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Isothermal normalizing heat treatment process

A normalizing heat treatment and process technology, applied in heat treatment furnaces, heat treatment equipment, manufacturing tools, etc., can solve the problems that the cooling rate cannot be kept consistent, it is difficult to achieve uniform cooling of the gear shaft, and affect the machining and mechanical properties of the workpiece.

Active Publication Date: 2019-10-18
BEIJING RES INST OF MECHANICAL&ELECTRICAL TECH
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  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in the existing isothermal normalizing process, the workpieces are piled up in the cooling bellows for continuous cooling during the cooling process to transform the austenite structure into ferrite and pearlite structures after the workpiece is austenitized for a period of time. To the holding temperature, the cooling rate of the upper workpiece and the lower workpiece cannot be kept the same, which is obviously difficult to achieve uniform cooling of the gear shaft, and the generated ferrite and pearlite structures are not uniform, which affects the machining and mechanics of the workpiece performance

Method used

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Embodiment Construction

[0032] An isothermal normalizing process, which can transform the structure from austenite to uniform ferrite and pearlite after cooling for a certain period of time after the workpiece is austenitized. At the same time, it can rationally use the waste heat after rolling to save energy and Process costs, which include:

[0033] Step 1, heating the cylindrical billet in an induction heating furnace to transform the original annealed ferrite and pearlite structure into austenite;

[0034] Put the cylindrical blank of low-carbon and low-alloy carburizing steel in the induction heating furnace and heat it to 1100-1300°C, and determine the holding time according to the diameter of the workpiece, generally 10-30min, so that it can be transformed from the original annealed ferrite And the pearlite structure is transformed into austenite, so that the blank is austenitized and the composition is uniform, and the deformation resistance of the cylindrical blank is reduced, which is conve...

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Abstract

The invention discloses an isothermal normalizing heat treatment process. Through re-generating of austenite, the workpiece banded structure is reduced, the generated structure is more uniform, the machining property of the workpiece is improved, the workpiece mechanical property is improved, meanwhile, waste heat after rolling is used, electric energy is saved, and production cost is reduced.

Description

technical field [0001] The invention belongs to the technical field of heat treatment of metal parts, in particular to an isothermal normalizing heat treatment process. Background technique [0002] The gear shaft plays an extremely important role in the car gearbox. Because the stress state is very complex when it is in service, it is generally required to have good strength and toughness, good fatigue resistance and wear resistance. Generally speaking, the gear shaft is made of low-carbon low-alloy carburized steel, and its manufacturing process is as follows: blanking, induction heating, cross wedge rolling or forging, normalizing, shot blasting, rough machining, carburizing and quenching, Tempering, finishing, grinding, random inspection and storage. In the above process, the main purposes of normalizing are: to obtain suitable hardness for subsequent machining operations; to obtain reasonable ferrite and pearlite structures to prepare for carburizing and quenching. T...

Claims

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Application Information

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IPC IPC(8): C21D1/28C21D9/28C21D9/32
CPCC21D1/28C21D9/28C21D9/32C21D2211/005C21D2211/009
Inventor 罗平李贤君张文良王劲巫小林周彤
Owner BEIJING RES INST OF MECHANICAL&ELECTRICAL TECH
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