LEAD-FREE FREE-CUTTING SILICON BRASS ALLOY WITH HIGH ZINC AND ITS MANUFACTURING METHOD

The present invention provides a lead-free free-cutting magnesium brass alloy which comprises 35.0 to 42.0wt% Zn, 0.1 to 1.5wt% Si, 0.03 to 0.4wt% AI, 0.01 to 0.36wt% P, 0.001 to 0.05wt% Rare Earth Elements, 0.05 to 0.5wt% Sn and or 0.05 to 0.2wt% Ni, optionally comprising 0.01 to 0.1wt% Ti, optionally comprising 0.05 to 0.4wt% Mg, and the balance being Cu and unavoidable impurities. The invented alloy is excellent in castability, weldability, cuttability, electroplating properties, corrosion resistance, mechanical properties, and is especially applicable in castings which need cutting and welding under low pressure die casting, such as castings for faucet bodies in the water supply system and also applicable in spare parts for ingots molding. The manufacturing method of the invented is easy to be operated. It's an environmentally-friendly new-type casting brass alloy.