Lead-free free-cutting phosphorus brass alloy and its manufacturing method

Considering the solid solubility of P in the matrix of copper will be decreased rapidly with the temperature decrease and form the brittle intermetallic compounds Cu 3 P with Cu, the present invention elects P as one of the main elements for ensuring the excellent cuttability of the invented alloy. The lead-free free-cutting phosphorous brass alloy comprises: Cu, Zn, 0.4 to 1.6wt% P, and other elements in the amount of 0.005 to 0.6wt%, which comprise at least two elments selected from the group consisting of Al, Si, Sb, Sn, Re, Ti and B, and the balance being unavoidable impurities. The phosphorous brass alloy contains a combined wt% of Cu and Zn of between 97.0wt% and 99.5wt%, within which the content of Zn is above 35wt%. The method of manufacturing the alloy is also disclosed. The invented alloy has excellent cuttability, castability, hot and cold workability, dezincification corrosion resistance, mechanical properties and weldability. The phosphorous brass alloy is applicable in spare parts, forging and castings that require cutting, and particularly in forging and castings for low pressure die casting that requires cutting, grinding, welding and electroplating. The phosphorous brass alloy may be used for faucets, valves and bushings of water supply systems, and for bar and wire materials that require high corrosion resistance and compactness.