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Rare earth controllable carburizing method for furnace for periodical operation

A periodic operation, carburizing furnace technology, applied in the direction of metal material coating process, coating, solid diffusion coating, etc., can solve the problem of rarely used

Inactive Publication Date: 2005-07-27
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] Embodiment 1: This embodiment uses a well-type gas carburizing furnace or a sealed box-type multi-purpose gas carburizing furnace, and its method is realized by the following four stages: 1. The heating and exhausting stage; 2. The strong infiltration stage 1; 3. Strong infiltration stage II; 4. Diffusion stage; when the temperature in the carburizing furnace rises to 920-940 °C in the heating and exhausting stage, the hole is closed, and when the diffusion stage is over, the workpiece in the carburizing furnace is cooled to 820-860 °C ℃ can be quenched; when the temperature in the carburizing furnace rises to 820 ℃ in the heating and exhausting stage, the rare earth carburizing agent will be dripped into the carburizing furnace to make the carbon potential C in the carburizing furnace. p From 0.6% at 820°C to 1.45% when the hole is closed, the carburizing time is 80 to 130 minutes; the carburizing time of the strong infiltration stage I is 2 to 4 hours, and the carbon p...

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 modules are 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. The material is 20CrMoH or 22CrMoH, and the carburizing temperature of the original process is 930 ℃. Because the material is particularly easy to form thick strip-shaped or claw-shaped carbides with poor morphology on the austenite grain boundaries or triangular grain boundaries of the carburized surface layer, which exceeds the metallographic inspection standard, only furnace gas can be used. carbon potential C p =1.0% low carbon potential carburizing, using standard 105 well type carburizing furnace for carburizing, from loading the furnace to reaching the carburized layer depth of 1.7mm and 0.6mm or more, the time required for quenching is 24 and 7 hours. With the method of the present invention, the workpiece only takes 16 ...

example 2

[0006] Example 2: A large and medium bearing of a railway vehicle, the material is 20CrNiM. For steel carburization, the depth of carburizing layer is required to be 2.7~3.1mm, the hardness after carburizing and quenching is HRC59~63, and the hardness of the core is HRC38~42. The carburizing treatment is carried out 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. p =1.2%, it takes about 30 hours from loading to quenching, and the carburized layer is about 2.8mm deep. Using the method of the invention under the same carburizing temperature conditions, it only takes 20 to 22 hours to reach the carburized layer depth of more than 2.8 mm, the working hours are reduced by 8 to 10 hours, the infiltration rate is increased by 26 to 33...

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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 and variable carbon potential carburizing method in a periodic operation carburizing furnace. Background technique: [0002] Carburizing is a high-energy-consuming thermal processing process. Conventional carburizing requires placing the carburized workpiece in a special carburizing furnace heated to 900-950 °C, and keeping it in the carburizing medium for several hours 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 can reach HRC58-65, so that the workpiece surface has high hardness, strength and wear resistance, and at the same time, the resistance to bending and contact fatigue is greatly increased. 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 efficiency an...

Claims

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Application Information

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