GB489578A - Sheet metal and method of manufacture - Google Patents

Abstract

In a method of treating hot-rolled low-carbon steel sheet or strip, particularly for making tin canisters, the metal is drastically cold rolled to a thickness within 5-25 per cent of the final thickness, is then heat treated at a temperature above the A3 point, i.e. at the temperature above which g -iron is formed, and then cold rolled to final thickness. An ageing treatment may then be applied. In one example hot-rolled steel strip 0,109" thickness is cold rolled to 0,008" and then passed through a continuous furnace, the temperature and speed of travel being arranged so that the strip is heated to about 1700 DEG F., causing re-crystallization in about half a minute. The strip passes from the furnace to a cooling table and a non-oxidizing atmosphere is maintained over the furnace and table. After cold rolling to 0,007" thickness the material, either in strip or sheared into sheets, is passed through a tin bath at a temperature of 500-600 DEG F., which has an ageing effect, or this effect may be produced by heating to about 1200 DEG F., without tinning, or may be omitted when very thin gauges are produced. In another example strip 0,109" thick is cold rolled to 0,0105," heat treated at 1700 DEG F., cold rolled to 0,009" and tinned at 600 DEG F.