| Rare earth magnesium alloy has high strength and excellent high temperature stability,corrosion resistance and high temperature creep resistance,solving the traditional magnesium alloy materials are widely used in aerospace,weapons and transportation and other fields have a broad application prospects.However,due to its significantly lower forming properties than the traditional commercial AZ magnesium alloy,the rolling of rareearth magnesium alloy plate is more difficult,which seriously restricts the batch production and application of rare-earth magnesium alloy plate,and it is urgent to improve and optimize the rolling process.Therefore,this paper takes Mg-13Gd-4Y-2Zn-0.5Zr in extruded state as the research object,and carries out hot rolling experiments and electric pulse rolling experiments under different rolling process parameters to study the influence of different rolling process parameters on the organization and properties of this alloy in order to develop a reasonable rolling process,to investigate the influence of different current parameters on its organization and properties,to reveal the feasibility of using pulse current to improve the rolling properties of this alloy and The feasibility of using pulsed currents to improve the rolling properties and optimize the crystallographic structure of the alloy and the underlying mechanisms were investigated.Firstly,the thermal compression experiments were carried out by Gleeble-3800 thermal simulation tester to investigate the thermal deformation behavior of Mg-13Gd-4Y-2Zn-0.5Zr magnesium alloy.It is shown that the rheological stress decreases with increasing deformation temperature and increases with increasing strain rate.Based on the rheological stress data,the thermal processing diagram of this alloy was drawn,and its hot rolling temperature interval was initially clarified to be 360～480°C.Secondly,hot-rolling experiments with different rolling process parameters were carried out at 10% deformation in a single pass using homogenized "reciprocal upsetting and squeezing" Mg-13Gd-4Y-2Zn-0.5Zr plate as raw material to analyze the effects of rolling process parameters on the microstructure and mechanical properties of the alloy.The grain size decreased significantly with the increase of deformation,the plate weave tended to be obvious,the tensile strength increased with the increase of deformation,the elongation decreased with the increase of deformation;the tensile strength reached the maximum tensile strength at 400 ℃,the elongation increased with the increase of temperature;with the increase of rolling speed,the tensile strength and elongation both increased with the increase of rolling speed.The mechanical properties of the rolled plates were improved to different degrees compared with the initial plates,and the reasonable rolling process for Mg-13Gd-4Y-2Zn-0.5Zr plates was determined by combining three factors: deformation greater than 30%,temperature around 400°C,and rolling speed greater than 0.12m/s.Finally,in order to investigate the feasibility of using pulsed current to improve the processing properties of Mg-13Gd-4Y-2Zn-0.5Zr and optimize its crystallographic structure,electric pulse-assisted hot rolling experiments of rare-earth magnesium alloy were carried out to systematically compare the differences in microstructure and properties of this alloy during the same working condition of warm rolling and in the electric pulse rolling process.The results show that the tensile strength increases with the increase of current intensity,increases with the increase of frequency and decreases with the increase of pulse width,and the high-energy pulse current can improve the plasticity of the material and increase the elongation of the material without significantly decreasing the tensile strength compared with the hot-rolled state organization.The experimental results can provide a reference for the optimization of the electroplasticity processing process of magnesium alloy. |
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