Method for producing deep drawing skin-passed hot-dip galvanizing sheet steel

Abstract

The invention discloses a manufacturing method of deep drawing finish heat galvanized steel sheet, capable of producing the deep drawing finish heat galvanized steel sheet on the continuous heat galvanized line for building materials. The method on the continuous heat galvanized line for building materials uses following technique measures: carbon content of the substrate is controlled in 0.0030 to 0.0060 % by weight percent, Ti* content is controlled in 0.02 to 0.04 % by weight percent; the heat rolling is closed in austenite area near Ar3, after rolling, quickly cooling to 700-780 DEG C, and coiling after cooling 10-15s; annealing in 780-880 DEG C temperature range. Under condition of ensuring r value, the product crystal grain is thinned and the influence of annealing temperature fluctuation to the product crystal grain size is reduced, thereby reducing influence of finish extensibility to the product yield strength and the n value to obtain the deep drawing finish heat galvanized steel sheet with stable and excellent synthesis forming performance.

Description

technical field [0001] The invention relates to a production method of a galvanized steel sheet, in particular to a method for producing a deep-drawing skin-skinned hot-dip galvanized sheet on a continuous hot-dip galvanizing line for building materials. Background technique [0002] The annealing furnace in the continuous hot-dip galvanizing line generally does not have an over-aging section. It is necessary to use ultra-low carbon interstitial-free steel (IF steel) to produce deep-drawn hot-dip galvanized sheets. Requires ultra-low carbon (C≤0.0050%, low nitrogen (N≤0.0030%), final rolling at a temperature above Ar3 (the temperature at which austenite transforms to ferrite) during hot rolling, and high-temperature annealing for hot-dip galvanizing to improve r value (plastic strain ratio), use a smaller skin elongation to reduce the yield strength caused by work hardening, and reduce the n value (work hardening index). For continuous hot-dip galvanizing lines for building ...

AI Technical Summary

Problems solved by technology

IF steel has a higher annealing and recrystallization temperature than carbon aluminum killed steel. To complete the recrystallization annealing online, the unit needs to slow down and raise the temperature. Large fluctuations; for the skin-pass galvanized sheet, the skin-pass machine can only ensure the skin-pass effect of the skin-pass galvanized sheet under a large skin-pass pressure, which often leads to a large skin-pass elongation. In addition, in order to To ensure the quality of the skin-pass mill, it is necessary to adjust the skin-pass parameters according to the strip shape, resulting in large fluctuations in the skin-pass elongation

For IF steel, coarsening the finished grain can increase the r value (plastic strain ratio average value), but when the finished grain is thicker, the influence of the finishing process on performance indicators such as yield strength and n value increases, so for For IF steel skin-finishing hot-dip galvanized sheet, the control of n and r values ​​is contradictory, and the conventional production method of deep-drawing skin-skinned hot-dip galvanized steel sheet cannot be implemented on the continuous hot-dip galvanizing line for building materials

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