Hot-rolling anneal-free coil rod production method for 8.8 grade high-strength cold forging steel

A production method and high-strength technology, applied in the field of hot rolling of medium carbon cold heading steel wire rods, can solve the problems of large energy consumption, environmental pollution, metal loss, etc., and achieve the effects of improving quality, reducing environmental pollution and saving energy.

Active Publication Date: 2006-07-12
MAANSHAN IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The use of fasteners is different, and the shape of the bolt head is also different. No matter the simple or complex bolt head, in the process of cold heading, the deformation degree of the bolt head is very large, and the material to be cold heading is required to have good Excellent plastic deformation performance; the carbon equivalent commonly used by fastener enterprises is 0.35% ~ 0.55% high-quality carbon steel or alloy steel wire rod, through spheroidizing annealing, the material is softened, and then changed into cold heading process material after pickling and drawing , and then feed into a multi-station cold heading machine for cold heading and rolling to form bolts, and then undergo quenching and tempering heat treatment to make 8.8-grade high-strength bolts; the traditional spheroidizing annealin

Method used

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  • Hot-rolling anneal-free coil rod production method for 8.8 grade high-strength cold forging steel

Examples

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Effect test

Embodiment 1

[0009] Example 1: Carbon cold heading steel with a carbon equivalent of 0.49%, the chemical composition is C-0.37%, Si-0.15%, Mn-0.70%, P-0.016%, S-0.012%; steel mill refining and continuous casting 140 square billet; in the high-speed wire plant, the steel billet is reheated to 1100°C, first rolled at the conventional temperature of the roughing and intermediate rolling mill, and then cooled by controlled water, the rolled piece is finished rolled at 735°C in the finishing rolling unit and reducing sizing mill to Φ8mm Standard wire rod, the accumulative area reduction rate is 81%. After spinning, the coils are unrolled and cooled slowly for 20 minutes, cooled to below 580°C, collected and coiled, cooled naturally and bundled. 5 rolls of 10 tons of wire rod, in a fastener factory, pickled directly without annealing→drawing, and remade into 7.6mm process material, using 13B multi-position cold heading machine made in Taiwan, with 200 pieces / min Upsetting speed, made into M8×20 ...

Embodiment 2

[0010] Example 2: Carbon cold heading steel with a carbon equivalent of 0.44%, the chemical composition is C-0.34%, Si-0.14%, Mn-0.63%, P-0.016%, S-0.01%; steel mill refining and continuous casting 140 square billet; in the high-speed wire plant, the steel billet is reheated to 1100°C, firstly rolled at the conventional temperature of the roughing and intermediate rolling mill, and then cooled by controlled water, and the rolled piece is finished rolled at 770°C in the reducing and sizing mill to form a Φ10mm wire rod. The surface reduction rate is 56%. After silk spinning, the coils are loosened and cooled slowly for 35 minutes, cooled to below 580°C to collect the coils, cooled naturally and bundled. 30 rolls totaling 60 tons. In a fastener factory, direct pickling without annealing→drawing, remade into 9.5mm process material, cold heading into M10×45mm inner hexagonal bolts on general low-speed multi-position cold heading machine , the appearance quality is very good, there...

Embodiment 3

[0011] Example 3: Alloy cold heading steel with carbon equivalent of 0.47%, chemical composition is C-0.23%, Si-0.16%, Mn-1.47%, P-0.016%, S-0.009%, Ti-0.08%, B- 0.003%; refining and continuous casting in the steel mill into 140 billet; in the high-line factory, the billet is reheated to 1100 ° C, first rolled at the conventional temperature of the rough and medium rolling mill, and then cooled by controlled water, the rolled piece is in the reducing and sizing machine at 820 °C ℃ finish rolling into Φ14mm wire rod, the accumulative area reduction rate is 38%. After spinning, the coils are loosely cooled for 20 minutes, cooled to below 580 ℃ and collected into coils, cooled naturally and bundled. 32 volumes totaling 65 tons. In a fastener factory, direct pickling without annealing→drawing, and reworked into 13.5m process material. On general low-speed multi-position cold heading machine, cold heading into M14×60mm inner hexagonal bolts , the appearance quality is very good, th...

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Abstract

The invention provides a method which uses hot-finished non-anneal rod to produce 8.8-grade high-strength cold heading steel. The invention still utilizes general ultra-liner rolling device in the process of rolling medium carbon cold heading steel and utilizes general temperature of 950-1050Deg. C in the rough, middle and pre-finished rolling steps. The finished rolling step utilizes heat engine rolling process which is characterized in that the rolled piece is recovered via water cooling and long channel after the pre-finished rolling, and it is fed into finished-rolling machine when the temperature is reduced to the low-temperature area of 730-830Deg. C, and the steel is transformed at dual-phase (ª†+ª‡) region with large transformation valve; the accumulated draft can reach 35-82%; then the rolled piece is quickly water cooled to 800-620Deg. C to be kept temperature for 600-2400 second and natural cooled to room temperature. The invention can reduce the proportion of pearlite via increasing the proportion of ferrite, to spheroidize a part of pearlite and reduce the strength and rigidity and improve the ductility of material, therefore it can realize the purpose of beating bolt without anneal before cold heading.

Description

technical field [0001] The invention belongs to a steel wire rolling method, in particular to an improved hot rolling method for medium-carbon cold heading steel wire. Background technique [0002] Existing bolt fasteners, especially fasteners below M24, are widely formed by cold heading. The use of fasteners is different, and the shape of the bolt head is also different. No matter the simple or complex bolt head, in the process of cold heading, the deformation degree of the bolt head is very large, and the material to be cold heading is required to have good Excellent plastic deformation performance; the carbon equivalent commonly used by fastener enterprises is 0.35% ~ 0.55% high-quality carbon steel or alloy steel wire rod, through spheroidizing annealing, the material is softened, and then changed into cold heading process material after pickling and drawing , and then feed into a multi-station cold heading machine for cold heading and rolling to form bolts, and then un...

Claims

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Application Information

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IPC IPC(8): B21B1/16B21B45/02
CPCY02P70/10
Inventor 施雄梁胡孝兰孙维华刚许键于同仁宋强
Owner MAANSHAN IRON & STEEL CO LTD
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