Research On Microstructure And Mechanical Properties And Grain Size Effect Of Pure Copper

Copper has a very important role in industry for its many excellent characteristics such as low resistance, stable chemical performance at room temperature, low melting point, easy to re-smelting, easy to be recycled corrosion resistance, good plasticity and ductility. Copper strength and plasticity varies by changing in grain size. So the study of changing grain size on the mechanical properties is significant.Through different processes of annealing experiments,the process of recrystallization annealing microstructure, grain size distribution, grain orientation distribution, evolution of texture, and JMAK equation recrystallization kinetics were studied. Samples for tensile deformation rate change mechanical properties of pure copper. And explores after changing the grain size, how the strain rate sensitivity index change. Testing the microstructure of the samples drawn for getting grain size distribution, grain orientation distribution, evolution of texture of microstructure deformation zone, uniform deformation zone and necking zone.In the same annealing temperature, at the beginning, the microstructure performance equiaxed grains and deformed grains. With the time increased, deformed grains start to slowly recrystallization until fully recrystallized. Low angle grain boundary slowly being replaced by new large angle grain boundary formation. shear texture gradually disappear, replaced by axes grains to form the most stable cube texture. By JAMK hardness model calculates recrystallization activation energy value of Q=91.8KJ/mol.When the deformation rate increased, yield strength, tensile strength and yield ratio are increased by the grain size changed among 500nm,3μm,6μm,12μm and 90μm. Uniform elongation is rapidly increasing at first, when saturation occurs to 12μm. With the increase of grain size, strain rate sensitivity index m decrease. The value of maximum m is 0.023 when grain size is 500nm.By stretching process, equiaxed grain in non-deformed area boundary bend. As the process of stretching, the number of small-angle grain boundaries inside the grain increases rapidly. And coarse grain deformation after the organization has more small-angle grain boundaries. The original texture gradual conversion to fibrous texture after deformation.