Friction stir processing on carbon steel

Friction stir processing of medium carbon steel samples has been carried out using a milling machine and toolsmade of cemented tungsten carbide. Samples have been machined from 40 and 40X steels. The tools have been made inthe shape of 5u5u1.5 mm and 3u3u1.5 mm tetrahedrons. The microstructure of stirred zone has been obtained using thesmaller tool and consists of fine recrystallized 2–3 Pm grains, whereas the larger tool has produced the “onion-like”structures comprising hard quenched “white” 500–600 MPa layers with 300–350 MPa interlayers of bainite needles. Themean values of wear intensity obtained after measuring the wear scar width were 0.02 mm/m and 0.001 mm/m for nonprocessedand processed samples, respectively

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

Surface layer structure of AISI 1020 steel at different stages of dry sliding under electric current of high density

Wear intensity of the sliding electric contact steel 1020/steel 1045 depending on sliding time is presented at the contact current density higher than 100 A/cm{2} without lubricant. It is shown that wear intensity of 1020 steel decreases at increasing of sliding time. Wear intensity is stabilized after some sliding time. This time (burn-in time) decreases at reduction of current density. Structural changes are realized in surface layer. Signs of liquid phase are observed on sliding surface. This liquid isn't a result of melting. It is established using Auger spectrometry that the contact layer contains up to 50 at.% of oxygen

Wear Resistance of Friction Pair of Metal Composite/Copper under Electric Current

Sliding of metal composites against copper counterbody under severe conditions (i.e. at the contact current density higher 50 A/cm{2} and at high roughness of counterbody) is carried out. It is shown that the composite of composition of Cu-30% of graphite shows low wear resistance in these conditions. Higher wear resistance is inherent in the composites containing lead and bearing steel. Impregnation of these composites by industrial oil hasn't led to noticeable increase in wear resistance

Quality Estimation of Dry Grinding of Skiving Cutters With Organic Bonding Diamond Wheels

Engineering process preparation requires proper preparation of cutting tools. It influences not only the performance of the tools but also the quality of workpiece surface machining. One of the promising environmentally friendly trends of mechanical treatment is grinding without using lubricating cooling liquid. This method can considerably influence the quality of cutting tools grinding. Smoothing skiving turning is an effective treatment method providing high efficiency and workpiece quality. Proper preparation of cutting edges is especially important in this process. For that purpose we have carried out a research in grinding changeable carbide inserts for skiving turning by means of grinding wheels with different grain size. The influence of different combinations of wheels on roughness of the inserts front and rear surfaces and quality of cutting edge was studied with the help of laser confocal microscopy

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

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 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