Preparation, Structure And Properties Of Low-Copper Lead-free Silicon Brass

Lead brass has excellent mechanicial properties and cutting performance，it has beenwidely used in the field of electronic telecommunications，household electical appliances，drinking water projects，toys，automotives，mechinery and instrument manufacturing.However, lead is an element of huge hazards to enviroment and human，so it will bringenormous social and ecnomic benefits to replace lead with non-toxic elements and to achivethe purpose of cutting at the same time.Silicon as alternative element to substitute part of lead in the lead brass，while still toretain appropriate level of lead and to add some amount of other elements such as iron，tin，phosphorus and manganese to form a comprehensive effect in the alloy, which makes thealloy can not only meet the requirements of Lead-free Act but also still has acceptable cuttingperformance and cost-competitive advantage. Orthogonal experiment is used to optimize thealloy composition ratio of the major alloying elements copper，lead and silicon. The lowcopper lead-free low silicon brass was prepared successfully. The tensile strength，dezincification corrosion and cutting performance were measured, and the cutting mechanismwas prelimilary discussed. The conclusions are as follows:（1）For Low-copper alloy containing61%-65%copper, the copper content is the mainfactor affecting the tensile strength, and other ingredients has no significant effect on thetensile strength.（2）Asmall amount of lead added in the alloy is dispersed in the form of granular lead,which play the role of chip breaking and lubrication in machining. Even if the alloy containsonly small amounts of lead, which still plays an effective help to the improvement of alloycutting performance. Therefore, in the study of lead-free copper alloy, adding a small amountof lead, but below the limit of its content is still allowed by the lead-free bill, which will notimpact on the environment and human health but can improve the cutting performance.（3）Silicon is added in copper alloy, the γ phase will be formed in the alloy. The smallγ-phase in the brass can play the role of the broken chip, and its cutting performance is similarto lead brass. However, due to the hard and brittle γ-phase, excessive γ will reduce theductility of the alloy, so the cutting performance will be reduced. The experimental resultsshow that the copper content is63%, the appropriate dosage of silicon is about1.0%. (4) The low copper lead-free brass developed in this study has tensile strength of468MPa，yield strength of168MPa，percentage elongation of42%，dezincfication depth of93um. The chip is brief，small and broken. The sample’s surface smoothness is relativelyhigh after machining. The overall cutting performance of this alloy is acceptable. It canreplace lead brass and has cost advantage.