Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
  • C21D1/26—Methods of annealing
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
  • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
  • C21D1/68—Temporary coatings or embedding materials applied before or during heat treatment
  • C21D1/70—Temporary coatings or embedding materials applied before or during heat treatment while heating or quenching

Definitions

• the present invention relates to the box-annealing of steel sheet.
• the heat treatment of cold-reduced steel sheet and strip is accomplished either in batch operations or in continuous operations.
• Batch heat treatment may be divided into two categories: (a) open-coil annealing in which a tight coil is first rewound with a suitable spacer in between each wrap of the coil to permit circulation of the furnace atmosphere between the individual wraps to hasten and improve the uniformity of heating, and (b) box annealing in which a large stationary mass of steel (either cut sheet or coils) is subjected to a comparatively longer heat treatment cycle by varying the temperature within the furnace that surrounds it. In the latter, box annealing practices, the mass of steel is slowly raised to the desired annealing temperature and soaked at such temperature for a period of to 24 hours.
• the prior art has resorted to the use of a variety of separating media such as colloidal solutions of alumina or silica, finely divided magnesium oxide particles and the formation of thin oxidizing films on the metal surface.
• the latter technique includes the use of silicate containing washing liquids aids in preventing sticking. This is a practice which has been recommended for many years by manufacturers of commercial cleaning compounds. Although many steel facilities use silicated cleaners, such use has not precluded the serious incidence of coil sticking.
• a method of box-annealing a mass of steel sheet wherein said sheet is electrolytically cleaned in a cleaning solution consisting of silicate or phosphate cleaners, or mixtures thereof, rinsed, dried, coiled and thereafter heated to an annealing temperature in a non-oxidizing atmosphere and soaked at such temperature for a time of at least one-half hour, characterized in that the solution utilized for said rinse contains calcium formate, magnesium formate, calcium acetate or magnesium acetate, or mixtures thereof, in a total concentration 1,500 to 10,000 ppm.
• a cleaning solution consisting of silicate or phosphate cleaners, or mixtures thereof
• Each pack consisted of 12 paired test specimens, with each pair separated by a stainless steel spacer. To simulate the pressure exerted by the wrapping of coils, a 15.2 lb. (6.9 kg) weight was used for each run.
• the test pack was placed in a sealed stainless steel annealing box containing a protective atmosphere of 6% H 2 -94% N 2 with a dew point controlled to minus 40°C by passing the gas mixture through a column of calcium sulfate.
• the annealing box was placed in a furnace and heated to an annealing temperature of 1250°F (677°C) in two hours.
• the residue concentration of said carboxylic acid salts will be within the range 0.5 to 1.2 mg/ft2 (5.4 to 12.9 mg/m 2 ).
• a silicated cleaner e.g. Condition 8
• an effective rinse additive such as a magnesium formate
• silicate levels on clean steel surfaces are important in their effect on sticking during annealing
• the fact that a final rinse with an appropriate additive was effective even after an initial rinse in hard water suggests that silicates, phosphates, and the thermal degradation products of calcium and magnesium formates and acetates all contribute to lower sticking during box annealing, as compared with a steel that does not have these residues on the surface.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
• Heat Treatment Of Strip Materials And Filament Materials (AREA)
• Chemical Treatment Of Metals (AREA)
• Heat Treatment Of Articles (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=23491512

Family Applications (1)

Country Status (8)

Families Citing this family (1)

Family Cites Families (6)

• 1983
  • 1983-05-11 CA CA000427899A patent/CA1198708A/en not_active Expired
  • 1983-05-13 EP EP83302724A patent/EP0094808B1/en not_active Expired
  • 1983-05-13 BR BR8302507A patent/BR8302507A/pt unknown
  • 1983-05-13 DE DE8383302724T patent/DE3361283D1/de not_active Expired
  • 1983-05-13 AU AU14538/83A patent/AU1453883A/en not_active Abandoned
  • 1983-05-13 ES ES522379A patent/ES8404713A1/es not_active Expired
  • 1983-05-13 JP JP58082889A patent/JPS5953635A/ja active Pending
  • 1983-05-13 KR KR1019830002072A patent/KR840004790A/ko not_active Application Discontinuation

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