GB925065A - Method of making tin plate - Google Patents

Abstract

925,065. Thermal treatment of tin plate. UNITED STATES STEEL CORPORATION. Dec. 7, 1961, No. 43902/61. Class 41. Electro-tinned low-carbon steel strip is heated, during forward travel after tinning, to a temperature above the melting-point of tin to form a limited amount of tin-iron alloy determined by quenching the strip to a temperature substantially below said melting-point to arrest further alloy formation; the strip is then again heated during further travel to a temperature above said melting-point to form further additional tin-iron alloy followed by quenching to atmospheric temperature. The first thermal treatment causes iron-tin alloy to form at scattered points on the surface of the strip whereas the second thermal treatment causes said alloy to form at further scattered points other than said first-mentioned points, whereby the resulting tin-plate has a more nearly uniform distribution of iron-tin alloy over the surface thereof. The first heating is controlled to cause the formation of alloy containing 0.03-0.06 1b./bb. of tin and the second heating is controlled to produce a total alloy containing 0.06-0.12 1b./bb. of tin. Tin-plate strip 10 runs over guide rollers 11, 12, 13 and 14. The first heating unit is positioned in the strip path between rollers 12 and 13 and is preferably a high-frequency inductive heating coil; this is followed by quench means 16. The portion of the strip between guide rollers 12 and 14 is heated by the electrical resistance of the strip from current supplied via connections 17. Typically the inductor coil heats the strip to abut 500‹ F. at a position between rollers 12 and 13 which temperature is reduced to about 200 ‹ F. by prompt quenching; and just before entry into the water quench bath 18 a temperature of about 550‹ F. is achieved by resistor heating.