Secondary cold-rolled high-hardness stamping steel with high isotropy and manufacturing method thereof

Abstract

The invention relates to a secondary cold-rolled sheet with high hardness and plane isotropy and a manufacturing method thereof, which are particularly suitable for steel for making an unscrewing cover, a shallow drawn can and the like with low earing requirements. The secondary cold-rolled sheet comprises the following chemical element components in percentage by weight: 0.02 to 0.06 percent of C, less than or equal to 0.03 percent of Si, 0.10 to 0.30 percent of Mn, less than or equal to 0.015 percent of P, less than or equal to 0.015 percent of S, 0.03 to 0.10 percent of Al, less than or equal to 0.0035 percent of N and the balance of Fe and inevitable inclusions. The secondary cold-rolled sheet is prepared by the following steps of: pretreating the proportioned materials by using liquid iron; smelting in a converter; performing post-refining by using the converter; hot-rolling; performing acid washing; cold-rolling; continuously annealing; performing secondary cold-rolling; and finishing to obtain finished rolls, wherein a heating temperature is controlled to be less than or equal to 1,180 DEG C during the hot-rolling, the final rolling temperature is more than Ar3, and a coiling temperature is between 620 and 750 DEG C; cold-rolling deformation is controlled to be between 75 and 90 percent, and a continuous annealing temperature is between 640 and 700 DEG C; annealing time is between 50 and 150 seconds; secondary cold-rolling rate is between 15 and 35 percent, and other conditions meet the requirements of the conventional process; and an obtained product has the hardness of HR30T 60 to 80 and the earing rate of less than or equal to 5 percent.

Description

technical field [0001] The invention relates to a high-hardness isotropic steel material produced by secondary cold rolling and its manufacturing method, in particular to a steel used for making unscrewed caps, shallow-drawn cans, etc. . Background technique [0002] Secondary cold-rolled materials are widely used in can bodies and lids in the food packaging industry. The secondary cold-rolled products developed in recent years have become the first choice for steel can manufacturers to reduce costs and ensure quality because of their high strength, extremely thin thickness and certain processing properties. It is generally required that the secondary cold-rolled material has a low ear-making rate after stamping. If the ear-making rate is too high, the curling after stamping will reflect uneven piping or too much cutting waste, resulting in poor quality and waste. The technologies related to the low selvage rate or isotropy of secondary cold-rolled materials have been int...

AI Technical Summary

Problems solved by technology

The main reason is to add Ti and B elements to fix N and hinder recrystallization to reduce anisotropy in continuous annealing. Since the addition of Ti and B increases the recrystallization temperature (annealing temperature is 720-800°C), the production cost is high and continuous The back-through board is poor and the surface quality is deteriorated

Since the secondary cold-rolling rate has a great influence on the anisotropy of the material, the secondary cold-rolled material produced by the above process cannot obtain the effect of low ear production

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