions of authorized announcement number CN 102703834 B, authorized announcement number CN 102517521 B and application publication number CN102605260A refine the grain size by adding Al element, but Al element is easy to react with oxygen element in steel to form oxide inclusions and It is not easy to remove all of them, which will affect the cleanliness of the gear steel and greatly reduce the fatigue performance of the gear steel

[0004] Chinese invention patent (authorization announcement number CN 102400052 B authorization announcement date 2013.05.15) discloses a narrow hardenability gear steel, adding medium Ti element to fix nitrogen and refine grain, and through 1) top-bottom composite blowing converter primary 2) Ladle deoxidation alloying; 3) LF refining; 4) RH refining; 5) The gear steel obtained by the continuous casting production method has the characteristics of high hardenability and narrow end hardenability, but Ti TiN particles form TiN particles with N elements in steel, and TiN particles are in the shape of rhomboids. If they exist in steel for a long time, they will easily become a source of fatigue stress, which is not conducive to the improvement of fatigue performance of gear steel.

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