700MPa grade twisted steel and production method thereof

A threaded steel bar and manufacturing method technology, applied in the field of iron and steel metallurgy and steel rolling, can solve the problems of high alloy cost, welding difficulty, high cost, etc., and achieve the effects of lowering the dissolution temperature, facilitating precipitation and precipitation, and improving strength and plasticity

Active Publication Date: 2014-07-02
INST OF RES OF IRON & STEEL JIANGSU PROVINCE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, there are a small number of 700MPa-grade steel bars researched by laboratories in China, but there are problems such as high alloy cost and difficult welding that greatly limit the promotion of high-strength steel bars. The chemical composition of steel bar is: C:0.20~0.25, Si:0.40~0.80, Mn:1.20~1.60, P≤0.035, S≤0.035, V:0.06~0.20, N:0.010~0.030, Ni:0.20~2.0, Cr: 0.20 ~ 2.0, Ti: 0.01 ~ 0.03, combined with its embodiment Cr, Ni content is the middle limit of the composition range, it can be seen that

Method used

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  • 700MPa grade twisted steel and production method thereof
  • 700MPa grade twisted steel and production method thereof
  • 700MPa grade twisted steel and production method thereof

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] It is smelted by converter, refined by LF, and continuously cast into 150mm×150mm billets; the heating temperature of the soaking section in the heating furnace is 1170-1250°C; The rolling temperature is 1050-1080 ℃, after rough rolling, middle rolling, and after a period of water cooling, it enters finishing rolling. The bed is naturally cooled to room temperature to obtain 700MPa grade rebar. The chemical composition of the steel bar is: C0.29%, Si0.72%, Mn1.51%, V0.19%, Nb0.03%, Ni0.04%, N220ppm, Ti0.02%. Table 1 shows the mechanical properties, yield strength> 700MPa, tensile strength> 850MPa, elongation after fracture> 14%, the structure is ferrite and pearlite, specific as figure 1 shown.

[0021] Table 1 Mechanical properties of ∮20mm700MPa grade steel bars

[0022]

Embodiment 2

[0024] It is smelted by converter, refined by LF, and continuously cast into 150mm×150mm billets; the heating temperature of the soaking section in the heating furnace is 1170-1220℃; the rolling is carried out by a continuous bar and wire rolling mill, the rolling specification is ∮25mm, and the opening The rolling temperature is 1060-1080 ℃, after rough rolling, middle rolling, and after a period of water cooling, it enters the finishing rolling. The bed is naturally cooled to room temperature to obtain 700MPa grade rebar. The chemical composition of the steel bar is: C0.31%, Si0.72%, Mn1.51%, V0.23%, Nb0.03%, Ni0.04%, N230ppm, Cu0.05%. Table 2 shows the mechanical properties, yield strength> 700MPa, tensile strength> 850MPa, elongation after fracture> 14%.

[0025] Table 2 Mechanical properties of ∮25mm700MPa grade steel bars

[0026]

[0027]

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Abstract

The invention provides a 700MPa grade twisted steel and a production method thereof. The twisted steel comprises the following basic components: 0.28-0.32% of C, 0.40-0.80% of Si, 1.20-1.60% of Mn, 0.18-0.24% of V, 0.02-0.06% of Nb, 0.02-0.10% of Ni, 200-300ppm of N, and the balance of Fe and inevitable impurities, and optionally comprises any one or more than two of 0.001-0.020% of Ti, 0.01-0.05% of Mo and 0.02%-0.10% of Cu. The twisted steel is produced by a process comprising smelting in a converter or an electric furnace, refining in an LF (Ladle Furnace), continuous casting and continuous rolling of billets and cooling by using a cooling bed. The twisted steel produced from the components by the method has the lower yield strength of greater than 700MPa and the percentage elongation after fracture of greater than 14%; the microscopic structure of the twisted steel comprises ferrites and pearlites.

Description

technical field [0001] The invention relates to a 700MPa grade threaded steel bar and a production method thereof, belonging to the fields of iron and steel metallurgy and steel rolling. Background technique [0002] Construction steel bars account for a large proportion of the total steel output, while low-strength grade steel bars are used in a relatively high proportion, which will adversely affect the safety level of buildings and energy conservation and consumption reduction in the steel industry. With the development of economy, steel bars will develop in the direction of higher strength grade, multi-functionality and high quality. At present, the newly revised national standard has added 600MPa steel bar, making the existing national standard reach the international advanced level. But at the same time, it should be noted that 400MPa and above steel bars have been mainly used in foreign countries. At the same time, 500MPa steel bars are being promoted. The promotion ...

Claims

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Application Information

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IPC IPC(8): C22C38/16C22C38/14C22C38/12C21D8/08
Inventor 李阳麻晗黄文克张建春
Owner INST OF RES OF IRON & STEEL JIANGSU PROVINCE
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