Grading control cooling process of 600Mpa-grade high-strength anti-seismic weather-proof hot-rolled steel bar

A cooling process and hierarchical control technology, applied in the direction of temperature control, etc., can solve the problems of high C content, poor weather resistance, and inability to ensure the strength-to-yield ratio of seismic indicators

Active Publication Date: 2020-04-28
CENT IRON & STEEL RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] The 600MPa high-strength seismic and weather-resistant steel bar is a trend in the development of hot-rolled steel bars. At present, the 600MPa hot-rolled steel bars developed in China are all produced by converter or electric furnace smelting + billet continuous casting + continuous rolling + cooling bed air cooling. V, Nb, Ti, B, Mo and other elements are added in the composition and the C content is relatively high (>0.25%). Air cooling is used without fully combining controlled rolling and controlled cooling technology, and the weather resistance effect is poor
Because the cooling rate of the water piercer is not easy to control accurately, the seismic index strength-to-yield ratio cannot be guaranteed to be > 1.25 after using the water piercing cooling process, so it can only be air-cooled after rolling between the finishing mill and the double-length shear, and dare not use the water piercer Controlled cooling equipment and controlled cooling process

Method used

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  • Grading control cooling process of 600Mpa-grade high-strength anti-seismic weather-proof hot-rolled steel bar
  • Grading control cooling process of 600Mpa-grade high-strength anti-seismic weather-proof hot-rolled steel bar
  • Grading control cooling process of 600Mpa-grade high-strength anti-seismic weather-proof hot-rolled steel bar

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] (1) The internal control chemical composition of the test steel bar: C 0.22%, Si 0.50%, Mn 1.42%, P 0.028%, S0.021%, Cr 0.15%, V 0.16%, N 280ppm; Fe balance.

[0023] (2) After conventional heating of 160 square billets, hot rolling is carried out. The rolling specification is Φ25mm, the billet heating temperature is 1150°C, the billet exit temperature is 1100°C, and the rolling start temperature is 1050°C. Rough rolling, intermediate rolling, and intermediate rolling The cooling between finishing and finishing rolling is mainly based on water tank rapid cooling, the average cooling speed is controlled at 20°C / s, the finishing rolling speed is 14m / s, and the finishing rolling temperature is controlled at 1050°C;

[0024] (3) Adopt the step-by-step control cooling process of fast cooling-returning temperature-fast cooling-returning temperature cycle, the total cooling time is controlled in stages for 1.5s, and the minimum temperature is adjusted according to the CCT curve...

Embodiment 2

[0027] (1) The internal control chemical composition of test steel bar HRB600E: C 0.20%, Si 0.50%, Mn 1.50%, P0.0024%, S 0.028%, V 0.10%, N243ppm, Cr0.5%, Ni0.9%; quantity.

[0028] (2) After conventional heating of 150 square billets, hot rolling is carried out. The rolling specification is Φ25mm. The cooling between rolling and finishing rolling is mainly based on water tank rapid cooling, the average cooling speed is controlled at 40°C / s, the final rolling speed is 14m / s, and the final rolling temperature is controlled at 900°C;

[0029] (3) Adopt the stepwise controlled cooling process of fast cooling-returning temperature-fast cooling-returning temperature cycle, control the total cooling time in stages to 2s, adjust the minimum temperature ≥ 550°C according to the CCT curve and precipitation curve, and the maximum surface cooling speed V cooling At 175°C / s, control the temperature of the cooling section to be in the optimum temperature zone of the pearlite phase transfo...

Embodiment 3

[0032] (1) The internal control chemical composition of test steel bars: C 0.24%, Si 0.65%, Mn 1.55%, P 0.028%, S0.021%, Cr 0.2%, V 0.014%, N 200ppm, Ni0.5%; Fe balance .

[0033] (2) After conventional heating of 160 square billets, hot rolling is carried out. The rolling specification is Φ12mm, the billet heating temperature is 1150°C, the billet exit temperature is 1100°C, and the rolling start temperature is 1050°C. Rough rolling, intermediate rolling, and intermediate rolling The cooling between finishing and finishing rolling is mainly based on water tank rapid cooling, the average cooling speed is controlled at 30°C / s, the finishing rolling speed is 15m / s, and the finishing rolling temperature is controlled at 900°C;

[0034] (3) Adopt the step-by-step control cooling process of fast cooling-returning temperature-fast cooling-returning temperature cycle, the total cooling time is controlled in stages to 0.8s, and the minimum temperature is adjusted according to the CCT ...

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Abstract

The invention relates to a grading control cooling process of a 600Mpa-grade high-strength anti-seismic weather-proof hot-rolled steel bar and belongs to the technical field of a new steel process. The control cooling process belongs to a whole-process grading control cooling process and is combined with cooling path control on the basis of the original air cooling, and composite enhancement of cooling among mills, cooling after precision rolling and the whole-process cooling process on a cooling bed is emphasized, so that fine pearlite mass size and small interlamellar spacing are achieved, the precipitation enhancing effect of microalloy elements is improved, and the best composite enhancement effect of the 600Mpa-grade high-strength anti-seismic weather-proof hot-rolled steel bar is achieved.

Description

technical field [0001] The invention belongs to the technical field of new iron and steel technology, and in particular provides a hierarchically controlled cooling process for 600MPa-level high-strength earthquake-resistant and weather-resistant hot-rolled steel bars. Background technique [0002] The 600MPa high-strength seismic and weather-resistant steel bar is a trend in the development of hot-rolled steel bars. At present, the 600MPa hot-rolled steel bars developed in China are all produced by converter or electric furnace smelting + billet continuous casting + continuous rolling + cooling bed air cooling. V, Nb, Ti, B, Mo and other elements are added in the composition and the C content is high (>0.25%). Air cooling is used without fully combining controlled rolling and controlled cooling technology, and the weather resistance effect is poor. In order to reduce the addition of microalloying elements and ensure that the strength, plasticity, and corrosion resistance...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/38C22C38/58C22C38/24C22C38/46C22C38/28C22C38/26C22C38/50C22C38/48C21D8/08B21B37/74B21B37/76
CPCC22C38/02C22C38/04C22C38/38C22C38/58C22C38/24C22C38/46C22C38/28C22C38/26C22C38/50C22C38/48C21D8/08B21B37/74B21B37/76C21D2211/009C21D2211/004C21D2211/005
Inventor 王卫卫肖金福白宇冯光宏刘鑫张宏亮
Owner CENT IRON & STEEL RES INST
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