Ultrasonic impact treatment of the welded joint of aluminum-magnesium alloy produced by friction stir welding

The paper presents the results of ultrasonic impact treatment of the AMg5M alloy weld joint produced by friction stir welding, in order to eliminate defects in the root side of the weld. It was shown that ultrasonic impact treatment increases the microhardness of the surface layer caused by the accumulation of microplastic deformation during the impact

The microstructure of aluminum-magnesium alloy friction stir weld

Friction stir weld joint of aluminum/magnesium alloy has been structurally characterized after tensile testing. A butt-weld flaw which a surface of joining between two sheets has been revealed. This defect dictates the specificity of sample's fracture in a tensile test

The effect of friction stir welding tool wear on the weld quality of aluminum alloy AMg5M

Friction stir welding (FSW) tool wear has been studied from the standpoint of tribological layer generation and interaction of this layer with the tool’s metal. It was shown that during FSW on aluminum alloy the latter adheres to the tool’s working surface and then iron/aluminum reaction diffusion is initiated under the conditions of high mechanical stress and temperature. Since diffusion along the former austenite grain boundaries is much faster than volume diffusion, an intermetallic compound is formed inside the tool’s metal thus causing embrittlement and pulling out the tool’s metal fragments

Radiographic detection of defects in friction stir welding on aluminum alloy AMg5M

In order to reveal weld defects specific to friction stir welding we undertook radiographic inspection of AMg5M aluminum alloy welded joints. Weld defects in the form of voids have been revealed in the weld obtained under the non-optimal rotation and feed rate. Both shape and size of these defects have been confirmed by examining metallographically successive sections prepared in the weld plane as well as in the plane transversal to the tool feed direction. Linear defects have been also found in the sections that are not seen in the radiographic images. Both the preferable localization and origination of the defects have been analyzed

Wear resistance of steels under conditions of dry sliding friction and electric current of high density

The dependence of current density on the conductivity and the wear rate for the electric contact steel/steel 45 under conditions of dry sliding friction at current density higher 100 A/cm{2} has been presented. It has been determined that the increase in the content of alloying elements or reinforcing phase in the initial structure of the steel leads to lower strength of the surface layer, resulting in a high wear rate of contact and catastrophic wear at a low current density. It has been noted that the rapid destruction of the surface layer of alloy steels is caused by their low plasticity limits. The high values of wear resistance of non-alloyed steel at friction with current collection are due to the instability to the rotary and shear deformation, as well as to the formation of a viscous fluid on the sliding surface

Features of the microstructure development under conditions, reproducing the process of friction stir welding. Molecular-dynamics study

Friction stir welding is a recently developed technology which is used in various branches of modern engineering. The basis of this technology is the friction of the rotating cylindrical or specially shaped tool between two metal plates brought together either to meet their ends of one above another with the overlap. When applying the FSW process in various economical sectors, the important task is to study the mechanisms and identify the physical laws and factors leading to formation of structural inhomogeneities and discontinuities in the weld seam. This paper analyzes the basic mechanisms behind the structural state generation in the material subjected to severe plastic deformation and heating. To investigate the atomic mechanisms of structural changes in FSW, the modeling at atomic scale has been carried out. Results of work can be a basis for new knowledge about the microstructure evolution in FSW

Ultrasonic phase array and eddy current methods for diagnostics of flaws in friction stir welds

The feasibility of the defect detection in friction stir welds of aluminum alloys with the use of two different non-destructive testing (NDT) methods has been studied. We have used the following NDT techniques: ultrasonic phase array and eddy current methods. A metallographic examination was chosen as the third method. The weld flaws such as kissing bond boundaries, lack of penetration, voids and cracks have been successfully detected using the ultrasonic phase array technique. The eddy current method enabled the detection of a weld root flaw