GB1301677A - - Google Patents

Abstract

1301677 Continuous casting; making wire; drawing W J BUEHLER 31 Dec 1969 [31 Dec 1968] 54299/69 Headings B3A B3F and B3P [Also in Division F4] TiNi base alloy, containing from 50-64% by weight of Ni as disclosed in Specification 1,020,872 and including TiNi base alloys in which Co is substituted for some of the Ni as described in Specification 1,202,404, is heated in an environment, e.g. a vacuum, inert to the alloy, in a graphite crucible 11, the molten alloy being forced through an orifice 14, 18 in the die while a metal body part 15 of the die, e.g. of Mo or W, is cooled so that a wire or ribbon is cast. The melt may be forced by a mechanical ram, the head of melt in the crucible or the introduction into the crucible 11 of gas such as Ar or He. A chamber surrounds the apparatus and is evacuated for the melting. A starter wire or ribbon 20a is inserted in the die 15 and in a bore in a die part 13 of the graphite crucible. The portion 13 may be a separate piece of anisotropic pyrolytic graphite and replaceable. The crucible 11 and die part 13 are heated by an inductor coil 70 and the part B around the part 13 is separately controlled according to the temperature monitored by a thermocouple in the portion. Another thermocouple in the crucible detects the melt temperature coil. The Ti and Ni &c. are melted, alloyed and cast, before placing in the crucible 11 for melting, or they are melted in the crucible or introduced as a molten charge. The precast may be of a shape to fit the crucible. To seal the bottom of the crucible before extruding, a skull of the alloy is allowed to solidify at the bottom of the crucible 11. It is melted by the coil part B before extrusion. To obtain light oxidation of the extruded product, it passes through air, oxygen or Ar or He (possibly mixed with oxygen) supplied to an aperture 63 in a pressure plate 62. The crucible 11 is held between the plate 62 and an upper plate 60 by springs 61. Drawing.-The solidified wire or ribbon (20) from the continuous extrusion is drawn through a succession of dies (41-45) and annealed between passes, e.g. by furnace heating in air, electric heating by slide contacts, induction heating, oxy-acetylene torch or immersion in a bath of Woods metal or fused salt, with a final annealing before storage. The area reduction for each pass is 10-20% and annealing is at temperatures below 800‹ C. Oxide is removed from the wire or ribbon by abrasion or acid bath; to render it non-magnetic it is pickled in the acid after drawing or annealed in Ar or He.