Research On Constitutive Equation And Rolling Properties Of B₄C/Al Composites

As an excellent performance aluminum matrix composites,B₄C/Al composites have a lot of advantages like high specific modulus,high specific strength,abrasion resistance,corrosion resistance,good dimensional stability,low coefficient of thermal expansion.These advantages make B₄C/Al composites had great application prospects in aerospace and other fields.Due to the addition of B₄C particles,it brings difficulties to hot deformation of aluminum alloy.Therefore,the study of the thermal deformation behavior and rolling properties of B₄C/Al composites has important theoretical significance and application value.In this paper,isothermal compression tests are performed by using the Gleeble-3800 thermal simulator.The influence of the temperature fluctuation on the experimental results was analyzed and corrected.The hot deformation behavior of B₄C/6061Al composites is investigated,and the effect of temperature and strain rate on the flow stress is analyzed.Based on the dynamic material model,the hot processing maps of B₄C/6061Al composites are established,and the effect of different deformation conditions on the microstructure evolution of the composites was analyzed by metallographic observation.Hot rolling process is simulated by DEFORM software.The rolling properties of B₄C/6061Al composites and the influence of different process parameters on the temperature field,deformation field,edge damage and rolling force of rolled piece are analyzed.The main results of this paper are as follows:?1?When strain rate more than or equal to 1s^-1,temperature fluctuations have a greater impact on the experimental results.Steady-state flow characteristics of B₄C/6061Al composites are observed during hot deformation,and the flow stresses increase with the increasing strain rate and the decreasing temperature.Arrhenius-type can predict the hot deformation behavior of B₄C/6061Al composites well.?2?From the hot processing maps,we can see that the processing instability zone of B₄C/6061Al composites lies in the range of deformation temperature of 375?450?and strain rate of 2.23?10s^-1.The optimum processing area locates at the deformation temperature of 480?525?and the strain rate 0.01?0.04s^-1 range.Metallographic observation shows that increasing the temperature is conducive to promoting recrystallization nucleation,while increasing the strain rate will limit recrystallization and grain growth.?3?From the simulation results,the temperature field and the deformation field in the deformation area of the rolled piece are unevenly distributed;the rolling damage occurs only in the edge region;the rolling force fluctuates sharply during the bite and breakout of the rolled piece,and trend stabilized in the steady rolling stage.The influence of different process parameters on the hot rolling process is remarkable,in which the initial temperature of the rolled piece has a significant effect on the temperature,equivalent stress and rolling force of the rolled piece;the roll speed has a significant effect on the temperature and equivalent strain rate of the rolled piece;the rolling reduction has a significant effect on temperature,equivalent strain,equivalent strain rate,edge damage and rolling force of the rolled piece.