Derin Ovalama İşlemi Sonrasında 6082 Alüminyum Alaşımı Üzerinde Oluşan Plastik Deformasyon ve Artık Gerilmelerin Sonlu Elemanlar Analizi ile İncelenmesi

Abstract

The purpose of this study is to investigate the directional dependency of residual stresses on different sample geometries occurred just after deep rolling using finite element analysis (FEA). One of the most effective way to increase the fatigue strength in the parts subjected to dynamic loading is to create compressive residual stresses on the part surface and at a certain depth of the material [1]. Deep rolling is the most effective process in terms of ability to produce compressive residual stresses [2]. During this process, a local plastic deformation is generated on the surface of the parts by means of a hydraulic sphere or cylinder. The main purpose of deep rolling is not to change the geometry of the workpiece but to improve the mechanical properties of the material by plastic deformation of the surface only [3]. During this investigation, aluminum alloy EN AW-6082 (AlSi1MgMn), which is frequently used in the manufacturing of suspension parts, will be examined. During this examination, different specimens were manufactured. Firstly; the aluminum samples were heat treated as T4 and T6. Despite T4 and T6 heat treated samples were prepared, only T6 was used for investigations, due to the fact that T6 is the commonly used material in the industrial fatigue applications. Secondly; T6 heat treated samples were subjected to tensile test to obtain flow curve of the material. During the tensile test; material was designed according to the tensile test standards of DIN 50125. Ultimate tensile and yield stress of the material were determined by tensile test. Additionally, in the recent studies showed that the compressive residual stresses in transverse direction are twice as high as in rolling direction on prismatic samples after deep rolling [4, 5]. However, residual stresses were not examined on both the tangential and longitudinal directions of cylindrical parts (Ø8 mm, Ø14 mm). Due to these reasons, it is aimed to model different sample geometries (prismatic, cylindrical) to investigate directional dependency of residual stresses on these samples. Also, distribution of residual stresses was examined with respect to three different feed parameters (0.1 mm, 0.2 mm, 0.3 mm). Subsequently, the results of residual stress distribution in these samples were compared with each others.