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Heat treatment method for automobile SCM435 steel high-strength fastener

A heat treatment method and fastener technology, applied in the field of heat treatment, can solve the problems of surface carburization of fasteners, surface cracks of fasteners, etc., and achieve the effects of increasing productivity, preventing cracks, and shortening process time.

Inactive Publication Date: 2017-12-22
厦门真冈热处理有限公司
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Problems solved by technology

However, in the actual production of SCM435 steel fasteners, after heat treatment, there will be metallographic structure ferrite or bainite, and carburization will appear on the surface of the fasteners, resulting in cracks on the surface of the fasteners.

Method used

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  • Heat treatment method for automobile SCM435 steel high-strength fastener
  • Heat treatment method for automobile SCM435 steel high-strength fastener

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Embodiment Construction

[0028] The heat treatment method of automobile SCM435 steel high-strength fasteners, including steps:

[0029] (1) Heating stage

[0030] Send the fasteners into the heating furnace and enter into Zone I-IV in sequence. The heating temperature from Zone I to Zone IV is controlled at 870°C±5°C, methanol is introduced at a rate of 20-40ml / min, and propane is introduced. , control the carbon potential to 0.40% ± 0.04%, and the heating time of the fastener in the heating furnace is 50-80 minutes.

[0031] The heating furnace is preferably a continuous controllable atmosphere mesh belt furnace. The feed rate of methanol is preferably 28ml / min. The heating time of the fastener in the heating furnace is preferably 70 minutes.

[0032] (2) Quenching stage

[0033] The heated fasteners enter the oil tank for quenching. When quenching and cooling, the oil temperature is 60-70°C, and the quenching oil is circulated and stirred. After quenching, the metallographic structure of the fa...

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Abstract

The invention discloses a heat treatment method for high-strength fasteners made of SCM435 steel for automobiles, comprising steps: (1) In the heating stage, the fasteners are sent into a heating furnace, the heating temperature is controlled at 870°C ± 5°C, and methanol is passed through , the feed rate is 20-40ml / min, feed propane, control the carbon potential to be 0.40%±0.04%, and the heating time is 50-80 minutes; (2) quenching stage, the heated fastener enters the oil tank for quenching, When quenching and cooling, the oil temperature is 60-70°C, and the quenching oil is stirred in circulation; (3) Tempering stage, after quenching, the fastener enters the tempering furnace, and the tempering time is 130-170min; when the hardness requirement is 33-38HRC, tempering The temperature is 500-530°C; when the hardness requirement is 38-42HRC, the tempering temperature is 430-460°C. Passing methanol and controlling the carbon potential at 0.40±0.04% can better balance the carbon concentration inside and on the surface of the workpiece to avoid carburization and ensure that no cracks appear on the surface of the workpiece.

Description

technical field [0001] The invention relates to a heat treatment method, in particular to a heat treatment method for automobile SCM435 steel high-strength fasteners. Background technique [0002] The rapid development of the automobile industry has driven the development of domestic automobile fasteners. However, the fastener industry cannot meet the production needs of the automobile industry. The strength of raw materials cannot meet the production needs of high-strength fasteners, and the technology of heat treatment companies cannot meet The production demand of high-strength fasteners, therefore, the market of low-light fasteners is saturated, and high-strength special-shaped fasteners have long been imported. [0003] In order to meet the production needs of high-strength fasteners, the selection of high-quality materials and the use of advanced heat treatment processes are the key to ensuring the inherent quality of fasteners. [0004] The commonly used steel for hi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/18C21D9/00C21D1/74
CPCC21D1/18C21D1/74C21D9/0093
Inventor 胡大维张雪梅胡敬华
Owner 厦门真冈热处理有限公司
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