触变挤压铜合金力学性能研究

Mechanical Properties of Thixo-extruded Copper Alloy

摘要:

采用触变挤压工艺成形ZCuSn10P1铜合金轴套零件,通过单向拉伸实验和硬度实验研究了触变挤压铜合金的抗拉强度、延伸率、布氏硬度和显微硬度,利用扫描电镜观测了断口形貌并分析了断裂方式,分析了成形比压对触变挤压铜合金力学性能的影响规律。结果表明,抗拉强度随成形比压增加而先增加后降低。延伸率随成形比压增加而不断减小。成形比压与抗拉强度和延伸率的函数关系分别为抛物线和幂指数。触变挤压铜合金拉伸断裂方式为沿晶断裂和韧性断裂的混合型断裂。布氏硬度随成形比压增加而先增加后降低。相同工艺条件时,液相显微硬度值最高,固液界面次之,固相最低。固相、固液界面和液相的显微硬度均随成形比压增加而先增加后降低。触变挤压铜合金综合力学性能要高于常规铸造,较佳工艺参数为成形比压250 MPa、挤压速率15 mm/s,其抗拉强度、延伸率和布氏硬度分别为387 MPa、2.8%、128 HBW。

Abstract:

ZCuSn10P1 copper alloy was formed by using thixo-extrude process. The mechanical properties with tensile strength, elongation, Brinell hardness and Vickers hardness were measured by using uniaxial tensile test and hardness test. The fracture morphology was observed by scanning electron microscope and the fracture mode was analyzed. The influence of forming specific pressure on the mechanical properties of thixo-extruded copper alloy was investigated. The tensile strength increases first and then decreases with increasing forming specific pressure. While the elongation decreases with increasing forming specific pressure. The functional relationships between forming specific pressure and the tensile strength and elongation are parabolic and exponential, respectively. The tensile fracture mode of thixo-extruded copper alloy is hybrid fracture including intergranular fracture and ductile fracture. The variation of Brinell hardness increases first and then decreases with increasing forming specific pressure. The Vickers hardness of liquid is highest, followed by the solid-liquid interface, the lowest solid phase at the same process. The microhardness of the solid phase, the solid-liquid interface and the liquid phase both increases first and then decreases as the forming specific pressure increases. The mechanical properties of thixo-extruded copper alloy are higher than that of conventional casting. The process parameter at forming specific pressure of 250 MPa and extrusion rate of 15 mm/s is fine. And the tensile strength is 387 MPa, the elongation is 2.8%, the Brinell hardness is 128 HBW, respectively.