成形过程对ZK60镁合金薄带组织和力学性能的影响

用OM,SEM,TEM和电子万能试验机对不同方法制备的ZK60镁合金薄带的组织和力学性能进行了研究.常规铸造ZK60镁合金轧制后仍为等轴晶组织,晶粒尺寸明显细化,双辊铸轧ZK60镁合金条带温轧变形后,显微组织由树枝晶转变为纤维状变形组织,且有高密度剪切带产生,温轧过程中没有明显的动态再结晶发生.轧制后两种合金均具有良好的力学性能,轧制态铸轧合金的强度明显高于传统铸造合金,伸长率略低于传统铸造合金.退火热处理后两种合金均发生了再结晶,得到等轴晶组织,且铸轧合金的组织比传统铸造合金的组织更加均匀细小.退火热处理使薄带的强度略有下降,而伸长率大幅度提高,退火后双辊铸轧合金和传统铸造合金的抗拉强度、屈服强度和延伸率分别为:388 MPa,301 MPa,22.9％和311MPa,219 MPa,19.3％.镁合金薄带制备过程的晶粒细化归因于剪切带、位错和挛晶的产生及后续退火过程中再结晶.

Effect of Forming Process on Microstructure and Mechanical Properties of ZK60 Alloy Sheet

The microstructure and mechanical properties of ZK60 alloy sheet produced by different method were investigated using OM,SEM,TEM and a standard universal testing machine.The results show that,for conventional casting (CC) alloy,the equiaxed structure is refined after warm rolling.But for twin roll casting alloy,the microstructure changes from dendrite to fibrous deformed structure after warm rolling.Relatively higher density of shear bands can be observable in TRC ZK60 alloy sheet and no obvious dynamic recrystallization has been found after warm rolling.After warm rolling,the two alloys possess good mechanical properties,and the strength of TRC alloy is much higher than that of CC alloy,and elongation of TRC alloy is a little lower than that of CC alloy.The annealing heat treatment after warm rolling will induce a little decrease of strength and great increase of elongation of the two alloys.The tensile strength,yield strength and elongation of TRC and CC alloy sheet are 388 MPa,301 MPa,22.9％,and 311 MPa,219 MPa,19.3％,respectively.The grain refinement during manufacturing processes is attributed to the formation of heavy shear bands,high density dislocation,twins,and the recrystallization during subsequent annealing process.