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Rare earth controllable carburizing method for furnace for periodical operation

A technology of periodic operation and carburizing furnace, applied in the direction of metal material coating process, coating, solid diffusion coating, etc., can solve the problem of seldom use and so on

Inactive Publication Date: 2007-07-11
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

How to shorten the carburizing process time, increase the carburizing speed, and reduce energy consumption, the usual method is to increase the carburizing temperature and increase the carbon potential of the furnace gas, but there are certain restrictions due to the constraints of the carburizing workpiece and the characteristics of the steel used. Therefore, it is rarely used in production

Method used

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Examples

Experimental program
Comparison scheme
Effect test

specific Embodiment approach 1

[0004] Specific embodiment one: this embodiment uses well-type gas carburizing furnace or sealed box-type multi-purpose gas carburizing furnace, and its method is realized by the following four stages: 1. Heating and exhaust stage; 2. Intensive infiltration stage I; 3. Strong infiltration stage II; 4. Diffusion stage; when the temperature in the carburizing furnace rises to 920-940°C in the heating and exhaust stage, the hole is closed, and when the diffusion stage is over, the workpiece in the carburizing furnace cools down to 820-860 ℃ can be quenched; when the temperature in the carburizing furnace rises to 820 ℃ during the heating and exhaust stage, start to drop rare earth carburizing agent into the carburizing furnace to make the carbon potential in the carburizing furnace C p From 0.6% at 820°C to 1.45% when the hole is closed, the carburizing time is 80-130 minutes; the carburizing time of the strong infiltration stage I is 2-4 hours, and the carbon potential is C p Fr...

example 1

[0005] Example 1: The active and passive terminal drive helical gears and gearbox gears of the rear axle of a 8-10-ton truck in a factory, the modulus is M8-10 and M4-6, and the depth of the carburized layer is required to be 1.7-2.1mm and 0.6-1.1mm, Material is 20C r MoH or 22C r MoH, the carburizing temperature of the original process is 930°C. Because this material is particularly easy to form thick strips or claw-shaped carbides with poor morphology on the austenite grain boundary or triangular grain boundary of the carburized surface layer, which exceeds the metallographic inspection standard, so only furnace gas can be used. carbon potential C p = 1.0% low carbon potential carburizing, using a standard 105 well carburizing furnace for carburizing, from furnace loading to reaching a carburized layer depth of 1.7mm and 0.6mm or more, the required time is 24 and 7 hours. And adopt the method of the present invention, it only takes 16 hours and 5 hours for the workpiece t...

example 2

[0006] Example 2: Large and medium-sized bearings of a railway vehicle, the material is 20C r NiM. Carburizing of steel requires a carburizing layer depth of 2.7-3.1mm. After carburizing and quenching, the hardness is HRC59-63, and the hardness of the core is HRC38-42. It is carburized in a 180KW well-type carburizing furnace, and the medium is methanol and kerosene. . The furnace gas carbon potential monitoring is an oxygen probe, and the control instrument, that is, the executive instrument, is a carbon potential control intelligent instrument, which is controlled by a computer. When using the conventional one-stage method, the carburizing temperature is 930 ° C, and the furnace gas controls the carbon potential C p = 1.2%, it takes about 30 hours from furnace loading to furnace quenching, and the carburized layer depth is about 2.8mm. Using the method of the present invention under the same carburizing temperature condition, it only takes 20-22 hours to reach a carburizin...

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Abstract

The method of discontinuous running carburizing furnace rare-earth controllable changing carbon potential carburizing was introduced in the invention. It was involved in one kind of rare-earth controllable changing carbon potential carburizing. It is carried out by adding rare-earth cementation agent to the carburizing furnace when the furnace temperature rise to 820 deg.C in the period of air-out, the earbon, potential reduced from 0.6% to 1.45% till close the pore, the carburizing time is 80-120 min, the strong carburizing period I was 2-4h, the carbon potential reduced form 1.45% to 1.25%, the strong carburizing period II was 4-6, the carbon potential reduced from 1.25% to 1.1%. The diffusion period was 6-8h, the carbon potential reduced from 1.1% to 0.8%. Its advantages include advanced the potential of carburizing furnace; increased the carburizing speed; shorten the time of carburizing; the function of rare-earth cementation agent more effective when combined the high carbon potential; shorten the carburizing time more than 30%, power saved 25-35%.

Description

Technical field: [0001] The invention relates to a rare earth controllable variable carbon potential carburizing method for a periodic operation carburizing furnace. Background technique: [0002] Carburizing is a high-energy thermal processing process. Conventional carburizing requires placing the carburized workpiece in a special carburizing furnace heated to 900-950°C, and keeping it warm in the carburizing medium for several to tens of hours. The surface of the workpiece is infiltrated with carbon atoms, and then the workpiece is taken out and quenched so that the surface hardness of the workpiece reaches HRC58~65, so that the surface of the workpiece has high hardness, strength and wear resistance, and at the same time greatly increases the resistance to bending and contact fatigue, so as to ensure that Gears, bearings and other parts are used for a long time. It can be seen that the existing carburizing process not only takes a long time but also has low work efficien...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C23C8/20
Inventor 闫牧夫刘志儒
Owner HARBIN INST OF TECH
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