Bending in aluminium alloys AA 6111 and AA 5754 using the cantilever bend test

Abstract

Bendability is an important forming parameter in many applications, but particularly in automotive parts where the formed parts in structures can be quite complex, and where outer skins are joined to inner panels through the hemming process. In this paper the bend performance of two aluminium based automotive alloys, the heat treatable skin alloy, AA 6111 and the non-heat treatable structural alloy AA 5754, are assessed by the cantilever bend test. This test enables the load ± bend angle relationship to be monitored, and provides a bend surface that can be examined for different bend angles, since the bending pin does not contact the specimen surface in the local region of the bend. The results demonstrate that the cantilever bend test can differentiate between different bend performance, and the differences relate to the damage process involved in bending. In the heat treatable AA 6111 the bendability is dependent on the alloy temper, which controls the bend angle at which large surface cracks appear on the surface. This fracture process is a result of differences in the development of surface topography and surface damage with bending strain. The AA 5754 alloy has similar behaviour, but the performance is superior to the best of the AA 6111 tempers, and re¯ects a lower rate of surface topography development, and an absence of signi® cant surface cracking over the bend angle range investigated.MST/5130

The Deformation of Clad Aluminum Sheet Produced By Direct Chill Casting

“…For materials in which the neutral axis remains at the center of the sheet, such as materials with limited ductility, they derived C = 50, whereas for a moving neutral axis, they suggested C = 60. Previous results [10,12] on bending in Al alloys have shown general agreement with Eq. [5], but with a C value of about 70.…”

“…Bending in monolithic Al alloys is still not well understood, but recent publications [10][11][12] have shown that the surface develops severe topographical features both in the matrix, where strain localization in severe bands develops, and at grain boundaries. In addition, cracking is initiated in these regions.…”

“…The wrap bend result is influenced by the sheet surface condition, and in the present experiments, the processed mill finish to the sheet was used. A second test also was used to obtain bending load-bend angle information, which can be obtained from the Cantilever bend test [9,10] (CBT). The bendability also varies with the bend axis orientation in the sheet; unless noted, the bendability was assessed in the transverse orientation, which means that the bend axis is parallel to the rolling direction.…”

An experimental and numerical study of prestrained AA5754 sheet in bending

“…Localized bending may also occur as wrinkling, which is a failure mode often seen in sheet forming and in the compressive zone during tube bending where local buckling or bending instability occurs. In many cases, bending occurs in the later forming stages, where the existing residual strains can cause accelerated strain localization and reduce bendability as shown by Sarkar et al (2001) and Lloyd et al (2002). Bending of AA5754 sheet has been performed and simulated using techniques such wrap bending (Hu et al, 2010) and V-bending (Toros et al, 2011), both of which produce inhomogeneous deformation due to the interaction with the loading tool.…”

Mechanical Properties of Aa5754 Sheets Welded by Cold Metal Transfer Method

“…Leo et al (2016)reported that, fast cooling rates cause the solute atoms may be trapped in Al matrix without precipitating particles. Bending is an important forming property particularly in automotive applications [17]. Bending test results are given in Figure 5.…”