二次挤压对挤压和ECAP变形后ZK60镁合金显微组织和力学性能的影响

摘要

The microstructures and properties of ZK60 alloy were evaluated under four different conditions: extrusion; extrusion and 4 passes of equal channel angular pressing (ECAP); extrusion,4 passes of ECAP and secondary extrusion; and extrusion,4 passes of ECAP,annealing and secondary extrusion.Secondary extrusion at ambient temperature was successfully processed to produce ultrafine-grained ZK60 alloy.The results show that ECAP introduces significant grain refinement and there is additional refinement in secondary extrusion.High yield strength of 342 MPa is achieved after secondary extrusion at room temperature,but the elongation to failure is only 0.8％.However,by applying annealing before secondary extrusion,the ductility of ZK60 could be greatly improved to 4.5％,meanwhile the yield strength almost remains the same,and the ultimate strength of up to 388 MPa is obtained.%测试四种状态下ZK60合金的显微组织和力学性能,四种状态分别为;挤压；挤压+4道次ECAP；挤压+4道次ECAP+二次挤压；挤压+4道次ECAP+退火+二次挤压.在室温下成功地进行ZK60的二次挤压,得到超细晶组织.结果表明:ECAP和二次挤压可以显著细化晶粒.挤压+4道次ECAP+二次挤压后的ZK60合金的屈服强度为342 MPa,但是其伸长率只有0.8％.在二次挤压之前进行退火,ZK60合金的伸长率可以提高到4.5％,而屈服强度基本不变,抗拉强度达到388 MPa.