| As an aging precipitation strengthening alloy,Cu-Cr alloy is widely used in high-speed train contact lines,lead frames,aerospace and other fields due to its excellent mechanical properties and electrical conductivity.In this paper,Cu-Cr-Zr-Ti alloy ingots were prepared by atmospheric melting using pure copper（99.95 wt.%）,pure titanium（99.99 wt.%）and Cu-8wt.%Cr as raw materials.The true stress-true strain curve of the alloy was obtained on the machine through a single pass isothermal compression test.By analyzing the true stress-true strain curve,it is obtained that three Cu-Cr alloys are temperature and strain rate sensitive alloys.At the same time,the true stress-true strain curve is found to be severely hardened.A modified Arrhenius type is proposed.The equation describes the work hardening behavior of the alloy during hot deformation and the model was verified with Cu-Cr-Sn,Cu-Cr-Mg and other alloys.Through the true stress-true strain curve,the hot working diagram of Cu-Cr-Zr-Ti alloy is drawn,and the microstructure of different regions in the processing map is analyzed.The microstructure evolution of Cu-Cr-Zr-Ti alloy during hot deformation was obtained,and the optimum thermal deformation process parameters of Cu-Cr-Zr-Ti alloy were obtained.The effect of back stress on work hardening of alloy during hot deformation is studied.It is found that the increase of true stress during hot deformation is caused by the increase of back stress,and the back stress is related to strain.The strain is introduced into Arrhenius as an independent variable.In the equation,a modified Arrhenius-type constitutive model is obtained,which can well describe the rheological behavior of the alloy.The physical meaning of the parameterαvalue in the model was verified by transmission electron microscopy and X-ray diffraction.The corrected model was used to calculate the true stress value and compared with the experimental values of the three alloys.The correlation coefficients were all above 0.9.In addition,the accuracy of the model was verified by alloys of other systems（steel,titanium,magnesium）.In the verification of other metals,the correlation coefficients were all above 0.95.The hot-worked graph of the alloy was obtained by the true stress true strain curve of Cu-Cr-Zr-Ti alloy.The microstructure evolution of the alloy at high temperature was analyzed by thermal processing.The true stress of the alloy increases with the increase of strain rate during hot deformation and decreases with the increase of temperature.The microstructure of the high temperature compression experiment was observed,and the tissue evolution law was consistent with the prediction of the thermal processing map.The optimum thermal processing parameters of the alloy were obtained by a hot working diagram with true strains of 0.4 and 0.8:temperature 850°C-900°C,strain rate 0.01 s-1-0.1 s-1. |
