磷钙无铅黄铜及其切削变形机理

摘要

为取代铅,减轻对环境的污染,采用磷和钙共同替代铅,获得了综合性能优良的磷钙无铅黄铜铸锭.为研究磷钙无铅黄铜的切削变形机理,采用卧式车床进行了切削实验,通过扫描电镜及能谱仪对切屑组织进行研究,并结合Griffith脆性断裂理论和切削力学计算,对切屑变形过程进行了分析.结果表明：磷钙无铅黄铜切削性能优良,切屑的尺寸和形貌与HPb59-1相当;沿晶界弥散分布的金属间化合物,割断了基体组织的连续性,切削时在剪切力的作用下,金属间化合物颗粒经变形后发生断裂或脱落,甚至在切削热的作用下部分熔化,引发基体产生应力集中,萌生裂纹并致使扩展,导致刀具前面剪切区剪切带的周期形成,并向自由表面扩展成层片结构,造成切屑断裂,从而提高了磷钙无铅黄铜的切削性能;磷钙无铅黄铜的综合性能优良,其替代含铅黄铜,具有可行性.%A novel lead-free brass containing P and Ca instead of Pb,whose over-all properties were excellent,was prepared by casting.Its cutting deformation mechanism was investigated by lathe turning experiment,and the cutting deformation was studied by scanning electron microscope（SEM） and energy dispersive spectrometer（EDS） in combination with Griffith theory of brittle fracture and cutting mechanics calculation.Results show that the cutting performance of P-Ca brass is good,the size and appearance of chips are the same as those of HPb59-1.Intermetallics distributed in grain boundaries cut off the continuity of matrix,during cutting,it fractures or falls off after deformation,even some melt because of the cutting heat,which cause sress concentration of matrix,lead to crack initiating and expensing,then the periodic shear bands slip to the free surface of chips into lamella structure,resulting in the fracture of chips and improving the cutting property.The properties of P-Ca brass is excellent,it is feasible to develop a new lead-free free-cutting brass containing P and Ca.