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Heat treatment process of bolt processing

A process and bolt technology, applied in the field of hardware, can solve the problems of scrap rate exceeding 10%, large section shrinkage rate, low nut fitting rate, etc., and achieve the effect of reducing scrap rate, section shrinkage rate and improving strength.

Inactive Publication Date: 2013-03-27
NINGBO TENGLING IND & TRADE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

For high-strength nuts that require high strength, the current heat treatment process is to use carburizing or cyanide + quenching and tempering processes, and a complete annealing process of 850-900 ° C for 10 hours, but the bolts produced by this process are quenched When the section shrinkage rate is large, the deformation rate is large, the matching rate with the nut is low, and the scrap rate sometimes exceeds 10%

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] A heat treatment process for bolt processing, the steps of which are:

[0024] Preheat the fasteners to be treated in a preheating furnace at 250-280°C for 1.5 hours and then put them into the carburizing furnace for carburizing treatment;

[0025] Quenching at 750±20°C for 2.5 hours in a sodium chloride solution neutral salt bath furnace with a weight percentage of 8%-10%;

[0026] Quenching is carried out in two stages, the first stage is quenching with nitrate at a constant speed of 30-35°C / min to 420-450°C, and the second stage is quenching with nitrate salt at 250±20°C to 250-280°C at a constant temperature Tempering treatment; the nitrate quenching agent is a quenching agent mixed with potassium nitrate and sodium nitrate in a ratio of 1:1 by weight;

[0027] Tempering treatment is to keep warm in a tempering furnace at 420-450°C for 3.5 hours and then air-cool to normal temperature.

Embodiment 2

[0029] A heat treatment process for bolt processing, the steps of which are:

[0030] Preheat the fasteners to be treated in a preheating furnace at 250-280°C for 2 hours and then put them into the carburizing furnace for carburizing treatment;

[0031] Quenching at 750±20°C for 3 hours in a sodium chloride solution neutral salt bath furnace with a weight percentage of 8%-10%;

[0032] Quenching is carried out in two stages, the first stage is quenching with nitrate at a constant speed of 30-35°C / min to 420-450°C, and the second stage is quenching with nitrate salt at 250±20°C to 250-280°C at a constant temperature Tempering treatment; the nitrate quenching agent is a quenching agent mixed with potassium nitrate and sodium nitrate in a ratio of 1:1 by weight;

[0033] Tempering treatment is to keep warm in a tempering furnace at 420-450°C for 3 hours and then air-cool to normal temperature.

Embodiment 3

[0035] A heat treatment process for bolt processing, the steps of which are:

[0036] Preheat the fasteners to be treated in a preheating furnace at 250-280°C for 1 hour and then put them into the carburizing furnace for carburizing treatment;

[0037] Quenching at 750±20°C for 3 hours in a sodium chloride solution neutral salt bath furnace with a weight percentage of 8%-10%;

[0038] Quenching is carried out in two stages, the first stage is quenching with nitrate at a constant speed of 30-35°C / min to 420-450°C, and the second stage is quenching with nitrate salt at 250±20°C to 250-280°C at a constant temperature Tempering treatment; the nitrate quenching agent is a quenching agent mixed with potassium nitrate and sodium nitrate in a ratio of 1:1 by weight;

[0039] Tempering treatment is to keep warm in a tempering furnace at 420-450°C for 3 hours and then air-cool to normal temperature.

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PUM

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Abstract

The invention relates to a heat treatment process of bolt processing. The process comprises the following steps: preheating a fastener to be treated, and putting the preheated fastener into a carburizing furnace for carburizing; and thermal insulating in a neutral salt bath furnace, and quenching, wherein the quenching is carried out in two stages, in the first stage, uniform-speed quenching is carried out; and in the second stage, constant-temperature quenching is conducted for tempering treatment; and the tempering treatment is thermal insulation in a tempering furnace and then air cooling to normal temperature. By adopting the above technical scheme, the metallurgical structure is uniform and relatively round and smooth, and crystal grains are small, which is more beneficial to increasing the intensity in cases of plastic deformation, the reduction of cross section is small, and the scrap rate is low.

Description

technical field [0001] The invention belongs to the field of hardware, in particular to a heat treatment process for bolt processing. Background technique [0002] The bolt production method in the prior art includes production processes such as plate element, annealing, pickling, wire drawing, forming, tapping, heat treatment, and surface treatment. For high-strength nuts that require high strength, the current heat treatment process is to use carburizing or cyanide + quenching and tempering processes, and a complete annealing process of 850-900 ° C for 10 hours, but the bolts produced by this process are quenched When the shrinkage rate of the section is large, the deformation rate is large, the matching rate with the nut is low, 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 bolt processing. The bolts produced by the technical scheme have a small shrinkage rate,...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23F17/00C21D1/18C21D1/607C21D9/00
Inventor 任旭辉
Owner NINGBO TENGLING IND & TRADE
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