Morphology observation for surface orange peel and fracture in tension sample of aluminum alloy sheet and characterization of nano hardness

The tension property of aluminum alloy sheet with different microstructures is measured, and the surface and tension fracture morphology of tension sample with and without orange peel are observed by using scanning electron microscope (SEM). Surface roughness and nano hardness of tension sample are measured. The results show that the average elongation of the samples with orange peel is lower than that without orange peel; especially the r value of perpendicular to the rolling direction is much lower than that without orange peel. The tension surface of the orange peel samples is very rough; various parameters of surface roughness are higher. Under the observation of SEM, a wider sliding band with a micro crack on the surface of orange peel sample can be found. The various parameters of surface roughness without orange peel sample are near to zero, the sliding band is narrow and without micro cracks. The dimple width in tensile fracture of orange peel sample is larger than that without orange peel sample, but shear lip is narrower. The nano hardness testing results show that samples with orange peel behave high elastic modulus, high hardness, and high maximum load, but low plastic deformation depth. These mentioned features can completely describe surface and fracture morphology of tension samples with orange peel.