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US 2009/0065103 A1Published application
Method and apparatus for improved formability of galvanized steel having high tensile strength
OwnerPertti J. Sippolainventor
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OwnerPertti J. Sippolainventor
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The present invention is directed to a method and apparatus of producing a dual-phase galvanized steel strip with improved formability while maintaining a high tensile strength. The present invention comprises a step of cooling and a step of reheating. In the cooling step, the galvanized steel strip has a temperature reduction of from about 300° C. to about 150° C.-250° C. This step of cooling should cool to a maximum extent of about 150° C. different between the initial temperature and the final temperature. This cooling may be accomplished by a hot water quench, or the use of a cooling tower, or other means. The step of reheating should follow the step of cooling. The step of reheating should heat the galvanized steel strip to a temperature of about 340°-390° C. This reheating causes the martensite in the galvanized steel strip to be tempered at a relatively low temperature, which reduces the Fe—Zn phase formation in the GI-coating.
A process of making a galvanized steel strip comprising the steps of
A process of making a galvanized steel strip comprising the steps of
An apparatus for making a galvanized steel strip comprising
A galvanized steel strip comprising a TRIP-aided steel with a carbon equivalent of less than about 0.25% and a retained austentite of from about 4% to about 8%.
A galvanized steel strip comprising a dual-phase steel wherein said strip does not comprise austentite.
Dependencies are inferred from the claim text.