Preanneal rinse process for inhibiting rust on steel strip

• US 3,919,000 A
• Filed: 06/15/1973
• Issued: 11/11/1975
• Est. Priority Date: 06/15/1973
• Status: Expired due to Term

• Current Assignee: Elf Atochem North America, Inc. (Totalenergies Se)
• Original Assignee: Robert Warren Yarrington
• Inventors: Yarrington, Robert Warren
• Primary Examiner(s): Lovell, C.
• Application Number:
  US05/370,497
• Time in Patent Office: 879 Days
• Field of Search: 148/4,6.14,13.1,14,15,18,31.5,20.6,27 117/49,127 134/2,19
• US Class Current: 148/633
• CPC Class Codes: C21D 1/70 while heating or quenching
• CPC Class Codes: C23F 11/08 in other liquids
• CPC Class Codes: C23F 11/18 using inorganic inhibitors
• CPC Class Codes: C23F 11/181 Nitrogen containing compounds
• CPC Class Codes: C23F 11/187 Mixtures of inorganic inhibitors
• CPC Class Codes: Y02P 10/20 Recycling

Abstract

Cold rolled steel strip is treated, prior to annealing, with a dilute aqueous rinse solution containing soluble calcium salt or a soluble ferricyanide or ferrocyanide salt or a mixture of soluble calcium salt with sodium nitrite or soluble ferricyanide or soluble ferrocyanide. The residues of said rinses inhibit rust formation on the annealed strip during storage and transit.

Claims

1. A PROCESS FOR INHIBITING RUST FORMATION ON COLDROLLED STEEL STRIP WHICH COMPRISES CONTACTING THE STRIP, PRIOR TO ANNEALING WITH AN AQUEOUS DILUTE RINSE SOLUTION CONTAINING AN EFFECTIVE RUST-INHIBITING AMOUNT OF A MIXTURE OF CALCIUM ION AN SODIUM NITRITE, THE CALCIUM ION BEING SUPPLIED BY A SOLUBLE CALCIUM SALT HAVING A SOLUBILITY IN WATER OF AT LEAST 1.88G/LITER OF CA++ ION AND BEING FREE OF CORROSION-PROMOTING ANIONS SELECTED FROM THE CLASS CONSISTING OF SULFATE AND CHLORIDE, WHEREIN THE CONCENTRATION OF CALCIUM ION IN THE SOLUTION IS FROM ABOUT 0.25 TO 3 OZ. PER GALLON AND THE CONCENTRATION OF SODIUM NITRITE IS FROM ABOUT 0.13 TO 3 OZ. PER GALLON, DRYING THE STEEL STRIP AND ANNEALING THE STRIP IN A REDUCING GAS ATMOSPHERE.

2. A process for inhibiting rust formation on cold-rolled steel strip which comprises contacting the strip, prior to annealing, with an aqueous dilute rinse solution containing an effective rust-inhibiting amount of a mixture of calcium ion and ferricyanide or ferrocyanide ion, the calcium ion being supplied by a soluble calcium salt having a solubility in water of at least 1.88 g/liter of Ca ion and being free of corrosion -promoting anions selected from the group consisting of sulfate and chloride, wherein the concentration of calcium ion in the solution is from about 0.25 to 3 oz. per gallon and the concentration of ferricyanide ion or ferrocyanide ion is from about 0.13 to 3 oz. per gallon, drying the steel strip and annealing the strip in a reducing gas atmosphere.

3. The process according to claim 1 wherein the calcium salt is selected from the group consisting of calcium acetate, calcium benzoate, calcium butyrate, calcium chromate, calcium ferrocyanide, calcium ferricyanide, calcium formate, calcium fumarate, calcium d-gluconate, calcium glycerophosphate, calcium isobutyrate, calcium iodide, calcium lactate, calcium Alpha -methylbutyrate, calcium nitrate, calcium nitrite, calcium propionate, calcium salicylate, calcium dithionate, calcium maleate and calcium valerate.

4. The process according to claim 2 wherein the calcium salt is selected from the group consisting of calcium acetate, calcium benzoate, calcium butyrate, calcium chromate, calcium ferrocyanide, calcium ferricyanide, calcium formate, calcium fumarate, calcium d-gluconate, calcium glycerophosphate, calcium isobutyrate, calcium iodide, calcium lactate, calcium Alpha -methylbutyrate, calcium nitrate, calcium nitrite, calcium propionate, calcium salicylate, calcium dithionate, calcium maleate and calcium valerate.

5. The process according to claim 4 wherein the ferricyanide or ferrocyanide ion is supplied by a salt selected from the group consisting of ammonium ferricyanide, ammonium ferrocyanide, calcium ferricyanide, calcium ferrocyanide, magnesium ferrocyanide, potassium ferricyanide, potassium ferrocyanide, sodium ferricyanide, sodium ferrocyanide and strontium ferrocyanide.