GB1142552A - Grain-oriented iron and steel and method of making same - Google Patents

Abstract

1,142,552. Making sheets; working at specified temperatures. ARMCO STEEL CORP. 11 Nov., 1966, No. 50579/66. Headings B3A and B3V. [Also in Division C7] Low-carbon steel and ingot iron sheet having carbon up to 0À1%, manganese 0À01 to 0À40% and sulphur up to 0À05%, or such materials additionally having silicon up to 1À8%, are produced with either a (110), [001] or a (112), [110] preponderant orientation by hot-rolling, coldrolling, and subjecting the cold-rolled stock to a final anneal the first stage of which effects grain growth in the presence of sulphur, selenium or a decomposable compound of one of these and is followed by a secondary recrystallization under box annealing conditions at 1550-1650‹ F. To produce a (112), [100] orientation the cold reduction should be in excess of 90%, whereas a reduction of less than 90% will result in a (110), [001] orientation. The preferred finishing temperature for hot rolling is above 1600‹ F., with coiling at less than 1300‹ F., in order to obtain a fine grain size; alternatively it may be necessary to follow hot-rolling with a normalizing treatment at a temperature above 1625‹ F., preferably at 1800‹ F. Inter-stage annealing, if required during cold rolling, is carried out at 1100- 1800‹ F., while the stock is preferably decarburized, e.g. 1500‹ F. preferably after coldrolling, but possibly prior thereto. By treating the stock in the form of an open coil, the decarburizing primary and secondary recrystallization anneals may be carried out in the same furnace, the atmosphere and temperature being changed as necessary. Sulphur may be provided during the final anneal by incorporating elemental sulphur in the annealing separator (which may be magnesia, alumina, titanium oxide, calcium oxide or other refractory oxide) in an amount of ¢ to 10% by weight of the separator, or by incorporating an equivalent amount of a decomposable sulphur compound; alternatively a gaseous compound such as hydrogen sulphide, sulphur dioxide or sulphur hexafluoride may be present in the furnace atmosphere, to the extent of not less than 750 p.p.m. of hydrogen sulphide or its equivalent. In a further modification hydrogen sulphide may be added to the decarburizing atmosphere under such conditions that a surface layer of iron sulphide is formed of thickness 0À02 mil to 0À1 mil, from which sulphur is subsequently diffused into the grain boundaries during the subsequent final annealing step.