Metal treatment – Process of modifying or maintaining internal physical... – Heating or cooling of solid metal
Patent
1996-08-19
1998-04-14
Yee, Deborah
Metal treatment
Process of modifying or maintaining internal physical...
Heating or cooling of solid metal
148651, C21D 802
Patent
active
057387389
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method for manufacturing a cold rolled steel plate used for enamel applications such as a part of microwave oven, gas range, bathtub and interior or exterior panels of building, and more particularly to a method for manufacturing a cold rolled steel plate which never occur fishscale defect being a fatal defect of the enamel coated product, and particularly excellent in an enamel adherence, and suitable for the enamel coated product having a complicated shape.
BACKGROUND ART
Heretofore, in manufacturing an cold rolled steel plate used for the enamel coated product, it has been mainly striven for preventing a fishscale defect by adding a titanium, boron and oxygen into the steel whereby precipitates such as titanium sulfides, titanium nitrides, titanium carbides, boron nitrides or manganese oxide.
These conventional steels have respectively advantages and disadvantages, for instance, in case of titanium added steel, a formability is excellent whereby a manufacturing of the product of complicated shape is easy, but an enamel adherence is more inferior than other steels, and in case of boron added steel, the enamel adherence is excellent, but it has not good formability and anti-fishscale property is more inferior.
And, in case of high oxygen added steel, the enamel adherence is also good but the formability and anti-fishscale property are more inferior, and since an oxygen is added much in the steel, it is easy to occur various surface defects.
DISCLOSURE OF INVENTION
Therefore, the present invention is proposed so as to improve such disadvantages of above described conventional steels, and it is an object of the present invention to provide a method for manufacturing a cold rolled steel plate which has an excellent enamel adherence greatly improved the formability required for a product of complicated shape.
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described more in detail.
The present invention is a method in which, in a method for manufacturing a cold rolled steel plate by utilizing an aluminum killed steel, by weight %, C: less than 0.01%, Mn: 0.1-0.4%, S: 0.03-0.09%, Ti: 0.04-0.1%, N: less than 0.01%, are contained, atomic ratio defined by Ti/(C+N+0.4S) is 1.0-2.0, and remaining part is Fe and other inevitable impurities are included, and hot rolled so as to be finished more than Ar.sub.3 transformation temperature in a finish rolling, and coiled, and then cold rolled by a reduction ratio of 50-85%, and then continuously annealed, whereby a cold rolled steel plate with excellent enamel adherence is obtained.
Hereinafter, numerical value limiting reasons for composition of the present invention will be described more in detail.
In the present invention, in case when a content of carbon is more than 0.01 weight % (hereinafter, just called as `%`), since an amount of solute carbon in the steel is much, a development of texture is obstructed during annealing or an amount of fine titanium carbide is much in order to fix solute carbon as titanium carbide, and thereby ferrite grain is to be fine, and since the formability becomes greatly lowered, the content amount of said carbon is desirable to limit to less than 0.01%.
Said manganese is an element to be added for an object that sulfur is precipitated as a manganese sulfide and to prevent a hot shortness as well as for improving the anti-fishscale property by producing microvoids upon cold rolling by precipitating the manganese sulfide during hot rolling. However, in case when an adding amount of the manganese is less than 0.1%, there is a worry of hot shortness by a sulfur existing in a solid solution state, and in case when the content amount of the manganese is more than 0.4%, an amount of solid solution manganese and number of manganese sulfide become much whereby a recrystallization growth is suppressed upon annealing and thereby the formability is greatly deteriorated, therefore the content amount of said manganese is desirable to limit to 0.1-0.4%. Th
REFERENCES:
patent: 3761324 (1973-09-01), Elias et al.
patent: 3928083 (1975-12-01), Gondo et al.
patent: 5292383 (1994-03-01), Osawa et al.
Kim Sung Ju
Yoon Jeong Bong
Pohang Iron & Steel Co. Ltd.
Research Institute of Industrial Science & Technology
Yee Deborah
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