Method for producing bright stainless steel
DCFirst Claim
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1. A method for producing bright stainless steel comprising:
- a) forming a hot mill band having a dull oxide free surface;
b) cold reducing the hot mill band to form a full hard coil having a shiny surface;
c) subjecting said full hard coil to a continuous anneal at a temperature of 1500°
-1950°
F. in an oxygen containing atmosphere sufficient to form a protective FeCr2 O3 scale;
d) subjecting said annealed coil to a mild non-etching pickling process to remove the scale; and
e) rolling said annealed coil on a temper mill having specially finished rolls configured to impart a surface pattern that replicates an abrasively polished surface.
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Abstract
A method for producing bright stainless steel whereby a hot mill band having a dull oxide-free surface is first formed. The hot mill band is cold reduced to form a full hard coil having a shiny surface. The coil is subjected to continuous annealing at a temperature of 1500°-1950° F. in an oxygen-containing atmosphere sufficient to form a protective FeCr2 O3 scale. The annealed coil is subjected to a mild non-etching pickling process to remove the black scale. The coil is then rolled on a temper mill having specially finished rolls to impart a surface pattern that replicates an abrasively polished surface.
38 Citations
18 Claims
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1. A method for producing bright stainless steel comprising:
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a) forming a hot mill band having a dull oxide free surface; b) cold reducing the hot mill band to form a full hard coil having a shiny surface; c) subjecting said full hard coil to a continuous anneal at a temperature of 1500°
-1950°
F. in an oxygen containing atmosphere sufficient to form a protective FeCr2 O3 scale;d) subjecting said annealed coil to a mild non-etching pickling process to remove the scale; and e) rolling said annealed coil on a temper mill having specially finished rolls configured to impart a surface pattern that replicates an abrasively polished surface. - View Dependent Claims (2, 3, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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4. A method for producing bright stainless steel comprising:
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a) forming a hot mill band having a dull oxide free surface; b) cold reducing the hot mill band to form a full hard coil having a shiny surface; c) subjecting said full hard coil to a continuous anneal at a temperature of 1500°
-1950°
F. in an oxygen containing atmosphere sufficient to form a protective FeCr2 O3 scale;d) subjecting said annealed coil to a mild non-etching pickling process to remove the scale, wherein the mild non-etching pickling process includes air cooling the annealed coil to an intermediate temperature between 800°
F. and 1000°
F. where it is subjected to a molten salt treatment and then air cooling to ambient temperature where the coil is subjected to a mild acid pickle, and wherein the mild acid pickle includes subjecting said annealed coil to at least one of a nitric acid bath and rinse, a sulfuric acid bath and rinse with hydrofluoric concentration of 0.5% or less on either acid bath; ande) rolling said annealed coil on a temper mill having specially finished rolls configured to impart a surface pattern that replicates an abrasively polished surface.
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14. A method for producing bright stainless steel from a cold reduced, full hard coil, comprising the steps of:
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subjecting the full hard coil to a continuous anneal at a temperature of 1500°
-1950°
F. in an oxygen containing atmosphere to form an FeCr2 O3 containing scale on the annealed coil;pickling the annealed coil with a mild non-etching pickling process to remove the scale, wherein the pickling process includes treating the annealed coil with an acid bath including at least one of nitric and sulfuric acid, the acid bath having a hydrofluoric acid content of less than 0.5%; and rolling the descaled coil on a temper mill having specially finished rolls such that a surface pattern is imparted to the rolled coil which replicates an abrasively polished surface. - View Dependent Claims (15, 16, 17, 18)
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Specification