阅读说明：本技术 合金钢齿轮的热处理方法 (Heat treatment method of alloy steel gear ) 是由 杨名旗 于 2018-06-27 设计创作，主要内容包括：本发明提供一种合金钢齿轮的热处理方法,是将合金钢齿轮采用碳氮共渗在可气氛条件下进行热处理,包括碳氮共渗、淬火、回火工艺,其是将合金钢齿轮经清洗烘干后,置于可控气氛装置中按如下方法处理：1)排气加热升温2)强渗处理；3)扩散阶段,4)降温处理,5)均温处理,6)油淬处理,7)回火加热处理,8)最后空冷至室温,得产品。其是根据现有20CrMnTi齿轮表面热处理中的不足,提供一种安全适用、易于操作,可有效控制工件变形、提高其加工精度的碳氮共渗可控气氛热处理工艺方法。(The invention provides a heat treatment method of an alloy steel gear, which is to carry out heat treatment on the alloy steel gear under the condition of atmosphere by adopting carbonitriding, comprises the processes of carbonitriding, quenching and tempering, and is to place the alloy steel gear in a controllable atmosphere device after being cleaned and dried according to the following method: 1) exhausting, heating and raising the temperature, and 2) strongly permeating; 3) and (3) a diffusion stage, namely 4) cooling treatment, 5) temperature equalization treatment, 6) oil quenching treatment, 7) tempering heating treatment, and 8) finally air cooling to room temperature to obtain the product. The carbonitriding controllable atmosphere heat treatment process method is safe, applicable and easy to operate, can effectively control the deformation of a workpiece and improve the processing precision of the workpiece according to the defects in the surface heat treatment of the existing 20CrMnTi gear.)

1. A heat treatment method of alloy steel gear, the alloy steel gear adopts carbonitriding to carry on the heat treatment under the controllable atmosphere condition, including carbonitriding, quenching, tempering process, its characteristic is to put the alloy steel gear into the controllable atmosphere apparatus after washing and drying according to the following method to process:

1) heating the exhaust gas to 840-860 ℃, keeping the constant temperature for 40-50 min, and controlling the carbon potential in the device to be 0.95-1.05% in the period;

2) strong infiltration treatment, wherein the strong infiltration time is 300min, and the carbon potential in the device is controlled to be 0.95-1.05% in the period;

3) a diffusion stage, wherein the diffusion time is 55-65min, and the carbon potential in the device is controlled to be 0.75-0.85% in the diffusion stage;

4) cooling to 810 and 830 ℃, and controlling the carbon potential in the device to be 0.75-0.85% in the period;

5) carrying out temperature equalization treatment for 55-65min, and controlling the carbon potential in the device to be 0.75-0.85% in the period;

6) oil quenching treatment, wherein the oil quenching temperature is 100-;

7) tempering and heating treatment, wherein the tempering and heating treatment is carried out to 180 ℃ with the tempering and heating temperature kept for 150 min with the tempering and heating treatment;

8) finally, air cooling to room temperature to obtain the product.

2. A heat treatment method for alloy steel gears according to claim 1 characterized in that the controlled atmosphere is a nitrogen-based atmosphere formulated from nitrogen, methanol, ammonia, propane.

3. A heat treatment method for alloy steel gears according to claim 1 characterized in that the carbonitriding, quenching and tempering steps are performed in a controlled atmosphere furnace.

4. The heat treatment method for an alloy steel gear according to claim 1, wherein the alloy steel gear is a low carbon alloy steel gear.

5. The heat treatment method for alloy steel gears according to claim 1 wherein the air cooling is natural or air cooling in air.

Technical Field

The invention relates to a heat treatment process method of a gear, in particular to a heat treatment method of an alloy steel gear.

Background

The gear is one of the most critical parts in a transmission mechanism of the gearbox, bears the impact load in the transmission process, and the tooth surface is easy to generate fatigue pitting in the meshing transmission process. Along with the requirements of the gearbox on transmission stability, noise and the like are higher, the requirements on the machining process of the gear, particularly the heat treatment process are also higher. The low-carbon alloy steel 20CrMnTi has good cutting processing performance, high tooth surface hardness can be obtained after surface carburization treatment, and the center has enough toughness and higher bending fatigue resistance. The 20CrMnTi material has high gear bearing capacity and long service life. However, the conventional carburizing heat treatment in a shaft gas carburizing furnace inevitably causes deformation of the gear. And although the carburization treatment can make the surface of the gear obtain high carbon concentration, and after quenching and tempering treatment, the surface hardness, the wear resistance and the fatigue strength can be improved, but because the temperature required by carburization is higher, austenite grains are coarse, and more retained austenite exists, the wear resistance of the gear is reduced, and the deformation is larger.

Disclosure of Invention

The invention provides a heat treatment method of an alloy steel gear, which is a safe and applicable carbonitriding controllable atmosphere heat treatment process method which is easy to operate, can effectively control the deformation of a workpiece and improve the processing precision of the workpiece according to the defects in the existing 20CrMnTi gear surface heat treatment.

The invention relates to a heat treatment method of an alloy steel gear, which is to carry out heat treatment on the alloy steel gear under the condition of atmosphere by adopting carbonitriding, comprises the processes of carbonitriding, quenching and tempering, and is to place the alloy steel gear in a controllable atmosphere device after being cleaned and dried according to the following method:

1) heating the exhaust gas to 840-860 ℃, keeping the constant temperature for 40-50 min, and controlling the carbon potential in the device to be 0.95-1.05% in the period;

2) strong infiltration treatment, wherein the strong infiltration time is 300min, and the carbon potential in the device is controlled to be 0.95-1.05% in the period;

3) a diffusion stage, wherein the diffusion time is 55-65min, and the carbon potential in the device is controlled to be 0.75-0.85% in the diffusion stage;

4) cooling to 810 and 830 ℃, and controlling the carbon potential in the device to be 0.75-0.85% in the period;

5) carrying out temperature equalization treatment for 55-65min, and controlling the carbon potential in the device to be 0.75-0.85% in the period;

6) oil quenching treatment, wherein the oil quenching temperature is 100-;

7) tempering and heating treatment, wherein the tempering and heating treatment is carried out to 180 ℃ with the tempering and heating temperature kept for 150 min with the tempering and heating treatment;

8) finally, air cooling to room temperature to obtain the product.

The heat treatment method of the alloy steel gear is characterized in that the controllable atmosphere is a nitrogen-based atmosphere prepared from nitrogen, methanol, ammonia gas and propane.

The carbonitriding, quenching and tempering procedures are all completed in a controllable atmosphere furnace.

According to the heat treatment method of the alloy steel gear, the alloy steel gear is a low-carbon alloy steel gear; particularly, low-carbon alloy steel 20CrMnTi gears are preferred.

The air cooling is natural or air cooling in the air.

The invention finishes the carbonitriding and quenching controllable atmosphere heat treatment of the parts through the steps, because the carbonitriding temperature is lower, the grain growth tendency is small, the nitrogen-containing martensite, the residual austenite and the carbonitride are obtained after quenching, the grain is fine and the deformation is small, the wear resistance of the nitrogen-containing martensite and a small amount of nitride obtained after the heat treatment of the gear parts is better than that of a carburized structure, and simultaneously, the core structure of the gear parts is low-carbon martensite and ferrite, so that the core part of the gear parts can have higher strength and impact toughness. The surface hardness of the low-carbon alloy steel gear part prepared by the method can reach HRC58-62 through testing, and the depth of the infiltrated layer is 0.8-0.9 mm.

The controllable atmosphere is a nitrogen-based atmosphere prepared from nitrogen, methanol, ammonia and propane in proportion, and the nitrogen mainly plays a role in anti-oxidation protection.

In the invention, nitrogen, methanol, ammonia and propane in a certain proportion are introduced into a controlled atmosphere furnace, and the methanol and the propane are subjected to fission reaction at high temperature to form a nitrogen-based atmosphere with a certain carbon potential in the furnace; the carbon potential in the furnace is controlled by adjusting the gas proportion and the input amount.

All the procedures of carbonitriding, quenching, tempering and the like are completed in a controllable atmosphere furnace, and the method has the advantages of safety, applicability, economy, energy conservation, easy process operation, stable product quality and the like.

Detailed Description

The present invention will be further described with reference to the following detailed description.

The controllable atmosphere device of the invention adopts a controllable atmosphere furnace, firstly, the cleaned and dried 20CrMnTi gear part is sent into the controllable atmosphere furnace, the temperature is raised to 850 plus or minus 10 ℃ by exhausting, the temperature is kept for 345min, and the carbon potential in the furnace is controlled to be 1 percent for strong infiltration treatment; then controlling the carbon potential in the furnace to be 0.8 percent, keeping the temperature at 850 +/-10 ℃ for 60min for diffusion treatment; then reducing the furnace temperature to 820 +/-10 ℃, controlling the carbon potential in the furnace to be 0.8%, preserving the temperature for 60min, and then quenching the furnace to 110 +/-10 ℃ by adopting oil in the furnace; and finally tempering and heating to 170 +/-10 ℃, preserving the heat for 160min, and then cooling to room temperature by air. The tested surface hardness of the gear part can reach HRC58-62, and the depth of the penetration layer is 0.8-0.9 mm. The atmosphere controllable device of the invention adopts a controllable atmosphere furnace and can use the gas components of the prior art to form the atmosphere controllable gas.

The controllable atmosphere device of the invention adjusts the flow rate of gas through a flow meter by measuring the carbon potential in the controllable atmosphere furnace, the flow rate of nitrogen is controlled at 80-100ml/min, the flow rate of methanol is controlled at 30-40ml/min, the flow rate of ammonia is controlled at 3-5ml/min, and the flow rate of propane is controlled at 30-40 ml/min.