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Method for carbonitriding heat treatment of screws

A heat treatment method, carbonitriding technology, applied in the direction of coating, metal material coating process, solid-state diffusion coating, etc., can solve the problems such as the hardness of the shallow surface of the infiltration layer, and achieve high toughness, wear resistance and fatigue strength The effect of improving and reducing the risk of hydrogen embrittlement in electroplating

Active Publication Date: 2015-12-30
佳兴紧固件工业(苏州)有限公司
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  • Summary
  • Abstract
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  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Heat treatment is a common process to improve the mechanical properties of screws, but the current carbonitriding process used in screw processing has the disadvantages of high hardness of the nitriding layer but shallow carburizing layer or a large hardening depth of the carburizing layer but low surface hardness.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] Clean the screws to be heat-treated with warm water and high-pressure spraying to remove the residual oil and diesel oil during the thread rubbing process, reduce the pollution to the equipment, ensure even carburization of the parts, and control the water pressure to 1kgf / cm during the cleaning process 2 .

[0023] Adjust the speed of the feeder to 30Hz / rpm, the feeder will transport the screws to the continuous furnace for continuous preheating carbonitriding treatment, adjust the main speed of the continuous furnace for continuous preheating, the preheating treatment is two-stage Preheating, the first preheating temperature is 600°C, and the holding time is 10 minutes to reduce the internal stress generated by the screw when it is headed and rubbed, reduce the internal and external temperature difference of the screw, and eliminate the cracking and cracking of the screw due to work hardening. Deformation, the preheating temperature of the second stage is 860°C, and t...

Embodiment 2

[0027] Clean the screws to be heat-treated by spraying with warm water and high pressure to remove the residual engine oil and diesel oil during the screw rubbing process, reduce the pollution to the equipment, and ensure even carburization of the parts. During the cleaning process, the water pressure is controlled at 1.2kgf / cm 2 .

[0028] Adjust the speed of the feeder to 45Hz / rpm, the feeder will transport the screws to the continuous furnace for continuous preheating carbonitriding treatment, adjust the main speed of the continuous furnace for continuous preheating, the preheating treatment is two-stage Preheating, the first preheating temperature is 600°C, and the holding time is 13 minutes to reduce the internal stress generated by the screw when it is headed and rubbed, reduce the internal and external temperature difference of the screw, and eliminate the cracking and cracking of the screw due to work hardening. Deformation, the second preheating temperature is 870°C, ...

Embodiment 3

[0032] Clean the screws to be heat-treated with warm water and high-pressure spray to remove the residual oil and diesel oil from the screw rubbing process, reduce the pollution to the equipment, and ensure even carburization of the parts. During the cleaning process, the water pressure is controlled at 1.5kgf / cm 2 .

[0033] Adjust the speed of the feeding machine to 60Hz / rpm, the feeding machine will transport the screws to the continuous furnace for continuous preheating carbonitriding treatment, adjust the main speed of the continuous furnace for continuous preheating, and the preheating treatment is two-stage Preheating, the first preheating temperature is 600°C, and the holding time is 15 minutes to reduce the internal stress generated by the screw when it is headed and rubbed, reduce the internal and external temperature difference of the screw, and eliminate the cracking and cracking of the screw due to work hardening. Deformation, the second preheating temperature is ...

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Abstract

The invention discloses a method for carbonitriding heat treatment of screws. The method comprises the following steps of: (1) cleaning the screws needing heat treatment; (2) adjusting the speed of a feeding machine; (3) adjusting the main speed of a continuous furnace to carry out continuous preheating, and carrying out carbonitriding heat treatment on the preheated screws, wherein the preheating temperature is controlled at 860-890DEG C, the carbon potential is 1%-1.2%, and the ammonia gas flow is 0.2-0.5nm<3> / h; (4) carrying out primary quenching; (5) carrying out secondary quenching by adopting quick brightening oil; (6) cleaning the surfaces of the screws; and (7) tempering at 370-420 DEG C for 70-90min. The surface hardness of the screws processed by adopting the method is larger than 450HV0.3, the core hardness is 280-350HV0.3, the toughness is high, the electroplating hydrogen embrittlement risk is low, and the wear resistance and fatigue strength are improved.

Description

technical field [0001] The invention relates to the field of screw processing, in particular to a heat treatment method for carbonitriding of screws. Background technique [0002] Screws are commonly used parts in equipment. With the development of modern industrial level, higher requirements are put forward for screw hardness, wear resistance, corrosion resistance, bending strength and contact fatigue strength. Heat treatment is a common process to improve the mechanical properties of screws, but the current carbonitriding process used in screw processing has the disadvantages of high hardness of the nitriding layer but shallow carburizing layer or a large hardening depth of the carburizing layer but low surface hardness. Contents of the invention [0003] In order to solve the above technical problems, the object of the present invention is to provide a heat treatment method for carbonitriding of screws. In order to realize the foregoing invention object, the technical ...

Claims

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Application Information

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IPC IPC(8): C21D1/18C23C8/32
Inventor 庄英树
Owner 佳兴紧固件工业(苏州)有限公司
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