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High-homogeneous large-size ultrahigh-strength steel bar and production method thereof

A technology of ultra-high strength and production method, applied in the field of ultra-high strength steel, to achieve the effect of reducing segregation

Active Publication Date: 2015-04-29
宝武特种冶金有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0025] The above prior art can only produce steel bars less than 400mm

Method used

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  • High-homogeneous large-size ultrahigh-strength steel bar and production method thereof
  • High-homogeneous large-size ultrahigh-strength steel bar and production method thereof
  • High-homogeneous large-size ultrahigh-strength steel bar and production method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0050] (1) VIM smelting is fully stirred, ∮720mm electrode (steel ingot) is poured at 1530°C, the electrode is kept at 650°C±10°C for 20 hours, furnace cooled to 500°C, air-cooled and annealed, then polished. The electrode is remelted in a vacuum consumable furnace to ∮810mm×2650mm steel ingot, and the steel ingot is annealed at 650℃~670℃ for 30 hours and then polished to ∮800mm×2650mm (height-to-diameter ratio 3.3).

[0051] (2) forging

[0052] Steel ingot heating: Furnace loading temperature: 650°C; steel ingot heating rate: 100°C / hour, the temperature rises to 800°C for 3 hours, and the steel ingot continues to heat up, heating rate: 90°C / hour, when the temperature reaches 1220°C, the steel ingot is out of the furnace Forging ∮ 350mm*450mm pliers, the ingot is kept in the heating furnace for 2 hours, turned over 90 degrees, and the ingot is returned to the furnace for 2 hours for forging.

[0053] One-time upsetting and drawing: place the steel ingot with pliers on a circ...

Embodiment 2

[0058] (1) VIM smelting is fully stirred, ∮720mm electrode (steel ingot) is poured at 1550°C, the electrode is kept at 650°C±10°C for 20 hours, furnace cooled to 500°C, air-cooled and annealed, then polished. The electrodes are remelted in a vacuum consumable furnace with a ∮810mm×2650mm (height-to-diameter ratio 3.3) steel ingot, and the steel ingot is annealed at 650°C to 670°C for 30 hours and then polished.

[0059] (2) forging

[0060] Steel ingot heating: Furnace loading temperature: 650°C; steel ingot heating rate: 90°C / hour, the temperature rises to 800°C for 3.5 hours and then the steel ingot continues to heat up, heating rate: 90°C / hour, when the temperature reaches 1230°C, the steel ingot is out of the furnace Forging ∮ 350mm*450mm pliers, the steel ingot is kept in the heating furnace for 3 hours and turned over 180 degrees. The ingot is returned to the furnace and kept for 1 hour for forging.

[0061] One-time upsetting and drawing: place the steel ingot with pli...

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PUM

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Abstract

The invention discloses a high-homogeneous large-size ultrahigh-strength steel bar comprising the chemical composition by the mass percentage: 0.25-0.40% of C, 0.50-1.50% of Mn, 1.20-2.50% of Si, 0.80-1.20% of Cr, 4.50-6.50% of Ni, 0.40-1.00% of Mo, not more than 0.35% of V, not more than 0.20 % of Nb, not more than 0.005% of S, not more than 0.01% of P, not more than 20 ppm of O, not more than 25 ppm of N, and the balance Fe. At the same time, a production method of the steel bar is also provided; the forging process includes steel ingot heating, first upsetting and stretching, second upsetting and stretching, third upsetting and stretching, and stretching. The high-homogeneous large-size ultrahigh-strength steel bar has excellent mechanical properties; macrostructures comprise that white spots, dark spots, radial segregation and annual ring-shaped segregation all reach an AAAA level, the transverse performance reaches more than 90% of the longitudinal performance and a homogenization effect is achieved.

Description

technical field [0001] The invention relates to the field of ultra-high-strength steel, in particular to a high-homogeneity large-size ultra-high-strength steel bar and a production method for the steel bar. Background technique [0002] In the prior art, the forging method of high-strength steel has the following reports: [0003] (1) CN101920304A A method for forging large steel shaft forgings for the first overall elongation is to heat the forging to the initial forging temperature, use a flat anvil on the forging hammer to elongate, and reach the effective hole welding temperature above 900 ° C. The amount of deformation is 29-31% to eliminate the internal defects of the forging; the overall elongation is to heat the forging to the initial forging temperature, and use a flat anvil on the forging hammer to elongate, and the deformation amount is 15% above the final forging temperature of 800°C. -20%; the single deformation of each segment should not be less than 20% duri...

Claims

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Application Information

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IPC IPC(8): C22C38/44C22C38/46C22C38/48C21D8/06
Inventor 张景海田玉新郭军霞周小弟顾雄陈杰
Owner 宝武特种冶金有限公司
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