US1710846A - Refinement of nickel alloys - Google Patents

Description

Patented Apr. 30, 1929. p

, 1,710,846 UNITED STATES PATENT. OFFICE.

WILLOUGHBY sm'raan sm'rn, or remnants, HENRY Josnrn GARRETT, or

LYNNE, AND JOHN ANGEL HOLDEN, 0F SUNNYSIDE, ENGLAND.

anrmmnnr or NICKEL ALLpYs.

No Drawing. Application filed May 3, 1928, Serial No. 274,959, and iii Great Britaip April 25, 1927.

difficult to work' when they contain even a small percentage of sulphur;'amounts of as little as 03% in certain alloys are very injurious.

If pure virgin metals are melted into alloys in furnaces in which there isno contamination and the alloys are subsequently worked by ordinary commercial processes, contamination by sulphur is almost inevitable. Such operations as preheating for rolling or for forgingiin gas or coal fired furnaces lead to an absorption of sulphur, which is necessarily confined to the surface of the material. When the rolled or forged scrap is returned to the furnace for melting, a small increment of sulphur is made to the charge. During the course of time thisinorement becomes greater, till eventually the material contains so much impurity that it cannot be worked as perfectl'y as the pure alloy.

According to this invention the charge consisting for example, of virgin metal with scrap or entirely of scrap is melted in the presence of a slag-and hydrogen or other reducing atmosphere. A suitable slag consists mainly of lime with silica, and a small amount of either fluo'rspar or calcium chloride may be used. Preferably the furnace is of the, induction type, using low, medium or high frequency.

It has been found that fifteen minutes refining with a slag of the composition mentioned, in an atmosphere as described, will reduce the sulphur content'very considerably in an alloy containing of nickel. The hydrogen supply is then cut off and the slag removed from the surface of the metal, and

our invention We have slgned our-names this before a new slag is formed, a small amount 7 of an oxide of one of the constituents of the oxide of ironFe O or Fe O, -may be infurnace few minutes and then a new slag is formed from suitable materials, etc. ing.

It is possible however after removal of the hydrogen directly to teem the metal from such as broken glass, The molten metal is then ready. for pourthe crucible but if so it will be found that during freezing a large volume of hydrogenis evolved and in consequence the resulting ingots are honeycombed. 7 Even with the use of de-gasifying agents, such as manganese, magnesium, silicon and the like, the resulting bars are worthless. They can, nowevor, be remelted in .the ordinary way and made into sound workable ingots (becausethe hydrogen is expelled during freezing), but this is not so economical as the method described above.

Additions of a suitable finishing agent such asmagnesium are made in the usual manner.

Whatwe claim is i 1. A method for the refinement by minimizing the sulphur content of nickel alloys having a nickel content of 50% or more, which consists in melting the furnace charge in the presence of a slag and an atmosphere of hydrogen, and subsequently after removal of the reducing atmosphere adding an oxide of one of theconstituent metals to absorb the absorbed hydrogen. 2. 'A method for the refinement by minimizing the sulphur content of nickel alloys having a nickel content of 50% or more, which consists in melting the furnace charge in the presence of a slag and hydrogen, cutting off the supply of hydrogen after about fifteen minutes and. then adding a small amount of an oxide of one of the constituents of the alloy for removing the absorbed hydroen. b In testimony that we claim the foregoing as 18th 'day of April, 1928. WILLOUGHBY STATHAM SMITH. HENRY JOSEPH GARNETT. JOHN ANGEL HOLDEN.-

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