Continuous induction heat treatment process for high-strength finish-rolled spiral steel bar

A technology of induction heat treatment and finish rolling of threads, applied in heat treatment furnaces, heat treatment equipment, improvement of process efficiency, etc., can solve the problems of coarse grains in the center, unstable performance of steel bars, shallow hardening layer, etc., and achieve fine grains. The effect of good matching of strength and toughness, and high strength level

Inactive Publication Date: 2006-01-04
ANGANG STEEL CO LTD
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Problems solved by technology

However, because the temperature of the steel bar itself before water penetration fluctuates greatly due to the influence of various factors such as the rolling line's operating season, climate, and water temperature, the performance of the steel bar after heat treatment is unstable, the hardened layer is very shallow, and the grains in the center are coarse and cannot be fully processed. To give full play to the potential of the finish-rolled threaded steel bar itself, breakage and other phenomena sometimes occur in practical applications

Method used

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Embodiment Construction

[0011] According to the continuous heat treatment process provided by the present invention, the chemical composition by weight percentage is: C: 0.40-0.60%, Si: 0.60-2.0%, Mn: 0.60-2.0%, Mo: 0.10-0.40%, V: 0.10-0.30 %, P, S≤0.03% of the finished rolled threaded steel bar is automatically uploaded to the conveying roller table from the feeding system of the continuous heat treatment device, and the steel bar is heated by an induction heater at a speed of 2-6 m / min in a rotating state. Heating the steel bars to 820-980°C, and then enter the cooler for quenching treatment, after quenching, the temperature is lower than 300°C, and then enter the next induction heater for tempering heat treatment, the tempering temperature is 580-680°C, after the above continuous After the heat treatment process, the finished rolled threaded steel bar with a strength level of 800MPa is obtained. Finally, it is automatically sent to the unloading system and enters the finished product collection ta...

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Abstract

The present invention is heat treatment process of high-strength finish-rolled spiral steel bar. The finish-rolled spiral steel bar in rotary state is fed from the feeding system of the continuous heat treatment apparatus to the roller conveyer at the speed of 2-6 m / min, heated to 800-1000 deg.c in one induction heater, quenched in the cooler at temperature lower than 300 deg.c, and tempered in one other induction heater at 500-700 deg.c to produce finish-rolled spiral steel bar of higher strength grade. The finish-rolled spiral steel bar through said heat treatment process has obviously raised mechanical performance, thick hardened layer, fined crystal grains, stable performance, high strength and high toughness.

Description

technical field [0001] The invention belongs to the heat treatment process of finish-rolled threaded steel bars. Background technique [0002] The high-strength finish-rolled threaded steel bar is a steel bar with a special shape of external thread rolled on the whole steel bar by hot rolling method, and then heat-treated to improve the mechanical properties. Before the present invention was made, the production of conventional finish-rolled threaded steel bars was heat-treated in the rolling process by using the waste heat of the steel bars after hot-rolling. Bed cooling→cutting to length→flat head→quality inspection and packaging→storage. Under normal circumstances, the rolling temperature is 1100-1150°C, the temperature before water penetration is 950-1000°C, and the cooling time is 1.5 seconds. After water penetration, the surface temperature of the finished rolled threaded steel bar is below 400°C, and the temperature of the finished rolled threaded steel bar on the co...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D9/60
CPCY02P10/25
Inventor 金文旭姜雨王长顺马普生高丽娟张福祥
Owner ANGANG STEEL CO LTD
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