Global and Local Mechanical Properties and Microstructure of Friction Stir Welds with Dissimilar Materials and/or Thicknesses

Abstract

This article studies the properties of a wide range of friction-stir-welded joints with dissimilar aluminum alloys or thicknesses. Two aluminum alloys, namely, 2024-T3 and 7075-T6, are selected for the study and are welded in ten different combinations of alloys and thicknesses. The welding parameters are optimized for each configuration, and a systematic study of the effects of material and thickness combinations on the microstructural features, global and local mechanical properties, and fracture mechanisms of the welds is carried out. It is shown that dissimilar alloys are extruded into each other, the texture is heterogeneous in the weld zone, and that there is no significant diffusion of alloying elements between the alloys. For most configurations, the local and global mechanical properties decrease as the thickness ratio increases. The local yield strength and plasticity parameters substantially vary next to the weld centerline, hence requiring their implementation in finite element method (FEM) models. Machining to obtain a constant thickness significantly influences the mechanical properties of the welds. The fracture mechanism is found to be a mixture of ductile and brittle fractures and to qualify as ''quasi-cleavage.''

Elevated temperature low cycle fatigue of a gravity casting Al–Si–Cu alloy used for engine cylinder heads

“…Aluminum alloys, as fcc materials, are generally considered to fail through ductile fracture mechanism, whereas cleavage fracture appears in the fcc materials only under special circumstances [34], which is mainly due to the numerous active slip systems in fcc materials [35]. On the other hand, this implied that fatigue crack propagated ϭϰ along an individual slip band (or parallel slip bands) within the matrix under this condition.…”

Mechanical behaviour of dissimilar friction stir welded tailor welded blanks in Al–Mg alloys for Marine applications

“…They highlighted the influence of process parameters, tool geometry, and the double tool inclination angle on the production of sounds TWB joints. Zadpoor et al [5,6] evaluated FSW joints produced with dissimilar aluminium alloys (AA2024-T3 and 7075-T6) and thicknesses (in the range 2-2.5mm). The global and local mechanical properties were assessed in quasi-static tests, and the microstructural features were characterized.…”

Analytical Relationships for Nanoindentation-Based Estimation of Mechanical Properties of Biomaterials

“…For example, one could use full-field strain measurement techniques such as digital image correlation 100,106,107 for obtaining the local mechanical properties of heterogeneous materials. 108,109 It is suggested that the accuracy of mechanical properties measured using nanoindentation be compared with those measured using other advanced techniques at least in some test conditions.…”