.60 Of Cu-zn-xmg Alloy Performance Study

The application of copper and copper alloys is very extensive for excellent performance.Lead brass alloys are applied in various fields, such as household electrical appliances,electric telecommunications, potable water system,toys,automotives,mechanical manufactures and device manufactures,due to its excellent mechanical properties and cutting properties,but Pb is a kind of element harmful to environment and human being,so it will bring enormous social benefit and economic benefit to replace Pb using innocuous elements and reach its cutting properties.The purpose of this study is to develop a new kind of easy cutting leadless magnesium brass,which is to substitute for the widely used toxic leaded brass.In this work,the easy cutting magnesium brass was fabricated by melting,casting and extruding processes.The effect of adding Al and Bi on the microstructure and corrosive properties were studied by X-ray diffraction,optical microscope and scanning electron microscope.The mechanical property and machinability were tested by electron universal test machine and metal stock removing machine.The following results were obtained:1) The influence of Mg on melting point,phase transformation temperature and microstructure development of alloys were investigated.The results showed that,the addition of Mg decreased the melting point and phase transformation temperature ofα�'β,as well as leading to the precipitation of Cu₂Mg phase.2) The variation of microstructure and mechanical property of 60Cu-Zn-xMg alloys were studied,and the effect of Al and Bi were analyzed.Experimental results revealed:the best mechanical property of 60Cu-Zn-xMg alloy exist when the content of Mg is 1.6wt%.The addition of Bi decreased the plasticity of Mg-brass and the grain size of as-extruded 60Cu-Zn-2.4Mg-0.3Al alloy was smaller than others.The ultimate tensile strength of 60Cu-Zn-2.4Mg-0.3A1 was 543.39MPa. 3) The cutting properties of 60Cu-Zn-xMg improved while the content of Mg increased.The size of chips of 60Cu-Zn-2.4Mg-0.3Al became smaller and the cutting force decreased.The results also show the significant factors effecting cutting properties are in the order of depth of cut,feed rate and cutting speed.According to the fracture theory of Griffith,the critical dimension of Cu₂Mg was calculated,which is 0.70μm.4) The corrosion resistant properties of 60Cu-Zn-xMg decreased while the content of Mg increased.The addition of Al and Bi improved the corrosion resistant properties of 60Cu-Zn-xMg and the depth of dezincification of 60Cu-Zn-2.4Mg-0.3Al alloy was smallest.5) The comprehensive property of 60Cu-Zn-xMg alloy was excellent while the content of Mg was 2.4wt%.The tensile strength,yield strength elongation and hardness of magnesium are 494.39MPa, 388.56MPa,9.03%and 139.5HV respectively.The main-cutting-force is 350N,and the depth of dezincification of lateral and vertical is 863.8μm and 1213.8μm respectively6) By adding Al and Bi to the 60Cu-Zn-2.4Mg alloys,the comprehensive property of 60Cu-Zn-2.4Mg-0.3Al alloy was fine. The tensile strength,yield strength elongation and hardness of magnesium are 542.73MPa,375.24MPa,8.61%and 153HV respectively.The main-cutting-force is 1450N,and the depth of dezincification of lateral and vertical is 588.0μm and 643.8μm respectively.