GB190415220A - Improved Manufacture or Treatment of Armour Plates and other Articles of Steel. - Google Patents

Abstract

15,220. Hadfield, R. A. July 7. Tempering; nickel steel; chromium steel; manganese steel.-Relates to the manufacture of a special armour plate, and to the toughening of steel castings and armour plate generally, the toughening - process being specially applicable to nickel-chromium steel, containing tungsten or not, and the steel described in Specification No. 16,132, A.D. 1901. The object is heated uniformly up to between 950‹ C. and 1100‹ C., cooled in air, reheated to about 700‹ C., cooled slowly in the furnace, again heated to about 700‹ C., cooled slowly to about 640‹ C., and suddenly cooled, either by water or an air blast. It is then reheated to about 600‹ C. and again suddenly cooled. In a modified method, the first re-heating to 700‹ C. is omitted. The special temperatures mentioned may vary as much as twenty degrees and the sudden cooling may not be carried below 250‹ C. After this treatment, the metal may be casehardened in the usual way. A special nickelchromium steel armour plate which is afterwards treated by this process is made from steel described in the above-mentioned Specification, and contains 0À3-0À4 per cent. of carbon, about 0À25 per cent. of manganese, about 1À8 per cent. of chromium, and about 3À3 per cent. of nickel.