Heat treatment method
AssigneeBOC Limited
InventorsRobert G. Bowes, Robert D. Chapman
Life of this patent
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Abstract
In order to decarburize ferrous metal without recourse to an exothermic generator, an inert gas (typically nitrogen), water and a liquid or vaporous compound of carbon, hydrogen and oxygen (typically methanol) are admitted to a working chamber of the heat treatment furnace in which the metal is situated. The decarburization is preferably performed at 700.degree. to 800.degree. C. The methanol and water react to form a non-oxidizing, decarburizing atmosphere at the decarburizing temperature. The metal may be oxidized at a temperature below 600.degree. C. in another chamber of the furnace, the atmosphere from the decarburizing chamber being passed into the oxidizing chamber.
Claims10
A method of decarburising ferrous metal comprising the steps of introducing the ferrous metal to be decarburised into a working chamber of a heat treatment furnace, raising the ferrous metal to a temperature at which decarburisation is able to take place, and establishing in the working chamber a decarburising atmosphere by admitting into the chamber inert gas, water and a compound of carbon, hydrogen and oxygen, the relative proportions of water and the compound of carbon, hydrogen and oxygen being such that at the prevailing temperature in the working chamber the atmosphere established therein contains at least about 1% water vapor and decarburises the ferrous metal without forming oxide of the ferrous metal.
A method of decarburising ferrous metal comprising the steps of introducing said ferrous metal into a working chamber of a heat treatment furnace;
- heating the working chamber to a temperature between 600.degree.-1120.degree. C.;
- introducing nitrogen, water and a compound of carbon, oxygen and hydrogen into a working chamber to form therein a decarburising atmosphere comprised of approximately by volume 3-8% carbon monoxide, 2-6% carbon dioxide, 6-16% hydrogen, 1-5% water vapour, balance nitrogen;
- and retaining said ferrous metal in said working chamber for a time sufficient to decarburise said ferrous metal without forming oxide of said ferrous metal.
Dependencies are inferred from the claim text.