International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

This paper presents an overview of hybrid technologies for joining dissimilar materials in automotive applications. CMT welding/brazing technology has been experimentally verified for the purpose of joining dissimilar steels or steels and aluminium alloy. Two types of filler material were used, one based on Cu and the other based on Al. When joining dissimilar steels, a true brazed joint was formed, while when joining steels and aluminium, a hybrid – welded/brazed joint was formed. Subsequently, metallographic analysis of the joints and testing of their load carrying capacity was carried out.

The paper focuses on the application of friction stir welding (FSW) technology for welding of unequal materials based on aluminum alloys. Joints were made from AW 5083 and AW 6082 materials using FSW technology at different weld speed values. The joints were analyzed metallographically, the hardness of the materials was tested across the cross section of the joint and the strength of the joint was tested by destructive static tensile test. At the lowest weld speed, the materials were not perfectly mixed, there was a macroscopically visible gap at the joint location, which was reflected in the lack of joint strength. At the medium and highest weld speed values, a joint with mechanical properties comparable to those of the base material was formed. Metallographically, the bond between the materials was free of any internal defects.

This work deals with corrosion measurements of galvanized steel HCT600X+Z subjected to progressively increasing plastic strain. The corrosion resistance measurements were carried out by non-destructive EIS (electrochemical impedance spectroscopy) test and destructive LP (linear polarization) test. As a result of the work, the measured data were analyzed and the results were processed using Nyquist diagram and Tafel analysis.

This paper deals with the investigation of the effect of speed on the form fit joint of dissimilar materials. Thin -walled materials based on steel and aluminium alloy were joined by thermal drilling. The shape and size of the resulting bushing were evaluated. It turned out that the best material combination for joining by flowdrill technology are joints made of steel and aluminum alloy. Aluminum alloy must always be placed in the bottom position. The best parameters of the formed bushing were achieved with the combination of DC-Al or TL-Al materials, at tool speeds of at least 2400 rpm.

The paper presents the results of testing the joints of unequal materials using flow-drill technology and a combination of flow-drill technology and adhesive bonding. The formed joints were tested by tensile and shear test according to ISO 12996. The positive effect of adhesive bonding on the load-bearing capacity of the joints and on the stress distribution in the tested materials was observed.

The paper provides an overview of the load-bearing capacity of joints of the same and unequal thin steel sheets formed on different pretreated surfaces by adhesive bonding. Four types of surface preparation and rubber-based adhesive were tested. The joints were subjected to a climatic test according to VW: PV1200. The change in the load-bearing capacity of the joints was evaluated on the basis of the force at the joint failure, the type of failure and on the basis of the load to displacement ratio.

The paper presents results of research aimed at comparing selected properties of two types of pipe steels, conventional 17G1S-U steel and alternative S960QL steel. The steels were compared in terms of their chemical composition, microstructure, hardness and corrosion resistance. Static electrochemical corrosion tests were performed on the materials, namely electrochemical impedance spectroscopy (PEIS) and linear polarization (LP) in two electrolytes. The results show different chemical composition and microstructure of materials. 17G1S-U steel has a row-like ferritic-pearlitic structure with a hardness of 200 HV 0.1. S960QL steel has a martensitic structure with a hardness of 353 HV 0.1. Steels showed very close corrosion rate in both electrolytes.

The paper is focused on research results of dissimilar materials joining by adhesive bonding. Galvanized and non-galvanized steel sheets with a thickness of 0.8 mm were joined together. To compare the effect of the presence or absence of the Zn layer on the strength of the adhesive joints, control joints were made, consisting only of galvanized and only of non-galvanized materials. The materials were joined on one hand without any surface preparation, and on the other hand prepared by degreasing and mechanical roughening with sandpaper. Epoxy/PVC-Polymerblend adhesive with glass beads was used for bonding to check the thickness of the adhesive. The tensile lap-shear strength was tested according to DIN EN 1465. The joints made of galvanized materials only proved the highest, the joints made of nongalvanized materials only proved the lowest shear strength. The mixed joints did not reach the joint strength of galvanized materials, but exceeded the joint strength of non-galvanized materials. The adhesion of the adhesive to non-galvanized substrates seems to be the limiting factor of the strength of mixed joints

The paper presents the results of the research aimed at determining the quality of coatings applied by the HVOF spray coating technology and the advances in its application. WC-Co-Cr 86/10/4 nano covers were evaluated at two grain sizes. The effect of nano particle size on coatings quality was evaluated under abrasive wear conditions with bound abrasive in the initial state and after thermal cyclic loading. Coating thickness measurements, microhardness and structural analysis of the coatings were performed. As the number of thermal cycles increased, the hardness of the coatings increased. A thermal load between 600 and 800 ° C results in the crystallization of the amorphous phase, which leads to the precipitation of the WC phase from the Co-Cr matrix, and thus to an increase in the microhardness of the coating. The REM analysis of the structure of nano coatings confirmed that the exposure of the samples to the thermal load had an influence on their structural  composition. As the number of thermal cycles increased, the wear of the coatings under dry friction conditions increased.

The paper deals with the problem of occurrence of internal defects in materials produced by SLM technology. The influence of the position of materials on the platform during the SLM on selected properties – porosity and corrosion resistance were examined. The reuse of non-compacted powder (three times recycled powder) and its effect on porosity and corrosion resistance of materials was also tested. Porosity was measured on metallographic sections in two perpendicular directions by image analysis, corrosion properties were tested by linear polarization method.