GB445620A - Improvements in and relating to copper-tin alloys - Google Patents

Abstract

A bronze which can be subjected to hot working processes comprises copper, 3-10 per cent of tin, 0,2-4 per cent of iron or cobalt, and 0,5-10 per cent of chromium or 0,2-1 per cent of vanadium, or both chromium and vanadium in the proportions specified. Nickel, manganese, and aluminium may be added in amounts not exceeding 4 per cent of each element. Bronzes particularly suitable for the casting of bearing parts subject to heavy loads or high temperatures preferably contain 5-10 per cent of tin, 3-10 per cent of chromium, and 0,2-4 per cent of iron or cobalt. The alloys are preferably made by melting down commercial copper-tin alloy ingots, adding sufficient copper to bring the tin content to the required value, and covering the molten metal with a flux which is preferably a mixture of sodium and calcium fluorides with or without other fluorides, but which may be fused boric acid, borax, or mixtures of borax with glass. Magnesium or phosphorus, e.g. in the form of phosphor copper, is added to deoxidize the melt and lumps of metallic chromium together with metallic iron or cobalt, or lumps of ferrochromium, ferro-vanadium, or ferro-chromevanadium are then dropped through the flux, the temperature being raised to about 1250 DEG C. Dry sand is then added to the flux to form a pasty mass and the metal is cast. When casting in permanent moulds, 0,2 per cent of aluminium is preferably included in the alloy. The Specification as open to inspection under Sect. 91 describes alloys consisting of copper 3-10 per cent of tin, and either or both of 0,5-10 per cent of chromium and 0,2-1 per cent of vanadium. This subject-matter does not appear in the Specification as accepted.