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Cold rolling baking hardened steel with yield strength 220MPa and production method thereof

A technology of yield strength and bake hardening, applied in the field of cold-rolled bake hardening steel with a yield strength of 220MPa and its production, can solve the problems of strict process requirements, low yield strength, high production cost, etc., and achieve loose process, excellent high strength , the effect of low production cost

Active Publication Date: 2009-08-05
武汉钢铁有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Its disadvantages: low yield strength, high production cost, strict process requirements, and difficult control

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] Yield strength 220MPa grade cold-rolled bake-hardening steel, which is: its composition and weight percentage are: C 0.05, Mn 0.70, P 0.06, Als 0.015, B 0.004, Si 0.04, S 0.01, N 0.001, the rest is Fe and unavoidable impurities.

[0023] The method for producing 220MPa grade cold-rolled bake-hardening steel with yield strength, its steps:

[0024] 1) The slab is heated to 1180°C, and the final rolling is carried out at 860°C, and the rolled thickness is 2.5mm;

[0025] 2) Coiling at 650°C after laminar cooling;

[0026] 3) The hot-rolled steel coil is naturally cooled to 70°C for cold rolling, the total reduction rate is controlled at 85%, and the product thickness is 0.4mm;

[0027] 4) Carry out continuous annealing, and the annealing temperature is controlled at 780°C;

[0028] 5) The steel plate is cooled in the annealing furnace, the temperature drop rate is controlled at 30°C / s, and the temperature of the steel plate after cooling is controlled at 390°C;

[002...

Embodiment 2

[0033] Yield strength 220MPa grade cold-rolled bake-hardening steel, which is: its composition and weight percentage are: C 0.07, Mn 0.55, P 0.045, Als 0.022, B 0.002, Si 0.025, S 0.015, N 0.004, the rest is Fe and unavoidable impurities.

[0034] The method for producing 220MPa grade cold-rolled bake-hardening steel with yield strength, its steps:

[0035] 1) The cast slab is heated to 1220°C, and the final rolling is carried out at 880°C, and the rolled thickness is 3.5mm;

[0036] 2) Coiling at 680°C after laminar cooling;

[0037] 3) Cool the hot-rolled steel coil naturally to 60°C for cold rolling, the total reduction rate is controlled at 80%, and the product thickness is 0.7mm;

[0038] 4) Carry out continuous annealing, and the annealing temperature is controlled at 790°C;

[0039] 5) The steel plate is cooled in the annealing furnace, the temperature drop rate is controlled at 45°C / s, and the temperature of the steel plate after cooling is controlled at 400°C;

[...

Embodiment 3

[0044] Yield strength 220MPa grade cold-rolled bake-hardening steel, which is: its composition and weight percentage are: C 0.085, Mn 0.50, P 0.03, Als 0.03, B 0.0035, Si 0.030, S 0.012, N 0.002, the rest is Fe and unavoidable impurities.

[0045] The method for producing 220MPa grade cold-rolled bake-hardening steel with yield strength, its steps:

[0046] 1) The cast slab is heated to 1230°C, and the final rolling is carried out at 900°C, and the rolled thickness is 4.0mm;

[0047] 2) Coiling at 695°C after laminar cooling;

[0048] 3) Cool the hot-rolled steel coil naturally to 45°C for cold rolling, the total reduction ratio is controlled at 77.5%, and the product thickness is 0.9mm;

[0049] 4) Carry out continuous annealing, and the annealing temperature is controlled at 800°C;

[0050] 5) The steel plate is cooled in the annealing furnace, the temperature drop rate is controlled at 60°C / s, and the temperature of the steel plate after cooling is controlled at 405°C; ...

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Abstract

The invention relates to low alloyed steel and a production method thereof aiming at solving the defects of low yield strength, high production cost, and the like currently. The invention comprises the measures that the cold-rolling, baking and hardening steel with the yield strength of 220MPa contains components and percentages by weight of 0.05-0.10 percent of C, 0.20-0.70 percent of Mn, 0.01-0.06 percent of P, 0.01-0.06 percent of Als, 0.002-0.004 percent of B, less than or equal to 0.04 percent of Si, less than or equal to 0.015 percent of S, less than or equal to 0.005percent of N, and the rest of Fe and unavoidable impurities; and the production method comprises the following steps of heating a casting blank to 1180-1280 DEG C and finishing rolling under the temperature of 860-930 DEG C; adopting laminar cooling to 650-750 DEG C below and coiling; natural cooling to 10-70 DEG C and cold rolling with the total rolling reduction ratio of 66-85 percent; continuous annealing with the temperature of 780-830 DEG C; cooling in an annealing furnace with the temperature drop speed of 30-80 DEG C / second and the temperature of 390-420 DEG C after being cooled; overaging treatment under the temperature of 360-390 DEG C for 180-250 seconds; cooling and tapping with the temperature of 150-170 DEG C; and finally, leveling with the elongation ratio of 1.20-1.60 percent.

Description

technical field [0001] The invention relates to low-alloy steel and a production method thereof, and more belongs to low-alloy steel and a production method thereof applied to interior and exterior covering parts of automobiles. Background technique [0002] Bake-hardening steel has low yield strength in the delivery state, easy to form, and the product has the product characteristics that the yield strength of the steel plate increases after stamping, painting and baking, and has excellent stamping formability, dent resistance and weldability. Since the product characteristics of bake-hardening steel are consistent with the trend of high-strength steel sheets for automobiles, the products are widely used in interior and exterior panels of automobiles. 2) Technical characteristics of bake hardened steel. [0003] At present, the design of bake-hardening steel at home and abroad is mostly used: adding P and microalloying element Nb (or Ti, V compound addition) to ultra-low c...

Claims

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Application Information

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IPC IPC(8): C22C38/04C22C38/00C22C33/04C21D8/02
Inventor 孙方义罗石念段小平涂冬明汪晓川谢华冯冠文
Owner 武汉钢铁有限公司
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