Microstructures and properties of reciprocating extruded as-cast ZK60 magnesium alloy

As-cast d 50 mm ZK60 magnesium alloys were reciprocating extruded for different passes under(335±5)℃. The microstructures and properties of the alloys were studied under different reciprocating extrusion passes. The results show that,reciprocating extruded microstructures were refined and uniformed effectively,in compared with as-cast condition. For 2 passes,the grain size is about 7 μm. After 4 passes,the grain size is about 6 μm. During reciprocating extrusion,refined as-cast eutectic and reinforcement phases in dispersed particles are uniformly distributed on matrix,and their size is less than 50 nm. The tensile strength,yield strength and the elongation of 4 passes reciprocating extruded as-cast ZK60 magnesium alloy are 311 MPa,214 MPa and 17.93%,respectively. The thermal expansion coefficient of RE-4-EX-ZK60-CT magnesium alloy is the lowest. More or less extrusion passes can not decrease the value of the thermal expansion coefficient.