Post-rolling control cooling process for hot-rolled H-shape steel

A technology for controlled cooling and H-beams, applied in the field of steel rolling, can solve the problems of reduced steel service performance, low cooling rate, decreased welding performance, etc., to achieve the effect of improving strength and toughness, and ensuring uniformity

Active Publication Date: 2010-06-30
MAANSHAN IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the technology is still immature, and there are problems such as uneven cooling and deformation of the rolled piece.
And in our country, users are not easy to accept steel products strengthened by quenching after rolling and self-tempering process. They think that the tempered layer formed after quenching and self-tempering will reduce the performance of steel products. The main problems are: the yield strength ratio of steel products is large; welding performance Decrease; the stress aging of steel is large
Therefore, this technology cannot be popularized and applied in our country.
[0004] "Steel Rolling" magazine, 2004, No. 5, pages 15-17, published a paper titled "Research on Controlled Cooling Process of Hot-rolled H-shaped Steel", wh

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] Example 1: Rolling 345MPa strength grade hot-rolled H-shaped steel with the composition of Q275 strength grade steel

[0030] Common carbon structural steel continuous casting shaped blanks with chemical composition of 0.10-0.17%C, 0.17-0.35%Si, 0.75-1.00%Mn, 0.035%S, 0.035%P are used as raw materials, and the specification of continuous casting blanks is 750mm×450mm ×120mm, the finished product size is 594mm×302mm×14mm×23mm, in the production process of "walking beam heating furnace heating → high pressure water descaling → billet rolling → universal rough rolling unit reciprocating rolling → universal finishing mill rolling" Rolling on the process, including one blanking machine, two universal roughing mills and an edger placed between the two universal roughing mills to form a universal roughing mill, a universal finishing mill, and a billet rolling track About 7 times, 9-10 universal passes, 3-5 edging passes, 1 universal finish rolling pass, billet heating temperat...

Embodiment 2

[0034] Example 2: Rolling 450MPa strength grade hot-rolled H-shaped steel with the composition of Q345 strength grade steel

[0035] The common low-alloy structural steel continuous casting special-shaped blank with chemical composition of 0.14-0.17%C, 0.35-0.50%Si, 1.20-1.40%Mn, 0.035%S, 0.035%P, 0.02-0.04%V is used as raw material, continuous casting The billet size is 750mm×450mm×120mm, and the finished product size is 338mm×325.4mm×30.5mm×30.5mm. Heating in the “walking beam heating furnace → high pressure water descaling → billet rolling → reciprocating rolling in the universal roughing mill → Rolling on the production process of "universal finishing mill rolling", in which one blanking machine, two universal roughing mills and an edger placed between the two universal roughing mills form the universal roughing mill, and one Universal finish rolling mill, billet rolling passes about 6 times, universal pass 7-8 passes, edge rolling pass 2-4 passes, universal finish rolling...

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Abstract

The invention provides a post-rolling control cooling process for hot-rolled H-shape steel. The hot-rolled H-shape steel enters a cooling device after the rolling is finished, an upper nozzle and a lower nozzle are respectively aligned with upper/lower R parts of the hot-rolled H-shape steel to carry out water spray cooling, and a left nozzle and a right nozzle are respectively aligned with left/right flank centers of the hot-rolled H-shape steel to carry out water spray cooling. The invention is characterized in that the pressure of cooling water is within 0.7 to 1.2MPa, the water quantity is within 1,200 to 2,000m3/hour, the cooling rate is within 75 to 150 DEG C/s and the cooling time is within 3 to 5 seconds; and the hot-rolled H-shape steel is cooled to 20 to 30 DEG C above the martensitic phase transformation point of the corresponding steel grade after the rolling under the temperature of 850 to 1,000 DEG C is finished. By adopting the cooling process in the invention, the actual grain size of ferrite at the core part of the hot-rolled H-shape steel can be refined from 8-10 grades to 10-12 grades, and a tissue of bainite plus sorbite can be formed on the surface of the hot-rolled H-shape steel, thereby obviously improving the strength and toughness of the hot-rolled H-shape steel and improving the yield strength of the hot-rolled H-shape steel by more than 70MPa.

Description

technical field [0001] The invention belongs to the technical field of steel rolling, and in particular relates to a post-rolling controlled cooling process for hot-rolled H-shaped steel. Background technique [0002] At present, the H-beam hot rolling production line has not yet formed a mature cooling theory and cooling process technology, which has become the bottleneck of industrial production. This is mainly due to the complexity of the cross-sectional shape of the H-beam, and its on-line cooling is prone to residual water at the waist and uneven cooling, which will affect the cross-sectional shape and performance uniformity of the rolled piece, and the product is prone to internal and external expansion and deformation. Web waves, cracks and other defects. [0003] In recent years, this technology has attracted the attention of domestic and foreign enterprises and scientific research institutes, and research reports have been reported in some countries such as Japan, ...

Claims

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Application Information

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IPC IPC(8): B21B45/02B21B37/76
Inventor 苏世怀赵宪明程鼎孙维耿承浩吴迪吴结才奚铁汪开忠
Owner MAANSHAN IRON & STEEL CO LTD
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