Patent ID: 6199263
Filing Date: 2001-03-13
Classification: C23D,Y10T

Abstract:
A process for the preparation of an enameled sheet steel, comprising:performing the following steps on a steel sheet in the following order:scouring followed immediately by treating of a surface of said scoured steel sheet for temporary protection against corrosion and for prelubrication;shaping of said treated steel sheet followed by cleaning of said surface of said shaped steel sheet;nickeling of said surface of said cleaned steel sheet; anddirect enameling of said surface of said nickeled steel sheet;wherein said treating for temporary protection against corrosion and for prelubrication meets the following criteria a)-c), when it is applied after scouring on a bare sheet steel with a thickness of 1 mm and gradation DC 03 ED or DC 04 ED by reference to EN standard 10209 (November, 1996):a) Criterion for resistance to corrosion: the surface of said 1 mm thick bare sheet steel scoured and then treated for temporary protection against corrosion and for prelubrication shows no trace of red rust after 10 cycles in a humidotherm test according to DIN standard 50017 (October, 1982);b) Criterion for lubrication: after stamping of said 1 mm thick bare sheet steel in a shape of a flat-bottomed cupel of a sheet-steel blank with a diameter of 90 mm, followed by scouring and then treating for temporary protection against corrosion and for prelubrication, further stamping without further lubrication over a height of 25 mm at the rate of 1.6 mm/s with a die 50 mm in diameter, occurs without breaking of said blank when a blank-clamp force on the edges of said blank is .ltoreq.65 kN;c) Criterion for cleaning: no significant trace of the treatment for temporary protection against corrosion and for prelubrication is observed after cleaning of the surface of said scoured and then treated 1 mm thick bare sheet steel under the following conditions: immersing for 3 minutes in a bath brought to approximately 60.degree. C. containing 35 g/l of sodium metasilicate, 16 g/l of trisodium phosphate and 2 g/l of nitriloacetic acid, then rinsing with tap water at room temperature by immersing for 1 minute in said tap water followed by spraying of the said tap water for 0.5 minute onto said cleaned surface of said 1 mm thick bare sheet steel.