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800 MPa level hot-rolled threaded steel bar and production method

A technology of threaded steel bars and production methods, applied in the field of iron and steel metallurgy

Active Publication Date: 2019-07-05
INST OF RES OF IRON & STEEL JIANGSU PROVINCE +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

800MPa grade hot-rolled rebar has not been reported

Method used

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  • 800 MPa level hot-rolled threaded steel bar and production method
  • 800 MPa level hot-rolled threaded steel bar and production method
  • 800 MPa level hot-rolled threaded steel bar and production method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0045] The chemical composition of the 800MPa grade hot-rolled rebar in this example is: C 0.18wt%, Si 0.85wt%, Mn1.30wt%, Nb 0.02wt%, Ti 0.05wt%, Mo 0.12wt%, Cr 0.59wt%, B 0.009wt% %, Cu0.03wt%, the rest is Fe and unavoidable impurities, Ceq=0.54.

[0046] Converter smelting, LF refining, continuous casting into 150mm×150mm billet; the temperature of the soaking section of the billet in the heating furnace is 1150-1200°C, and the total heating time is 70min; after that, the continuous rod rolling machine is used for rolling. The manufacturing specification is Ф22mm, the starting rolling temperature is 1020-1050°C, the temperature of the upper cooling bed is 680-730°C, and the 800MPa grade threaded steel bar is obtained by natural cooling to room temperature. The structure of the prepared steel bar is bainite and ferrite, and the proportion of the bainite structure is 81%.

[0047] Table 1 shows the mechanical properties of steel bars, yield strength > 800MPa, tensile strengt...

Embodiment 2

[0051] The chemical composition of the 800MPa grade hot-rolled rebar in this example is: C 0.17wt%, Si 1.17wt%, Mn1.71wt%, Nb 0.03wt%, Ti 0.02wt%, Mo 0.11wt%, Cr 0.41wt%, B 0.003wt% %, Cu0.05wt%, the rest is Fe and unavoidable impurities, Ceq=0.56.

[0052] Converter smelting, LF refining, continuous casting into 150mm×150mm billet; the temperature of the soaking section of the billet in the heating furnace is 1200-1250°C, and the total heating time is 80min; after that, the continuous rod rolling machine is used for rolling. The manufacturing specification is Φ22mm, the starting rolling temperature is 1050-1080°C, the temperature of the upper cooling bed is 750-780°C, and the 800MPa grade threaded steel bar can be obtained by natural cooling to room temperature. The prepared steel structure is bainite and ferrite, and the proportion of bainite is 85%.

[0053] Table 2 shows the mechanical properties of steel bars, yield strength > 800MPa, tensile strength > 960MPa, elongatio...

Embodiment 3

[0058] The chemical composition of the 800MPa grade hot-rolled rebar in this example is: C 0.16wt%, Si 0.32wt%, Mn1.01wt%, Nb 0.01wt%, Ti 0.12wt%, Mo 0.31wt%, Cr 0.87wt%, B 0.002wt% %, Cu0.07wt%, the rest is Fe and unavoidable impurities, Ceq=0.57.

[0059] Converter smelting, LF refining, continuous casting into 150mm×150mm billet; the temperature of the soaking section of the billet in the heating furnace is 1180-1230°C, and the total heating time is 70min; after that, the continuous rod rolling machine is used for rolling. The manufacturing specification is Φ22mm, the starting rolling temperature is 1060-1090°C, the temperature of the upper cooling bed is 720-750°C, and the 800MPa grade threaded steel bar can be obtained by natural cooling to room temperature. The prepared steel structure is bainite and ferrite, and the proportion of bainite is 83%.

[0060] Table 3 shows the mechanical properties of steel bars, yield strength > 800MPa, tensile strength > 960MPa, elongatio...

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Abstract

The invention discloses an 800 MPa level hot-rolled threaded steel bar and a production method. The high-strength threaded steel bar is composed of following elements including, by weight percent (%),0.15%-0.25% of C, 1.00%-3.00% of Si+Mn, 0.01%-0.04% of Nb, 0.01%-0.20% of Ti, 0.50%-1.50% of Mo+Cr, 0.001%-0.01% of B, 0.01%-0.20% of Cu and the balance Fe and inevitable impurities. Through adding of Nb, Mo, Cr and B, the bainite forming temperature is reduced, and forming of granular bainite good in tenacity is promoted; the high-temperature heating and low-temperature initial rolling combinedtechnology is adopted, Nb plays an effective solid solution role, dispersed Nb (C and N) nanoscale precipitation is formed in the subsequent rolling and cooling process, and the precipitation strengthening effect is good. A threaded steel microscopic structure produced through the above components and technology is ferrite + bainite, and the lower yield strength is larger than or equal to 800 MPa.

Description

technical field [0001] The invention belongs to the field of iron and steel metallurgy, and in particular relates to an 800MPa grade hot-rolled threaded steel bar and a production method. Background technique [0002] The rapid development of China's economy has put forward higher and higher requirements for steel bars for construction. High-strength, earthquake-resistant, and economical steel bars will become the mainstream of the market. Improving the strength of rebar can reduce the use of rebar, reduce the density of steel bars and save construction space, which is conducive to the reduction of energy consumption and the improvement of the environment. The national standard GB / T1499.2-2018 "Steel for Reinforced Concrete Part II: Hot-rolled Ribbed Steel Bars" added 600MPa-grade steel bars and canceled 335MPa-level steel bars. It can be predicted that the rebar is developing towards a higher strength level. [0003] At present, the domestic mass-produced and applied hot-...

Claims

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Application Information

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IPC IPC(8): C22C38/02C22C38/04C22C38/26C22C38/28C22C38/22C22C38/32C22C38/20C22C38/38C21D8/08
CPCC21D8/065C21D8/08C21D2211/002C21D2211/005C22C38/02C22C38/04C22C38/20C22C38/22C22C38/26C22C38/28C22C38/32C22C38/38
Inventor 杨晓伟麻晗张宇陈焕德周云
Owner INST OF RES OF IRON & STEEL JIANGSU PROVINCE
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