Research On Warm Plastic Deformation And Impact Resistance Of ZK60Magnesium Alloy

In the near future, the quantities of magnesium alloy material will be much more than aluminum alloy to become the most widely used metal structure material in weapon equipment. Mg alloy has the highest strength, good plasticity and stain resistance to be one of the most used wrought Mg alloys.In this paper, plastic deformation properties, mechanical properties and thermal-shock resistance of ZK60alloy were systematically studied and then its value on armor protective aspect was evaluated in order to lay a theoretical foundation for its use, which could direct its engineering application in the military industry.The main research contents and conclusions are as follows:1. Gleeble thermal simulation analysis shows that the machinability of ZK60alloy is not so well as AZ80Mg alloy. And the thermal formability of ZK60alloy is good when the temperature is above300℃and the strain rates is1s-1.2. The results of hot compression experiment show that with Zr insoluble compounds existing, after homogenization, ZK60alloy not only eliminates its as-cast network structure, but also keeps grain refining effect, which would continue to later thermal deformation and heat treatment and make hot-worked ZK60alloy have good mechanical properties.3. Not only in hot compressed state and hot compressed+T5state but also in hot compressed+T6state, tensile strength of ZK60alloy all reach the peak with the strain rate of2.07. However the strain rate is different when elongation appears extremum.4. The influence of extrusion process parameters on microstructure and properties of ZK60alloy under large deformation is studied in forward extrusion+aging experiments. The results of forward extrusion show that when strain rate is larger (3.40,3.80), the mechanical properties reach a constant level. Later, with strain rate increasing gradually, the waste of die and energy could not be avoided and the properties decrease. 5. When deformation parameters (temperature, strain) are same, the average tensile strength of forward extrusion state ZK60alloy is78MPa more than hot compressed state ZK60alloy, and the average elongation of forward extrusion state ZK60alloy is4.2%less than hot compressed state ZK60alloy. Besides, forward extrusion+T5state ZK60alloy has better mechanical properties as well as the results of hot compressed+T5experiment.6. ZK60alloy is experimented with Hopkinson low velocity impact test (<100m/s). The results show that the larger is strain state, the more obvious is yield point and yield platform of dynamically true stress-strain curve. Besides, the fracture part is longer with the increasing of strain state, especially when the strain state is2600s-1.7. The impact process and failure characteristic of ZK60alloy under high speed impact by steel bullet have been studied. The main results are as follows:(1) Shear ship appears in the shot hole back of target plate. This states that ZK60alloy has better defensible performance.(2) The defensible performance of hot deformed+T5state ZK60alloy is better. The cracks hardly appear around the crater. The defensible performance of hot deformed+T6state ZK60alloy is less. The vertical cracks obviously appear around the crater. Some hot deformed Mg alloy has cracks. But some have not cracks and are smooth.(3) The relation between shear depth and mechanical properties of target plate material is established by linear regression equation:y=13.1-0.03x,(y=h; the less is value of y, the better is defensible performance of target plate material). The relation states that only when Rm, Rp0.2and A all could reach the most ideal state, the material can obtain excellent defensible performance.