STUDY ON DAMAGE EVOLUTIONG OF Cu-Ni19 ALLOY AT DIFFERENT ANNEALING TEMPERATURES BASED ON DIC METHOD

Using MTS-Landmark material testing machine and LEICA-LM/DM optical properties microscope, combined with digital image correlation (DIC) method, the tensile mechanical properties and the microstructures of Cu-Ni19 alloy under different annealing temperatures were analyzed. The damage evolution behaviors of different deformation zones under different annealing temperatures were analyzed. The results show that the yield strength and the tensile strength of Cu-Ni19 alloy decrease with the increase of the annealing temperature. Moreover, the recovery and recrystallization occur in the microstructure and tend to be equiaxed. The damage evolution of the Cu-Ni19 alloy can be divided into uniform deformation stage and local deformation stage. Also, the deformation zone of the sample is divided into large deformation zone and small deformation zone according to the deformation characteristics. In small deformation zone, the sample is mainly in uniform deformation and the deformation degree of grain increases slightly. In large deformation zone, the sample is mainly in rapid deformation and the deformation degree of grain increases significantly. Moreover, the deformation of small deformation zone has stopped basically. In both deformation zones, the damage factor increases with the increase of the strain, the damage deformation rate and the critical damage factor decrease with the increase of the annealing temperature. The damage evolution equation of Cu-Ni19 sample based on DIC method in both deformation zones under different annealing temperatures can reflect the law of damage evolution for Cu-Ni19 in both deformation zones effectively.