Heat treatment process for bolts

A bolt and process technology, which is applied in the field of heat treatment of bolts, can solve the problems of large bolt section shrinkage rate, large deformation rate, and low nut fit ratio, and achieve the effects of small section shrinkage rate, reduced scrap rate, and improved fit rate.

Inactive Publication Date: 2017-05-31
QINGDAO XIUPOER TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] The treatment process for high-strength bolts is to use carburizing or cyanide plus quenching and tempering processes, and a complete annealing process with a temperature of 850-900 ° C for 10 hours, but the bolts produced by this process have a reduction in area during quenching. Larger, large deformation rate, low matching rate with nuts, scrap rate sometimes exceeds 10%

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0014] The technical scheme of the concrete implementation of the present invention is: the heat treatment process of a kind of bolt of embodiment 1, comprises the steps:

[0015] 1) Preheat the bolts to be treated for 4 hours, and the temperature of the preheating furnace is 360°C;

[0016] 2) Carburizing treatment;

[0017] 3) Insulate in the salt-bath furnace of 600 ℃ for 5 hours to quench again, the salt liquid adopts the potassium chloride that concentration is 80g / L, the sodium sulfate that concentration is 200g / L, the potassium nitrate that concentration is 100g / L and concentration is A mixed solution of 180g / L sodium chloride;

[0018] 4) Quenching in the first stage, using nitrate to quench at a constant speed of 50°C / min to 500°C, the nitrate quenching agent is a quenching agent mixed with potassium nitrate and sodium nitrate in a mass ratio of 2:1;

[0019] 5) Quenching in the second stage, using nitrate constant temperature quenching to 100°C, the nitrate quenchi...

Embodiment 2

[0023] A heat treatment process for bolts, comprising the steps of:

[0024] 1) Preheat the bolts to be treated for 5 hours, and the temperature of the preheating furnace is 370°C;

[0025] 2) Carburizing treatment;

[0026] 3) insulated in a salt bath furnace at 620°C for 6 hours to quench, the salt solution adopts a concentration of potassium chloride of 90g / L, a concentration of sodium sulfate of 210g / L, a concentration of potassium nitrate of 110g / L and a concentration of A mixed solution of 190g / L sodium chloride;

[0027] 4) Quenching in the first stage, using nitrate to quench at a constant speed of 55°C / min to 510°C, the nitrate quenching agent is a quenching agent mixed with potassium nitrate and sodium nitrate in a mass ratio of 2:1;

[0028] 5) Quenching in the second stage, using nitrate constant temperature quenching to 110°C, the nitrate quenching agent is a quenching agent mixed with potassium nitrate and sodium nitrate in a mass ratio of 1:2;

[0029] 6) Que...

Embodiment 3

[0032] A heat treatment process for bolts, comprising the steps of:

[0033] 1) Preheat the bolts to be treated for 4.5 hours, and the temperature of the preheating furnace is 365°C;

[0034] 2) Carburizing treatment;

[0035] 3) insulated in the salt-bath furnace of 610 ℃ for 5.5 hours to quench again, the potassium chloride that the concentration is 85g / L, the sodium sulfate that the concentration is 204g / L, the potassium nitrate that the concentration is 107g / L and the concentration of salt solution are A mixed solution of 183g / L sodium chloride;

[0036] 4) Quenching in the first stage, using nitrate to quench at a constant speed of 52°C / min to 504°C, the nitrate quenching agent is a quenching agent mixed with potassium nitrate and sodium nitrate in a mass ratio of 2:1;

[0037] 5) Quenching in the second stage, using nitrate constant temperature quenching to 105°C, the nitrate quenching agent is a quenching agent mixed with potassium nitrate and sodium nitrate in a mass...

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PUM

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Abstract

The invention discloses a heat treatment process for bolts. The heat treatment process comprises the following steps that (1) the to-be-treated bolts are preheated for 4-5 hours, and the temperature of a preheating furnace is 360-370 DEG C; (2) carburizing treatment is conducted; (3) the bolts are subjected to heat preservation for 5-6 hours in a salt-bath furnace at the temperature of 600-620 DEG C and then subjected to quenching; (4) the first stage of quenching is conducted, specifically, the bolts are quenched to 500-510 DEG C at the constant speed of 50-55 DEG C / min through a nitrate quenching agent which is prepared by mixing potassium nitrate and sodium nitrate at the mass ratio of 2:1; (5) the second stage of quenching is conducted, specifically, the bolts are quenched to 100-110 DEG C at a constant temperature through a nitrate quenching agent which is prepared by mixing potassium nitrate and sodium nitrate at the mass ratio of 2:1; (6) the third stage of quenching is conducted, specifically, the bolts are quenched to 230-235 DEG C through hot water with the temperature of 200-205 DEG C; and (7) the bolts are subjected to heat preservation for 8-10 hours in a tempering furnace at 300-305 DEG C and then subjected to air cooling to the normal temperature. According to the heat treatment process for the bolts, the reduction of area of the bolts prepared through the heat treatment process is low, the match rate is increased, the rejection rate is decreased, and using of cyanide osmotic agents harmful to human bodies and environment is avoided.

Description

technical field [0001] The invention relates to a heat treatment process for bolts. Background technique [0002] The treatment process of high-strength bolts is to use carburizing or cyanide plus quenching and tempering, and a complete annealing process of 850-900 ° C for 10 hours, but the bolts produced by this process have a reduction in area during quenching. Larger, large deformation rate, low matching rate with the nut, and the scrap rate sometimes exceeds 10%. Contents of the invention [0003] The object of the present invention is to provide a heat treatment process for bolts, the bolts produced by it have a small shrinkage of area, increase the matching rate, reduce the scrap rate, and avoid the use of cyanide penetrating agents harmful to human body and environment. [0004] In order to achieve the above object, the technical solution of the present invention is to design a heat treatment process for bolts, comprising the steps of: [0005] 1) Preheat the bolt...

Claims

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Application Information

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IPC IPC(8): C21D1/19C21D1/60C23C8/22
CPCY02P10/20
Inventor 王爱红
Owner QINGDAO XIUPOER TECH CO LTD
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