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Production method for normalizing Q370 qE steel plate for bridge

A production method, q370qe technology, applied in the field of metallurgical technology, can solve the problems of small composition adjustment space, troubles, insufficient strength, etc.

Inactive Publication Date: 2017-10-24
ANGANG STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] The Q370qE steel plate for bridges requires high strength (above 370MPa) and good low-temperature impact performance, but the carbon equivalent is also required to be ≤0.43 in the composition. Due to the small adjustment space of the composition, it is easy to cause insufficient strength after rolling + normalizing, thus As a result, the performance pass rate of normalized steel plates is reduced, generally only about 81%, which seriously affects the economic benefits of enterprises, and has become an urgent problem to be solved in the production of normalized Q370qE steel plates for bridges

Method used

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  • Production method for normalizing Q370 qE steel plate for bridge
  • Production method for normalizing Q370 qE steel plate for bridge

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] Embodiment 1: The thickness of the steel plate is 13 mm, and the width is 3000 mm.

[0016] 1. Chemical composition weight percentage: C 0.150%, Si 0.20%, Mn 1.59%, P 0.015%, S0.003%, V 0.045%, Nb 0.02%, Ti 0.010%, Als0.030%, N 0.007%, CEV 0.424.

[0017] 2. Heating and descaling: the slab heating time is 11min / mm, the heating temperature is 1240°C, and the furnace temperature is 1230°C.

[0018] 3. Rolling: The slab rolling temperature is 1050°C, and high-pressure water is used to fully descale during the rolling process. The final rolling temperature of the first stage is 830°C, the rolling start temperature of the second stage is 970°C, and the cumulative reduction rate of the second stage is 58%.

[0019] 4. Heat treatment: normalizing temperature 885°C, total time in the furnace 1.5min / mm, heating rate 1min / mm, air cooling after normalizing.

Embodiment 2

[0020] Embodiment 2: The thickness of the steel plate is 50mm, and the width is 4500mm.

[0021] 1. Chemical composition weight percentage: C 0.160%, Si 0.17%, Mn 1.62%, P 0.012%, S0.004%, V 0.035%, Nb 0.025%, Ti 0.007%, Als0.040%, N 0.010%, CEV 0.412.

[0022] 2. Heating and descaling: the heating time of the slab is 10min / mm, the heating temperature is 1220°C, and the furnace temperature is 1200°C.

[0023] 3. Rolling: The rolling temperature of the slab is 1080°C, and high-pressure water is used to fully remove the scale during the rolling process. The final rolling temperature of the first stage is 850°C, the rolling start temperature of the second stage is 925°C, and the cumulative reduction rate of the second stage is 53%.

[0024] 4. Heat treatment: normalizing temperature 890°C, total time in the furnace 1.3min / mm, heating rate 1min / mm, air cooling after normalizing.

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Abstract

The invention provides a production method for a normalizing Q370 qE steel plate for a bridge. Chemical components include, by weight percent, 0.130%-0.174% of C, 0.15%-0.25% of Si, 1.5%-1.65% of Mn, smaller than or equal to 0.018% of P, smaller than or equal to 0.005% of S, 0.035%-0.055% of V, 0.01%-0.03% of Nb, 0.005%-0.015% of Ti, 0.015%-0.045% of Als and smaller than or equal to 0.012% of N, and CEV is 0.40-0.43. The slab heating temperature is smaller than or equal to 1,250 DEG C, the rolling starting temperature is larger than or equal to 1,000 DEG C, and the first-stage finish rolling temperature, the second-stage rolling starting temperature and the second-stage accumulated reduction rate are correspondingly selected according to the width and thickness of slabs. After rolling, the heat treatment normalizing temperature is 880+ / -10 DEG C, the total time in a furnace ranges from 1 min / mm to 2 min / mm, the temperature rise rate is 1 min / mm, and air cooling is conducted after normalizing. Various performance indexes of the bridge Q370 qE steel plate produced through the method can reach the standard requirement, the performance qualification rate is increased to 99% from the original 81%, and the requirement of mass production can be completely met.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular relates to a production method of a normalized Q370qE steel plate for bridges. Background technique [0002] The Q370qE steel plate for bridges requires high strength (above 370MPa) and good low-temperature impact performance, but the carbon equivalent is also required to be ≤0.43 in the composition. Due to the small adjustment space of the composition, it is easy to cause insufficient strength after rolling + normalizing, thus As a result, the performance pass rate of normalized steel plates is reduced, generally only about 81%, which seriously affects the economic benefits of enterprises, and has become an urgent problem to be solved in the production of normalized Q370qE steel plates for bridges. Contents of the invention [0003] The invention aims to provide a production method of normalizing Q370qE steel plates for bridges, which can meet the standard requirements in ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/12C22C38/14C22C38/04C22C38/02C22C38/06C21D8/02
CPCC22C38/12C21D8/0221C21D8/0247C22C38/001C22C38/02C22C38/04C22C38/06C22C38/14
Inventor 段江涛张坤韩旭罗军
Owner ANGANG STEEL CO LTD
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