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1080mpa grade carbide-free bainite/martensite composite finish-rolled steel bar and production method

A carbide and bainite technology, which is applied in the field of 1080MPa carbide-free bainite/martensite composite finish-rolled steel bars and production, can solve the problem of imperviousness of large-scale steel bars, increased sensitivity to hydrogen embrittlement, and safety problems. Low coefficient and other problems, to achieve the effect of good resistance to delayed fracture, low carbon content, high safety factor

Active Publication Date: 2020-05-29
HEBEI IRON AND STEEL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] At present, there is a quenching and tempering route for the development of ultra-high-strength finish-rolled threaded steel bars, mainly using steel types such as 40Si2Mn and 45Si2Cr, and adopting water penetration (once or multiple times) + medium-high temperature tempering. The disadvantage of this route is that the process is complex and requires Multiple quenching and tempering treatments, and large-scale steel bars have the phenomenon of "hardening through"; too high carbon content, increased susceptibility to hydrogen embrittlement; high yield ratio, low safety factor

Method used

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  • 1080mpa grade carbide-free bainite/martensite composite finish-rolled steel bar and production method
  • 1080mpa grade carbide-free bainite/martensite composite finish-rolled steel bar and production method

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Effect test

Embodiment 1

[0022] Specification Φ25mm, vanadium-containing 1080MPa grade carbide-free bainite ultra-high-strength finish-rolled steel bar, the chemical composition and weight percentage of the finish-rolled steel bar are: C: 0.23%, Si: 1.3%, Mn: 2.0-3.0%, Cr: 0.3 ~0.5%, V: 0.06~0.08%, the balance is Fe and unavoidable impurity elements.

[0023] Production method: 1) Smelt molten steel according to the above-mentioned composition, LF refining of molten steel, and continuous casting of billet to obtain continuous casting billet; 2) Heat continuous casting billet to 1130°C, descale with high-pressure water, rough rolling, intermediate Rolling, finish rolling, natural cooling, and tempering heat treatment to obtain finish-rolled steel bars.

[0024] The rolling start temperature is 1100°C; the finish rolling exit temperature is 1000°C.

Embodiment 2

[0026] Specification Φ32mm, vanadium-containing 1080MPa grade carbide-free bainite ultra-high-strength finish-rolled steel bar, the chemical composition and weight percentage of the finish-rolled steel bar are: C: 0.25%, Si: 1.4%, Mn: 2.0-3.0%, Cr: 0.5 ~0.8%, V: 0.08~0.10%, the balance is Fe and unavoidable impurity elements.

[0027] Production method: 1) Smelt molten steel according to the above-mentioned composition, LF refining of molten steel, and continuous casting of billet to obtain continuous casting billet; 2) Heat continuous casting billet to 1150°C, descale with high-pressure water, rough rolling, Rolling, finish rolling, natural cooling, and tempering heat treatment to obtain finish-rolled steel bars.

[0028] The rolling start temperature is 1130°C; the finish rolling exit temperature is 1030°C.

Embodiment 3

[0030] Specification Φ36mm, vanadium-containing 1080MPa grade carbide-free bainite ultra-high-strength finish-rolled steel bar, the chemical composition and weight percentage of the finish-rolled steel bar are: C: 0.26%, Si: 1.5%, Mn: 2.0-3.0%, Cr: 0.6 ~0.9%, V: 0.08~0.10%, the balance is Fe and unavoidable impurity elements.

[0031] Production method: 1) Smelt molten steel according to the above-mentioned composition, LF refining of molten steel, and continuous casting of billet to obtain continuous casting billet; 2) Heat continuous casting billet to 1150°C, descale with high-pressure water, rough rolling, Rolling, finish rolling, natural cooling, and tempering heat treatment to obtain finish-rolled steel bars.

[0032] The rolling start temperature is 1130°C; the finish rolling exit temperature is 1020°C.

[0033] Table 1 Strength and toughness index of steel bar

[0034]

[0035]

[0036] Note in the table: A: Elongation after breaking, %; Agt: Total elongation at...

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Abstract

The invention discloses a 1080MPa carbide-free bainite / martensite complex-phase finish rolling reinforcement and a production method, and relates to the field of metal material processing. The finishrolling reinforcement is prepared from the following chemical components according to weight percent: 0.23 to 0.27% of C, 1.2 to 1.6% of Si, 2.0 to 3.0% of Mn, 0.3 to 1.0% of Cr, 0.06 to 0.10% of V and the balance of Fe and inevitable impurity elements. The production method comprises the following steps of smelting in a convertor, performing LF refining, continuously casting square billets, heating the square billets, descaling with high-pressure water, rolling, naturally cooling and performing tempering heat treatment. The finish rolling reinforcement has the advantages of low carbon content, high hydrogen embrittlement susceptibility and delayed fracture resistant capability, low yield ratio and high safety factor, and a metallographic structure is a carbide-free bainite / martensite complex-phase structure; the production method has the advantage of simple process.

Description

technical field [0001] The invention relates to the field of metal material processing, in particular to a 1080MPa grade carbide-free bainite / martensite composite finish-rolled steel bar and a production method. Background technique [0002] At present, there is a quenching and tempering route for the development of ultra-high-strength finish-rolled threaded steel bars, mainly using steel types such as 40Si2Mn and 45Si2Cr, and adopting water penetration (once or multiple times) + medium-high temperature tempering. The disadvantage of this route is that the process is complex and requires Multiple quenching and tempering treatments, and the phenomenon of "impermeable quenching" in large-scale steel bars; too high carbon content, increased susceptibility to hydrogen embrittlement; high yield-to-strength ratio, low safety factor. [0003] In addition, it is the main technical problem to improve the plasticity and toughness of vanadium-containing 1080MPa grade finish-rolled stee...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/02C22C38/24C22C38/38C21D1/25C21D9/52
CPCC21D1/25C21D9/52C21D2211/002C21D2211/008C22C38/02C22C38/24C22C38/38
Inventor 白瑞国白秉哲马海峰乔国平高古辉王宝华张俊粉王立军靳刚强
Owner HEBEI IRON AND STEEL