Production process for lightening 22CrMoH gear steel banded structure

A banded structure and production process technology, applied in the production process field of reducing the banded structure of 22CrMoH gear steel, can solve problems affecting the quality of gear steel products, shorten the length of the liquid core and solidification time, reduce element segregation, and reduce the tensile strength. speed effect

Inactive Publication Date: 2019-08-06
HANDAN IRON & STEEL GROUP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the gear steel, it is arranged in parallel along the rolling direction, distributed in layers, and shaped like striped ferrite and pearlite structures; it is generally believed that the root cause of the banded structure is element segregation. From the data obtained so far It can be seen that the research on banded structure in the industry mainly focuses on the formation mechanism and control measures of banded structure in low-carbon steel with low alloy content. The main reason for the structure, the elimination of the banded structure is mainly to eliminate the micro-segregation of C, Mn and other elements, to speed up the cooling rate of molten steel during solidification, to reduce the degree of segregation of C and Mn elements, and to reduce the concentration difference of segregation , using higher slab soaking temperature and time to promote the diffusion rate of C, Mn and other elements; but it is often difficult to achieve the time and temperature required for the homogenization of elements, especially Mn elements, in actual production. Therefore, the current metallurgical Most of the banded structure of gear steel produced by the enterprise has a grade ≥ 3.0, which seriously affects the product quality of gear steel

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] Production of φ90mm22CrMoH gear steel, through primary smelting in converter, LF refining, RH refining, continuous casting into a rectangular billet, the size is 200*200mm, the weight percentage of the chemical composition of the billet is: C: 0.21%, Si: 0.27%, Mn: 0.80% , Cr: 1.08%, Mo: 0.40%, P: 0.009%, S: 0.003%, Als: 0.024% [O] 0.00010%, and the rest are iron and unavoidable impurity elements. Converter process adopts double slag process for smelting, slag dumping and slag replenishment operation in the middle, P content at the end point is controlled below 0.008wt%, continuous casting adopts dynamic soft reduction control and mold electric stirring, end electric stirring double electric stirring process, molten steel Pouring superheat degree ≤30°C, casting speed 1.0m / min, mold electromagnetic stirring 340A / 3HZ, terminal electromagnetic stirring 240A / 6HZ, billet stacking to avoid wind and slow cooling, billet center segregation is controlled at 0.5 level;

[0026] T...

Embodiment 2

[0029] Production of φ70mm22CrMoH gear steel, through primary smelting in converter, LF refining, RH refining, continuous casting into a rectangular billet, the size is 200*200mm, the weight percentage of the chemical composition of the billet is: C: 0.23%, Si: 0.23%, Mn: 0.75% , Cr: 1.10%, Mo: 0.42%, P: 0.015%, S: 0.010%, Als 0.026% [O] 0.00006%, and the rest are iron and unavoidable impurity elements. Converter process adopts double slag process for smelting, slag dumping and slag filling operation in the middle, P content at the end point is controlled at 0.007wt%, continuous casting adopts dynamic soft reduction control and mold electric stirring, terminal electric stirring double electric stirring process, molten steel pouring Superheating degree ≤ 30°C, casting speed 1.1m / min, mold electromagnetic stirring 350A / 3HZ, terminal electromagnetic stirring 260A / 6HZ, billet stacking to avoid wind and slow cooling, and the center segregation of billet is controlled at 0.5 level; ...

Embodiment 3

[0033]Production of φ65mm22CrMoH gear steel, through primary smelting in converter, LF refining, RH refining, continuous casting into a rectangular billet, the size is 200*200mm, the weight percentage of the chemical composition of the billet is: C: 0.22%, Si: 0.25%, Mn: 0.79% , Cr: 1.05%, Mo: 0.37%, P: 0.009%, S: 0.003%, Als: 0.024% [O] 0.00008%, and the rest are iron and unavoidable impurity elements. Converter process adopts double slag process for smelting, slag dumping and slag filling operation in the middle, P content at the end point is controlled at 0.008wt%, continuous casting adopts dynamic soft reduction control and mold electric stirring, terminal electric stirring double electric stirring process, molten steel pouring The degree of superheat is ≤30°C, the casting speed is 1.2m / min, the electromagnetic stirring of the mold is 360A / 3HZ, and the electromagnetic stirring of the end is 260A / 6HZ. The heating furnace heats the steel billet to 1130-1180°C, and the holdin...

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Abstract

The invention relates to a production process for lightening 22CrMoH gear steel banded structure. The production method includes converter smelting, LF refining, RH refining, continuous casting, heating and rolling processes. In the converter smelting process, The end point P content is controlled below 0.008 wt%. In the RH refining process, soft blowing time is more than or equal to 12 min afterthe RH refining to ensure that inclusions float up and chemical components are even and reduce segregation caused by uneven chemical components. The continuous casting process ensures that molten steel casting superheat rate is less than or equal to 30 DEG C. The production process of the invention effectively controls the center segregation of a gear steel casting blank and increases a ratio of equiaxed crystals. Low superheat rate and low casting speed shorten the length of a liquid core and solidification time and reduce element segregation, thereby reducing a grade of a banded structure.

Description

technical field [0001] The invention relates to a production process of gear steel, in particular to a production process for reducing the strip structure of 22CrMoH gear steel. Background technique [0002] Cr-Mo series gear steel is a high-standard automotive gear steel imported from the Japanese Iron and Steel Industry Standard JIS in order to meet the needs of the development of the automotive industry in my country. There are mainly SCM415H, SCM420H, and SCM822H, of which the largest domestic demand is SCM822H and SCM420H The two steel grades, SCM822H is 22CrMoH in the national standard, which is mainly used for the production of main reduction gears for heavy-duty trucks. [0003] Gear steel is one of the key materials that are used in large amounts and require high requirements in automobile materials. It not only affects the service life and energy consumption indicators of automobiles, but also plays a vital role in meeting safety, environmental protection and comfor...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21C5/36C21C7/072C21C7/076C21C7/10B22D11/115B22D11/12B22D11/18C21D8/00C22C38/02C22C38/04C22C38/06C22C38/22
CPCB22D11/115B22D11/1206B22D11/122B22D11/182C21C5/36C21C7/072C21C7/076C21C7/10C21D8/005C22C38/02C22C38/04C22C38/06C22C38/22Y02P10/20
Inventor 肖振会许海平徐斌肖国华王利伟鲁晓旭卢巧婷
Owner HANDAN IRON & STEEL GROUP
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