Process of making cold reduced Al-stabilized steel having high drawability
AssigneeNippon Kokan Kabushiki Kaisha
InventorsKazuo Matsudo, Takayoshi Shimomura
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Abstract
In a two stage cold reducing process, Al-stabilized steel is subjected to a decarburizing treatment as intermediate annealing between the first and second cold reducing, to impart unexpectedly high drawability to Al-stabilized steel, the drawability being more than 2.00 r (Lankford value). Such Lankford value shows that the steel is capable of sustaining any severe press forming.
Claims8
Process of making Al-stabilized steel having high drawability, comprising the steps of
- A. making steel consisting essentially of 0.03% to 0.15% C, 0.02% to 0.07% Sol.Al., and other elements and in quantities contained in ordinary Al-Stabilized steel;
- B. hot rolling said steel at a finishing temperature of more than the Ar.sub.3 point, and at a coiling temperature of less than about 600.degree.C;
- C. first cold reducing said steel at a reduction rate of more than 30%;
- D. first annealing said cold reduced steel at about 780.degree.C wherein said C content is decarburized to less than about 0.01%;
- E. second cold reducing said annealed steel at a reduction rate of more than 30%;
- and
- F. annealing said steel by a recrystallized softening annealing thereby to produce a steel having an r value of about 2.2 to 2.3.
Process of improving Al-stabilized steel comprising 0.03% to 0.15% Carbon and 0.02% to 0.07% Sol.Aluminum, wherein after hot rolling and cold reducing to more than 30%, the starting steel is decarbonized at about 780.degree.C to contain less than 0.01% carbon, and subsequently cold reducing said steel to more than 30% and subjecting said steel to further annealing.
Dependencies are inferred from the claim text.