| 摘要 |
<p>A billet [B1-B23] is provided comprising a body [C, 1 10, 110a, 122, 62] of solid steel and a cladding [J] of an alloy comprising stainless steel, nickel-chrome, nickel-copper and copper-nickel alloys. The cladding may be comprised of a square tube in which the body is inserted with an interface [Z] at which the cladding becomes bonded to the body when the billet is heated and rolled or otherwise worked into a ferrous product [F, R, 120, 123]. At least one element [Ea, Et, Em] composed of a mass of finely divided scavenging aluminium, titanium or magnesium, is placed in the tube adjacent the body and separate from the interface. The elements are advantageously compressed into briquettes which scavenge oxygen from residual air at the interface to prevent oxidation of the cladding at the interface. The tube may be closed to prevent gases outside the billet from penetrating to the interface. Alternatively, reliance may be placed on the briquettes to scavenge oxygen from the residual air and also from atmospheric air and furnace gases before they can penetrate to the interface. The ends of the billet are heated up before the tube reaches a temperature at the interface at which oxidation starts. The briquettes of aluminium or magnesium [Ea, Em] melt before the billet reaches its rolling temperature and a further element [Ea] of finely divided carbon steel may then be inserted between these briquettes and the steel body to prevent the molten metal from penetrating to the interface. In an open tube, an additional element [Eu] composed of ammonium chloride or urea may be inserted between the carbon steel briquette and steel body. The additional element disassociates at a low temperature to scour residual gases out of the interface. The elements can be placed directly in the tube or in a cartridge [60-60g] which is subsequently welded to the tube.</p> |
