Valery E. Rubtsov

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.

Thermography inspection of friction stir welding

The feasibility of thermography for detecting weld defects directly in the process of friction stir welding (FSW) is evaluated. Several types of temperature anomalies are revealed for friction stir welds, which are related to real seam defects, such as lack of penetration and wormholes found from the following metallographic examination.

Effect of Ultrasonic Application during Friction Stir Welding on Microstructure and Properties of AA2024 Fixed Joints

Microstructure and mechanical properties of aluminum alloy 2024 fixed joint produced by ultrasonic assisted friction stir welding are described. Tensile strength, microhardness, grain size and zone area are measured and compared with ones of joint produced without ultrasonic vibration. Analyzing this data authors make conclusion about ultrasonic vibration effect on friction stir welding joint quality.

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.

Microstructure of Fixed Butt Joints Formed by Friction Stir Welding on 2024T3 Aluminum Alloy

Friction stir welded butt joints on 2024T3 alloy have been obtained using two different process regimes. The microstructures of all the weld joint zones have been examined and such structural parameters as grain size, particle size and volume content of particles have been determined in order to find correlations with the microhardness of the corresponding zones.

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.

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.

Application of 3D Сomputed Microtomography for Investigating the Microstructural Defects of Carbon Fiber Reinforced Composite Made by 3D-Printing

The microstructural defect of additive manufactured 3-component carbon fiber reinforced polymer (CFRP) composites has been studied using computed microtomography. The samples have been prepared using a 3D-printing process developed at Skolkovo Institute of Science and Technology, Russia. The research procedure has been described and internal defects of the fiber composite material have been detected and analyzed using a 3D image reconstructed from a number of cross section views. The defects larger 50 μm have been detected using the computed microtomography test. Defect-free images and defects typical for this type of composites such as delamination in polymer matrix and between fibers in a bundle, fiber breakage have been obtained.

Structure and Worn Surface Morphology on Copper Containing Composites under Dry Sliding with High Contact Current Density

Dry sliding of the sintered composites of compositions Cu-graphite-Fe and Cu-Fe against steel at the contact current density higher 100 A/cm2 has been carried out. The presence of FeO oxide in surface layer was shown. The low content of FeO oxide resulted in high wear intensity. Formation of a liquid phase on a sliding surface was observed. Wear intensity was low in the presence of a liquid phase on the worn surface.

The Use of Laser-Doppler Vibrometry for Modal Analysis of Carbon-Fiber Reinforced Composite

Both modal analysis procedure and the results obtained on a three-component 3D-printed carbon-fiber reinforced composite (CFRC) are presented. Experimental modal analysis of on the composite has been carried out to obtain the dynamic behavior characteristics. As revealed, the different eigen-oscillations waveforms possess different sensitivity of its amplitude frequency response to structural defects of the composite. For the similar waveforms we observed the differences in eigen-oscuillation frequencies, vibration velocities and damping factors which can be caused by the presence of numerous defects homogeneously distributed in one of the samples.