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A kind of cold forming method of cr-ni carburizing steel and parts containing nb for cold forming

A technology of cold forming and carburizing steel, applied in the furnace type, heat treatment equipment, furnace and other directions, can solve the problem of resistance to cold extrusion forming, grain growth in carburizing treatment, etc., to avoid heat treatment deformation aggravated, Improve the plasticity and toughness, the effect of uniform internal and external organization

Active Publication Date: 2022-03-25
DONGFENG COMML VEHICLE CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] Chinese invention patent (patent number CN201810775502.X) discloses the application of a Nb, Ti composite microalloyed high-temperature pinhole carburized heavy-duty gear steel, Nb, Ti composite microalloyed into special carburized steel for non-cold press forming , the billet undergoes spheroidizing annealing or complete annealing process, the hardness range is HB135~145, which cannot solve the problem of cold extrusion resistance, and the grain growth trend of carburizing treatment

Method used

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  • A kind of cold forming method of cr-ni carburizing steel and parts containing nb for cold forming
  • A kind of cold forming method of cr-ni carburizing steel and parts containing nb for cold forming
  • A kind of cold forming method of cr-ni carburizing steel and parts containing nb for cold forming

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Embodiment 1

[0037] The inner ring gear of a heavy-duty gearbox sub-box is produced by carburizing, and the depth of carburizing process requires 0.8-1.1mm.

[0038] Cr-Ni carburizing steel for cold forming containing Nb: chemical composition mass percentage includes: C 0.14%, Mn 0.75%, P0.016%, S 0.025%, Cr 1.00%, Al 0.020%, Nb 0.06%, O 10ppm, N 120ppm, Si 0.20%, Ni 1.20%, Cu 0.12%, Mo 0.05%, V 0.03%, and the rest are Fe and unavoidable impurities.

[0039]Forming process of the present invention: Nb-containing cold forming with Cr-Ni carburizing steel blanking induction heating 1100°C, after the ring is formed, the temperature is not lower than 860°C, sent to a 950°C isothermal normalizing furnace, kept for 1 hour, cooled to 650°C for heat preservation 2.5h, shot peening to remove scale. Parts are heated to 760°C, held for 4 hours, cooled to 700°C for 4 hours; heated to 760°C, held for 4 hours, cooled to 700°C for 4 hours; heated to 760°C, held for 4 hours, cooled to 700°C for 4 hours, ...

Embodiment 2

[0044] The inner ring gear of a heavy-duty gearbox sub-box is produced by carburizing, and the carburizing process requires a layer depth of 0.8-1.1mm.

[0045] Cr-Ni carburizing steel for cold forming containing Nb: chemical composition mass percentage includes: C 0.10%, Mn 1.10%, P0.016%, S 0.025%, Cr 1.20%, Al 0.020%, Nb 0.050%, O 10ppm, N 120ppm, Si 0.10%, Ni 1.40%, Cu 0.18%, Mo 0.05%, V 0.03%, and the rest are Fe and unavoidable impurities.

[0046] Forming process of the present invention: Nb-containing cold forming with Cr-Ni carburizing steel blanking induction heating 1250°C, the temperature after rolling ring forming is not lower than 860°C, sending it into an isothermal normalizing furnace at 1000°C, holding for 2 hours, cooling to 700°C for heat preservation 2h, shot peening to remove scale. Parts are heated to 780°C, held for 2 hours, cooled to 680°C for 2 hours; heated to 780°C, held for 2 hours, cooled to 680°C for 2 hours; heated to 780°C, held for 2 hours, co...

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Abstract

The invention discloses a cold forming method of Cr-Ni carburizing steel and parts containing Nb for cold forming. By reducing the content of C and reducing the content of spherical pearlite after spheroidizing annealing, the hardness of the blank is effectively controlled; adding high content Ni, Improve the plasticity and toughness of ferrite in the blank, so that deformation microcracks are not easy to appear inside and on the surface of the part during cold forming; using the solid solution characteristics of Nb, N, and C in steel, it is partially analyzed at the austenitization temperature of 1100-1250 ° C , the steel grains can be kept from coarsening at the forging temperature; NbN / NbC is completely precipitated to ensure that the grains are finer than grade 7, and no intercooling treatment is required. The pre-oxidation adopts segmental control to activate the surface of the workpiece, reduce the temperature difference between the inside and the outside, and make the internal and external heating more uniform. The internal structure of the part starts repeated crystallization, making the internal and external structure more uniform, and avoiding the heat treatment deformation caused by the sharp rise in temperature; reduce the quenching of Ni-containing steel parts The surface retains austenite, and the surface hardness is not less than HRC61.

Description

technical field [0001] The invention belongs to the technical field of metallurgy and cold forming of parts, and in particular relates to a Cr-Ni carburizing steel for cold forming containing Nb and a cold forming method of parts. Background technique [0002] Cylindrical gears and ring parts of heavy-duty gearboxes are formed by cold extrusion, and the local deformation is large during molding, resulting in uneven cross-sectional deformation, and the grains are easy to coarsen during subsequent carburizing heat treatment. At present, domestic cold extrusion forming parts widely adopt carburizing steel specified in GB / T5216. The blank is subjected to spheroidizing annealing or complete annealing process, and the hardness range is HB135~145. When cold extrusion forming, the resistance is large, it is not easy to form, and it is partially deformed. Large areas are prone to internal micro-cracks. In addition, for cold forming parts adopting continuous furnace carburizing or co...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/04C22C38/06C22C38/48C22C38/02C22C38/42C22C38/44C22C38/46C22C33/06C21D1/28C21D8/00C21D1/32C21D1/18C23C8/22C23F17/00B23P15/14C21D9/32
CPCC22C38/04C22C38/06C22C38/48C22C38/02C22C38/42C22C38/44C22C38/46C22C38/001C22C33/06C21D1/28C21D8/005C21D1/32C21D1/18C23C8/22C23F17/00B23P15/14C21D9/32C21D2211/009
Inventor 皇百红陈郧张宇刘昂仲大伟
Owner DONGFENG COMML VEHICLE CO LTD