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An operation method for reducing cold-bending cracking at the root of bamboo-jointed steel transverse ribs

A technology of cold bending cracking and operation methods, which is applied in the direction of furnaces, heat treatment equipment, manufacturing tools, etc., can solve problems that affect product quality and cannot be delivered to production, and achieve the effect of improving metal flow and preventing force cracking

Active Publication Date: 2021-03-16
ZHANGJIAGANG HONGCHANG STEEL PLATE CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] In the production process of bamboo steel, cold bending cracks will occur at the junction of the bottom of the transverse rib of bamboo steel and the steel body, which will affect the quality of the product and cannot be delivered for production

Method used

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  • An operation method for reducing cold-bending cracking at the root of bamboo-jointed steel transverse ribs

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] Put the steel billet into the heating furnace with a temperature of 910°C in the heating section and a temperature of 1000°C in the soaking section for heating and keep the temperature in the soaking section for 30 minutes, the temperature rise and fall rate is 8°C / min, and the temperature difference between the head, middle and tail of the billet when it comes out of the furnace is 25°C . The billet temperature is 940°C before rolling, the entrance temperature of finishing rolling is 840°C, and tempering is carried out after finishing rolling, and the highest tempering temperature is 610°C. The pass shape of the rolling rolls in the rolling process is modified, and a circular arc with a radius of 2.5mm is added to the intersection of the root of the transverse rib by changing the right angle of the rolling groove 1 to a rounded angle.

[0019] In April 2019, the steel plant used the above-mentioned improved process to produce 32 batches of bamboo steel SD500, and the n...

Embodiment 2

[0021] Put the billet into the heating furnace with a temperature of 930°C in the heating section and a temperature of 1020°C in the soaking section for heating and keep the temperature constant for 35 minutes in the soaking section, the temperature rise and fall rate is 8°C / min, and the temperature difference between the head, middle and tail of the billet when it comes out of the furnace is 28°C . The billet temperature is 955°C before rolling, the entrance temperature of finishing rolling is 860°C, and tempering is carried out after finishing rolling, and the highest tempering temperature is 620°C. The pass shape of the rolling rolls in the rolling process is modified. By changing the right angle of the rolling groove 1 to a rounded angle, a transitional arc with a radius of 3mm is added to the junction of the root of the transverse rib.

[0022] In April 2019, the steel plant used the above-mentioned improved process to produce 40 batches of bamboo steel SD500, and the num...

Embodiment 3

[0024] Put the billet into the heating furnace with a temperature of 950°C in the heating section and a temperature of 1040°C in the soaking section for heating and keep the temperature in the soaking section for 35 minutes. The temperature rise and fall rate is 10°C / min. . The billet temperature is 970°C before rolling, the entrance temperature of finishing rolling is 880°C, and tempering is carried out after finishing rolling, and the highest tempering temperature is 630°C. The pass shape of the rolling rolls in the rolling process is modified. By changing the right angle of the rolling groove 1 to a rounded angle, a transitional arc with a radius of 4mm is added at the junction of the root of the transverse rib.

[0025] In April 2019, the steel plant used the above-mentioned improved process to produce 37 batches of bamboo steel SD500, and the number of cold-bending cracks in the samples was 0.

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Abstract

The invention provides an operation method for reducing cold bending cracking at transversal rib root parts of bamboo steel. The method mainly comprises the following steps that (1) the uniformity ofthe temperature of a billet heating process is controlled, specifically, soaking of a billet is conducted at 1 / 3 of the total heating time in a heating furnace; (2) the internal structure of the bamboo steel is controlled by setting an inlet temperature of finish rolling, namely the highest self-tempering temperature, wherein the surface of the bamboo steel is provided with tempered martensite, and the core part is provided with pearlite; and (3), the roller caliber is modified, and transition arcs are additionally arranged at joints of the root parts of transversal ribs. According to the operation method, the heating temperature, the soaking temperature, the initial rolling temperature, the finish rolling temperature and the highest self-tempering temperature are controlled during production of the bamboo steel, so that the internal structure of the bamboo steel is changed, and a closed tempered martensite layer with the thickness of 2-3 mm on the surface and a pearlitic structure with thin crystal grains in the core part are obtained; and the transition arcs are additionally arranged at the joints between the transversal rib root parts of the bamboo steel and a steel body to improve the metal flow direction in the rolling process, so that the stress cracking at the root parts caused by aggregating of the metal internal stress is prevented.

Description

technical field [0001] The invention relates to an operation method for reducing cold-bending cracking at the root of a bamboo-jointed steel transverse rib. Background technique [0002] Bamboo steel refers to square steel or round steel with bamboo-like protrusions on the surface. It is used in reinforced concrete and is more firmly combined than ordinary square steel and round steel. The early form of domestic steel bars was bamboo joints. [0003] During the production process of bamboo steel, cold bending cracks will occur at the junction of the bottom of the cross rib of bamboo steel and the steel body, which will affect the quality of the product and cannot be delivered for production. Contents of the invention [0004] In order to solve the above-mentioned problems, the present invention provides an operation method for reducing cold-bending cracking at the root of bamboo steel transverse ribs, the main contents of which are as follows. [0005] An operation metho...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D1/18C21D8/00C21D9/70C21D11/00B21B27/02B21B37/74
CPCB21B27/02B21B37/74C21D1/18C21D8/005C21D9/70C21D11/00C21D2211/008C21D2211/009
Inventor 陆峰刘云祥姚学峰吴彬彬
Owner ZHANGJIAGANG HONGCHANG STEEL PLATE CO LTD