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Thermal processing technology for bolts

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

Inactive Publication Date: 2014-03-19
常熟市福熙机械零部件制造有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[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 nuts, and scrap rate sometimes exceeds 10%

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0016] A heat treatment process for bolts, comprising the steps of:

[0017] 1) Preheat the bolts to be processed for 4 hours, and the temperature of the preheating furnace is 360°C;

[0018] 2) Carburizing treatment;

[0019] 3) Then keep warm in a salt bath furnace at 600°C for 5 hours for quenching. The salt solution uses potassium chloride with a concentration of 80g / L, sodium sulfate with a concentration of 200g / L, potassium nitrate with a concentration of 100g / L and a concentration of A mixed solution of 180g / L sodium chloride;

[0020] 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 at a mass ratio of 2:1;

[0021] 5) Quenching in the second stage, using nitrate constant temperature quenching to 100°C, the nitrate quenching agent is a quenching agent mixed with potassium nitrate and sodium nitrate in a mass ratio of 1:2;...

Embodiment 2

[0025] A heat treatment process for bolts, comprising the steps of:

[0026] 1) Preheat the bolts to be treated for 5 hours, and the temperature of the preheating furnace is 370°C;

[0027] 2) Carburizing treatment;

[0028] 3) Then keep warm in a salt bath furnace at 620°C for 6 hours for quenching. The salt solution uses potassium chloride with a concentration of 90g / L, sodium sulfate with a concentration of 210g / L, potassium nitrate with a concentration of 110g / L and a concentration of A mixed solution of 190g / L sodium chloride;

[0029] 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 at a mass ratio of 2:1;

[0030] 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; ...

Embodiment 3

[0034] A heat treatment process for bolts, comprising the steps of:

[0035] 1) Preheat the bolts to be processed for 4.5 hours, and the temperature of the preheating furnace is 365°C;

[0036] 2) Carburizing treatment;

[0037] 3) Then keep warm in a salt bath furnace at 610°C for 5.5 hours for quenching. The salt solution uses potassium chloride with a concentration of 85g / L, sodium sulfate with a concentration of 204g / L, potassium nitrate with a concentration of 107g / L and a concentration of A mixed solution of 183g / L sodium chloride;

[0038] 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 at a mass ratio of 2:1;

[0039] 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 ratio of ...

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Abstract

A disclosed thermal processing technology for bolts comprises the following steps: 1) pre-heating to-be-processed bolts for 4-5 h, pre-heating a furnace to a temperature of 360-370 DEG C; 2) performing carburization processing; 3) keeping the bolts in a salt bath furnace with a temperature of 600-620 DEG C for 5-6 h and quenching; 4) performing first-stage quenching, employing a nitrate quenching agent and quenching to 500-510 DEG C with a constant velocity of 50-55 DEG C / min, wherein the nitrate quenching agent is a quenching agent prepared by mixing potassium nitrate and sodium nitrate with a mass ratio of 2:1; 5) performing second-state quenching, employing a nitrate quenching agent and quenching to 100-110 DEG C, wherein the nitrate quenching agent is a quenching agent prepared by mixing potassium nitrate and sodium nitrate with a mass ratio of 1:2; 6) performing third-stage quenching, employing hot water with a temperature of 200-205 DEG C and quenching to 230-235 DEG C; and 7) keeping the bolts in a tempering furnace with a temperature of 300-305 DEG C for 8-10 h, and cooling in air to room temperature. By employing the thermal processing technology for the bolts, the prepared bolts are small in cross-section shrinkage, improved in match rate and reduced in rejection rate, and cyanide penetrating agents harmful to human body and environment are 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 bol...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D9/00C21D1/18C21D1/607C21D1/46
Inventor 查希炜查清源
Owner 常熟市福熙机械零部件制造有限公司
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