Tempering heat treatment method of mn series high-strength finish-rolled threaded steel bar

A heat treatment method and technology for finishing threads, applied in heat treatment furnaces, heat treatment equipment, furnaces, etc., can solve the problems of large tissue stress, high sensitivity to hydrogen embrittlement, and easy occurrence of brittle fracture, so as to achieve low production costs and reduce tissue stress. , to ensure the effect of strong toughness

Active Publication Date: 2015-10-21
HEBEI IRON AND STEEL
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, because the Mn-based high-strength finish-rolled threaded steel bar is air-cooled after rolling to obtain bainite and martensite structures, the structure stress is large and the susceptibility to hydrogen embrittlement is high, and brittle fracture is very easy to occur

Method used

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  • Tempering heat treatment method of mn series high-strength finish-rolled threaded steel bar

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] Embodiment 1: The tempering heat treatment method of the Mn-based high-strength finish-rolled threaded steel bar adopts the following specific process.

[0016] Put the steel into the heating furnace and heat it. After 3.5 hours of heating, the furnace temperature rises to 280°C; keep it in the heating furnace at 280°C for 6.0 hours; stop heating, and let the steel cool in the heating furnace until it cools down to At room temperature, the Mn-based high-strength finish-rolled rebar is obtained. The obtained high-strength finish-rolled threaded steel bar: tensile strength Rm=1214MPa, yield strength Rel=954MPa, elongation after fracture A=15%, total elongation under maximum force Agt=5.20%, meeting the PSB930 standard.

Embodiment 2

[0017] Embodiment 2: The tempering heat treatment method adopts the following specific processes.

[0018] Put the steel into the heating furnace for heating. After 4.0 hours of heating, the furnace temperature rises to 350°C; keep it in the heating furnace at 350°C for 6.0 hours; stop heating, and let the steel cool in the heating furnace until it cools down to At room temperature, Rm=1193MP, Rel=923MPa, A=15%, Agt=5.50%, Mn series high-strength finish-rolled rebar that meets PSB830 grade.

Embodiment 3

[0019] Embodiment 3: The tempering heat treatment method adopts the following specific processes.

[0020] Put the steel into the heating furnace for heating. After 3.0 hours of heating, the furnace temperature rises to 200°C; keep it in the heating furnace at 200°C for 5.0 hours; stop heating, and let the steel cool in the heating furnace until it cools down to At room temperature, Rm=1466MP, Rel=1125MPa, A=13%, Agt=4.50%, Mn series high-strength finish-rolled rebar that meets PSB1080 grade.

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Abstract

The invention discloses a tempering heat treatment method of Mn-series high-strength finish rolling thread reinforcing steel bars. The method comprises a temperature rising process, a heat preservation process and a cooling process. According to the heat preservation process, the heat preservation temperature ranges from 200 DEG C to 600 DEG C, and the heat preservation time ranges from three hours to six hours. According to the method, a heat treatment heating furnace is utilized for performing heating, a martensitic structure obtained after rolled air cooling is decomposed, supersaturated carbon in martensite is precipitated, a reversed crystal lattice is basically restored to be normal, and therefore structural stress is eliminated, and a steel material structure is converted into bainite and a corresponding tempering structure; along with disappearance of the martensite, the strength of steel is reduced, the heat preservation time is increased, the steel hydrogen content is reduced, the hydrogen embrittlement sensitivity of the steel is greatly reduced, obdurability of the high-strength finish rolling thread reinforcing steel bars is ensured, and the structural stress and the hydrogen embrittlement sensitivity are reduced. According to the method, the obdurability of the high-strength finish rolling thread reinforcing steel bars is ensured, the structural stress and the hydrogen embrittlement sensitivity are reduced, meanwhile, the production technology is simplified, the equipment requirement is reduced, and the method has the advantages of being simple in process and low in production cost.

Description

technical field [0001] The invention relates to a heat treatment method for steel, in particular to a tempering heat treatment method for Mn-based high-strength finish-rolled threaded steel bars. Background technique [0002] High-strength finish-rolled rebar is widely used in large-scale projects such as high-speed railways, bridges and super high-rise buildings, and is an indispensable steel for modern construction. At present, the production steel type of PSB830, PSB930, PSB1080 high-strength and high-quality finish-rolled rebar is generally 40Si2MnV, which adopts the production process of on-line quenching and tempering. The production process of the above-mentioned steel types is complex and requires high production line equipment. Another high-strength and high-quality finish-rolled threaded steel bar is a Mn-based high-strength finished-rolled threaded steel bar produced with cheap Mn, Cr, and Si as the main alloying elements. This technology has no special requireme...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D6/00C21D9/00C22C38/38
Inventor 王全利白瑞国王井伟关丛英马海峰王晓东
Owner HEBEI IRON AND STEEL
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