Strength improvement in ZK60 magnesium alloy induced by pre-deformation and heat treatment

Abstract

The influence of pre-deformation and heat treatment on mechanical properties of as-extruded ZK60 alloy was investigated. The experimental results indicated that the solid solution, pre-cold rolling and artificial aging treatments remarkably improved the mechanical strength of alloys compared with the as-extruded condition. Especially, pre-cold rolling in 5% reduction combined with artificial aging at 150 °C for 20 h was determined as the optimum heat treatment condition, which resulted in a yield strength of 333 MPa with an increment of 87 MPa and ultimate tensile strength of 373 MPa. High density of nanoscale precipitates in α-Mg matrix observed in this sample was beneficial to enhancing the strength. The as-extruded sample showed a typical brittle fracture while the solution treated sample exhibited ductile-fragile failure characterized by cleavage fractures, river patterns, and tear ridges. And the sample after pre-cold rolling combined with aging presented more equiaxial dimples with a great amount of cracked particles in them. The above-mentioned observations were analyzed in terms of microstructure and possible strengthening mechanism in the extruded ZK60 alloy.

Keywords

ZK60 alloy / strength / solid solution / pre-cold rolling / aging

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