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Heat treatment method for benefiting impact toughness of screw

A heat treatment method and anti-shock technology, applied in heat treatment furnaces, heat treatment equipment, furnaces, etc., can solve problems such as product cracking, achieve the effects of preventing tempering cracks, high cooling efficiency, and simple process routes

Inactive Publication Date: 2014-12-03
CHENGDU HENGTONG ZHAOYE PRECISION MACHINERY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In view of the possibility of cracking defects in the products obtained by the existing heat treatment process in the above-mentioned prior art, a set of practical and reliable heat treatment process is the key issue to ensure the quality of automobile screws. Heat treatment method for toughness

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] A heat treatment method that is beneficial to the impact toughness of screws is used for heat treatment of automotive screws made of 30# steel, including sequentially performing a quenching step and a tempering step, and the quenching step includes performing sequentially on the automotive screws to be treated The heating process, the heat preservation process and the quenching process, the temperature rise process is to heat the car screw at normal temperature to 810-820 ° C, keep the heat for 8-10 minutes, then heat the salt bath to 760-780 ° C and keep it for 3-4 minutes, and the temperature of the car screw The time of staying between 650°C and the upper temperature limit shall not exceed 20 minutes, and the heating rate during the heating process shall not exceed 2°C / s;

[0022] The cooling process is to use salt water to quench and cool the automobile screws; the tempering step is to heat the automotive screws obtained by quenching to 500-520°C for no less than 4 h...

Embodiment 2

[0027] The present embodiment is further limited on the basis of Embodiment 1: in order to further optimize the quenching quality and improve the cleaning ability of the coolant on the surface of the automobile screw during the quenching process, the brine is chlorine with a concentration of 7-10%. sodium chloride solution.

[0028] In order to further optimize the quenching quality, so that each part of each screw in the batch production of automobile screws can obtain a uniform cooling rate, improve the surface cleaning quality of automobile screws in the quenching process, and stir the process in the quenching step, the stirring The process is carried out synchronously with the cooling process, and the stirring process is to stir at least one of the automobile screw and the brine, so that the relative motion of the automobile screw and the brine occurs in the cooling process.

[0029] In order to eliminate or weaken the influence of the internal stress enriched in the quenc...

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Abstract

The invention discloses a heat treatment method for benefiting impact toughness of a screw, which is used for carrying out heat treatment on a 30# steel automobile screw. The heat treatment method sequentially comprises a quenching process and a tempering process. The quenching process sequentially comprises the following steps: heating, holding and shock cooling. The tempering process comprises the following steps: heating the automobile screw subjected to shock cooling to 500-520 DEG C, holding for at least 4 hours, and cooling with air, wherein the heating rate is not greater than 2 DEG C / second. By using the heat treatment technique, the surface hardness of the existing 35# automobile screw subjected to heat treatment can reach HRC 25-28, and the automobile screw product has the advantages of favorable core toughness, favorable structure and hardness uniformity and no crack.

Description

technical field [0001] The invention relates to the technical field of screw heat treatment, in particular to a heat treatment method that is beneficial to the impact toughness of screws. Background technique [0002] Screws are indispensable connectors in the automobile industry. A standard screw is widely used in automobiles. The material is 35# steel, and the required hardness value is HRC24-29. The most used sizes are M6, M8 and M10. [0003] Since the above screws are used in automobiles, their quality directly affects the safety of passengers. In the production process, their quality requirements are very high, and the quality requirements mainly include the uniformity of tissue hardness and whether there are cracks. The heat treatment process applied to the above screws in the prior art is generally quenched by holding at 820-840°C for not less than 10 minutes, and then tempering at 500-550°C for not less than 4 hours. However, the products obtained by the existing h...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D9/00C21D1/18
Inventor 吴光武
Owner CHENGDU HENGTONG ZHAOYE PRECISION MACHINERY
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