Production method for normalizing Q370 qE steel plate for bridge
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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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[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
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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 of normalizing Q370qE steel plates for bridges, the chemical composition weight percent: C 0.130-0.174%, Si 0.15-0.25%, Mn 1.5-1.65%, P≤0.018%, S≤0.005%, V 0.035-0.055%, Nb 0.01-0.03%, Ti 0.005-0.015%, Als 0.015-0.045%, N≤0.012%, CEV 0.40-0.43. The slab heating temperature is ≤1250°C, the starting rolling temperature is ≥1000°C, the final rolling temperature of the first stage, the starting rolling temperature of the second stage and the cumulative reduction rate of the second stage are selected according to the width and thickness of the slab. The normalizing temperature of post-rolling heat treatment is 880±10°C, the total time in the furnace is 1-2min / mm, the heating rate is 1min / mm, air cooling after normalizing. The Q370qE steel plates for bridges produced by the method of the invention can all meet the standard requirements, and the qualified rate of performance is increased from 81% to 99%, which can fully meet the needs of mass production.
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 ...
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Application Information
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