Hot compression experiment for the liquidus casting ZK60 alloy is conducted at temperature ranging from 200 to 360deg C and strain rate from 10~(-3)to 1 s~(-1).The flow stress-true strain curves show that the flow stress reaches a peak and then keeps a steady value at temperatures from 240 to 360deg C.The peak stress decreases along with rising temperature and decreasing strain rate.A constitutive model is developed to describe flow stress as a function of temperature,strain rate,strain and strain softening coefficient.Then the bar extrusion experiments at elevated temperatures are performed.The extrusion processes are simulated by introducing proposed constitutive model into finite element method,and the distribution of temperature,effective stress and plastic strain are analyzed.Stress is relatively high around the entrance of the conical die,whereas the maximum temperature and strain appear near the exit of conical die.Finally,the yield strength,tensile strength and elongation of practically extruded bar are measured.
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