Tin-free lead-free free-cutting magnesium brass alloy and its manufacturing method

A tin-free lead-free free-cutting magnesium brass alloy comprises 56.0 to 64.0 wt.%Cu, 1.05 to about 2.1wt.% Mg, 0.21 to 0.4wt.%P and other elements 0.002 to 0.9wt% which comprise at least two elements selected from the group consisting of Al, Si, Sb, rare earth elements, Ti and B and the balance being Zn with unavoidable impurities, wherein a cutting percentage of the alloy is at least 80%. The process for producing such a alloy is also proposed. The invented alloy is excellent in cuttability, castability, hot and cold workability, corrosion resistance, mechanical properties and weldability and particularly applicable in spare parts, forging and casting which need cutting and grinding process. The cost of necessary metal materials of the invented alloy is lower than lead-free free-cutting bismuth and antimony brass alloy and is equivalent to lead-contained brass alloy.