Aluminium alloys was used in the automotive parts industry increased for compensate steel parts material due to its lightweight and good surface. Since aluminium alloys are there relatively low mechanical properties although they can be deformed easily but the major limitation is their low formability. Especially the less bending radius which is often bending surface damaged easily. In the present work five-difference ratio of sheet thickness and bending radius for study to the bendability of cold rolled aluminum alloys AA6016 at low bending radius. The bending test by Air-bending method according to ISO 7438: 2010. To compare the results every 15 degrees. The mechanical behaviour surface roughness microstructure and damage evolution in the fillet region were analysed by experimental research. The experiment clearly showed that the Spring-back angle and bendability tend to decrease as the bending angle and material thickness increase. Due to the high tensile stress on the bending surface it effected to the surface roughness increases rapidly and led to the damage on the specimen bending surface. The initial cracks occur on the middle of the outer surface curvature and propagation in the shear plane pattern to the middle of the sheet thickness along the grain boundary. This is the consequence of plastic deformation by bending test.

Springback behavior is a major problem of sheet metal forming process. Especially aluminum alloy which often encounter such problems often. At present aluminum alloy is increasingly of used in the automotive industry for replace of the steels due to its lightweight and good finished surface. This work aims study to springback behavior of cold rolled aluminum alloy (AA6016) during air-bending process by ISO7438/2010 test standard. To analyze the influence of bending process parameter are included: sheet thickness punch radius bending angle die open and the ratio of bending radius and material thickness (r/t) effecting to springback behavior. The results are clearly that the springback angle is likely to increase with increase of the punch radius size of die open and the ratio of punch radius and sheet thickness and the springback tenor to decrease when the sheets thickness and bending angle increased. The increased bending angle will resulted to bending surface region is roughness increase and crack occurred to follow. As a result the bending force and the springback angle decreased.