Alloys or metallic compositions – Ferrous – Chromium containing – but less than 9 percent
Reexamination Certificate
1999-07-09
2001-10-02
Jones, Deborah (Department: 1775)
Alloys or metallic compositions
Ferrous
Chromium containing, but less than 9 percent
C428S653000, C428S939000, C148S531000, C148S537000
Reexamination Certificate
active
06296805
ABSTRACT:
The invention relates to a coated, hot- and cold-rolled steel sheet comprising a very high resistance after thermal treatment.
In this technical area, the proposed solutions involving an increase in the mechanical characteristics are accomplished to the detriment of shaping properties. There is a solution consisting in separating the shaping properties and those required for use. The characteristics required for use are obtained through a thermal treatment subsequent to or concomitant with shaping. In this case, the proposed sheets are not delivered coated because of problems of holding power of the coating at the time of thermal treatment. Coating therefore is performed on finished castings, which requires a careful cleaning of the surfaces and the hollowed portions. In addition, the thermal treatment must be performed under a controlled atmosphere in order to prevent any decarbonization and oxidation of the metal in the sheet. Steel sheets for thermal treatment do not have any pre-coating which requires post-treatments of scouring, pickling and coating.
At the time of continuous coating of flat hot- and cold-rolled products, preliminary annealing and cooling preceding or following the zinc- or aluminum-based coating operation, are used only to bring the sheet to a temperature close to that of the bath or to restore the mechanical properties of the sheet degraded at the time of cold-rolling. These thermal cycles are chosen in terms of the composition of the steel so that no allotropic transformation takes place at the time of the thermal cycle, the objective being to obtain mechanical characteristics similar to those measured on the steel sheet delivered uncoated.
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Devroc Jacques
Hennechart Jean-Paul
Laurent Jean-Pierre
Spehner Dominique
Jones Deborah
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Savage Jason
Sollac
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