26-04-1972 дата публикации
Номер: GB1271959A
1,271,959. Casting composite rolls. HITACHI Ltd. 23 July, 1969 [26 July, 1968; 20 Jan., 1969], No. 37165/69. Heading B3F. A method of making a composite roll comprises positioning a hollow cylindrical partition member in a mould, pouring molten steel into the annular space between the partition member and the mould walls, pouring molten iron or steel into the interior of the partition member, machining the roll and subsequently subjecting the finished roll to a heat treatment. A carbon film may be formed on the surface of the partition member or the surface may be subjected to nitrification or aluminization to facilitate the metallurgical connection between the member and the other parts of the roll. The wall thickness of the partition member varies along its length and it may be mdae up of a plurality of sections welded together. Its surface may have recesses or projections thereon. The outer part of the roll is made from a high alloy steel containing 0À2 to 2-6% of carbon and at leats 3% of alloying elements such as Ni, Cr, Mo, V, Ti, W, Si and Mn; and the inner part and partition member from plain carbon steel, low alloy steel or cast iron. The partition member may extend beyond the body of the roll so as to form the surface of the roll journal. The tensile strength of the partition member is at least 35 kg/mm.<SP>2</SP>, and that of the metallurgical bonds between the partition member and the other parts at least 7 kg/mm.<SP>2</SP>
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