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Ultra-low carbon bake-hardened steel having aging index of lower than 20MPa and production method of steel

A technology of aging index and bake hardening, which is applied in the field of metal material processing, can solve the problems of short anti-aging time, achieve low aging index and improve the effect of anti-aging performance

Active Publication Date: 2015-04-29
SHOUGANG CORPORATION
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The object of the present invention is to provide an ultra-low-carbon bake-hardening steel with an aging index less than 20 MPa, which solves the problem of strain mark surface defects caused by part stamping due to the short anti-aging time of the existing ultra-low-carbon bake-hardenable steel and its production method

Method used

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  • Ultra-low carbon bake-hardened steel having aging index of lower than 20MPa and production method of steel
  • Ultra-low carbon bake-hardened steel having aging index of lower than 20MPa and production method of steel
  • Ultra-low carbon bake-hardened steel having aging index of lower than 20MPa and production method of steel

Examples

Experimental program
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Embodiment 1

[0047] This embodiment provides a production method of (Nb+Ti) composite added ultra-low carbon bake-hardening steel with an aging index less than 20MPa (AI2 and N 2 Heating to 240°C for 17 seconds in a non-oxidizing atmosphere; the heating section further heats the strip to 770°C for 280 seconds and keeps it for 75s; the slow cooling section cools the strip to 650°C for 21 seconds; the fast cooling section The steel strip is cooled to 380° C. in 4.8 seconds; the aging section is used to cool the strip to 350° C. in 276 seconds; the final cooling section is water cooled to room temperature.

[0048] The performance results of bake-hardened steel after treatment according to the above process are shown in Table 1 and Table 2:

[0049] Table 1 Properties of ultra-low carbon BH steel

[0050]

[0051]

[0052] Table 2 AI value of ultra-low carbon BH steel

[0053]

[0054] The continuously annealed steel plate produced by the invention has a relatively low AI value of ...

Embodiment 2

[0056] The difference between this example and Example 1 is that a method for producing ultra-low carbon bake-hardening steel with an aging index of less than 20 MPa is provided. The chemical composition mass percentage of this steel is: C, 0.0017%; Mn, 0.64%; Si, 0.028%; P, 0.034%; S, 0.007; Alt, 0.036%; Ti, 0.006%; Nb, 0.006%; The hot rolling process of the steel controls the heating temperature: 1250; the final rolling temperature: 890°C; the coiling temperature: 710°C; the cold rolling process controls the cold rolling reduction rate at 82%. Flat elongation is 1.3. Other places are completely consistent with Embodiment 1.

Embodiment 3

[0058] The difference between this example and Example 1 is that it provides a method for producing ultra-low carbon bake-hardening steel with an aging index of less than 20MPa. The chemical composition mass percentage of this steel is: C, 0.0020%; Mn, 0.66%; Si, 0.025%; P, 0.036%; S, 0.009%; Alt, 0.040%; Ti, 0.008%; Nb, 0.008%; The hot rolling process of the steel controls the heating temperature: 1260; the final rolling temperature: 905°C; the coiling temperature: 715°C; the cold rolling process controls the cold rolling reduction rate at 83%. Flat elongation is 1.4. Other places are completely consistent with Embodiment 1.

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Abstract

The invention discloses ultra-low carbon bake-hardened steel having an aging index of lower than 20MPa. The ultra-low carbon bake-hardened steel contains the following chemical components in percentage by mass: 0.0013-0.0025% of C, 0.60-0.7% of Mn, less than or equal to 0.031% of Si, 0.03-0.04% of P, 0.005-0.015% of S, 0.02-0.06% of Alt, 0.003-0.012% of Ti, 0.003-0.01% of Nb, less than or equal to 0.003% of N and the balance of Fe and inevitable impurities. The invention also discloses a method for producing the ultra-low carbon bake-hardened steel having the aging index of lower than 20MPa. According to the ultra-low carbon bake-hardened steel having the aging index of lower than 20MPa and the production method of the steel, on the basis of optimizing the processes of hot rolling, cold rolling, continuous annealing and the like, the produced continuously-annealed steel plate has a low aging index, and therefore, the aging resistance of the product is improved, and the problem of strain mark surface defects of parts during stamping due to relatively short anti-aging time of the ultra-low carbon bake-hardened steel is solved.

Description

technical field [0001] The invention belongs to the field of metal material processing, and in particular relates to an ultra-low-carbon bake-hardening steel with an aging index of less than 20 MPa and a production method thereof. Background technique [0002] Ultra-low carbon bake-hardening steel is a high-quality steel plate for automobiles that has a low yield strength before stamping. plate. The feature of this product is: the organic combination of product strength, deep drawing performance and anti-sag performance of parts has been realized. At the same time, the disadvantage of this product is that if the aging index (AI value> 30MPa), it is easy to cause stamping orange peel when the product is stamped. The aging index of the bake-hardened steel used is greater than 30 MPa. After 2 months of production, stamping strain marks will appear on the parts of the outer panel of the stamped car door, which form an angle of 45 degrees with the deformation direction, whic...

Claims

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Application Information

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IPC IPC(8): C22C38/14C21D8/02
Inventor 尉冬滕华湘刘光明李飞陈斌闻达刘李斌王海全蒋光锐王彦超
Owner SHOUGANG CORPORATION