Constitutive Relationship Research Of AZ31 Magnesium Alloy Sheet Under The HVF & Warm Forming Condition

The constitutive relations of materials, especially dynamic plastic constitutive relations, have always been one of the emphases in mechanical and material fields. As the lightest metal, magnesium is attracting more and more interests, and widely used in the aviation, automotive and electrical industries. With the development of computer and the method of numerical calculation, numerical simulation has become an important measure in studying engineering,while dynamic constitutive relations of materials is still an obstacle astricting its development. But from the current literatures, we can see that the constitutive equations of magnesium alloy many scholars have established are almost about the qualitative analysis research of its stress and strain under hot compression deformation, which can not be used to depict the relationship of its stress, strain, strain rate and temperature under the hot tensile deformation. So for tensile deformation, the constitutive relation models mentioned in the literatures are insufficient, quote which will cite big error inevitably. The purpose of this study is to build a accurate constitutive relationship model of AZ31 magnesium alloy uhder the hot tensile deformation with high strain rate.Firstly, this paper introduces the research progress of AZ31 magnesium alloy under warm and high speed forming. Secondly, it gives an outline of constitutive relations of materials. Material stress in the phases of plastic distortion is not only related with strain, but also affected by loading history and strain rate,as well as temperature, especially introduces the impact of the strain rate and temperature on the material forming properties, lists several common constitutive equations used for AZ31 magnesium alloy.In order to build the constitutive equation of AZ31 magnesium alloy under the HVF&Warm forming condition, using the method of dynamic tension testing, the writer gets the stress-strain curves under the condition of forming with different strain rates and temperatures, analyse the influence of strain rate and temperature on material forming performance, from which we can get the following conclusions:1) when the strain rate is unchanged, the peak stress of AZ31 magnesium alloy decreases when the temperature increases, but elongation increases with the rise of temperature; 2) when the strain rate is unchanged, the peak stress of AZ31 magnesium alloy increases when the strain rate increases; 3) with the increase of strain, the yield strength of AZ31 magnesium alloy increase, and after rapidly reaching to the peak, when the flow stress slowly rises to a certain value, it starts to decline.According to the experimental data and stress-strain curves, through the model selection and numerical calculation, the writer of this paper builds the constitutive equation of AZ31 Magnesium alloy under the HVF&Warm forming condition. Finally, we verify the the accuracy of the constitutive equation according to the experimental data and the numerical simulation results. It shows that, the constitutive equation been built can well simulate the deformation process of material, and has certain theoretical significance.