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  • Author: T. Piwowarczyk x
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T. Piwowarczyk1, M. Korzeniowski, P. Kustroń and M. Gąbka

ABSTRACT

The paper presents the potential of robotized welding applied for thin steel sheets using variable parameters of arc (different welding programs: Standard, Pulse, Twin Pulse, and Speed Pulse). Trial welded joints were made for sheets 0.8 to 1.25 mm thick and relevant welding parameters were selected for them during the first stage of examinations. The properties of welded joints were determined with non-destructive and destructive testing. In turn, visual inspection allowed to evaluate the shape and dimensional conformities of joints and to detect superficial imperfections. In order to improve detection accuracy, penetration testing was used for confirmation purposes. Tensile strength testing was also made to determine mechanical properties of the weld and the heat-affected zone. Metallographic examinations were used for sheets of all thickness values and for all welding programs to verify that the structure of joints was correct. All examinations and tests made on trial joints enabled to find how pulsing arc welding affects quality and strength properties of welds as compared with standard method.

Open access

M. Winnicki, T. Piwowarczyk, A. Małachowska and A. Ambroziak

Abstract

The paper deals with effect of working gas pressure and temperature on surface stereometry of coatings deposited by low-pressure cold spray method. Examinations were focused on aluminium coatings which are commonly used to protect substrate against corrosion. A commercial Al spherical feedstock powder with admixture of Al2O3 (Al + 60vol.-% Al2O3), granulation -50+10 µm, was used to coat steel, grade S235JR. Thedeposited coatings were studied to determine their stereometry, i.e. roughness, transverse and longitudinal waviness, topography of surface and thickness as the functions of gas pressure and temperature. A profilometer and focal microscope were used to evaluate the stereometric properties. In order to reduce the number of variables, the remaining process parameters, i.e. shape and size of de Laval nozzle, nozzle-to-substrate distance, powder mass flow rate, linear velocity of spraying gun, were kept unchanged. The investigation confirmed influence of temperature and pressure on coating thickness as well as on the surface seterometry.

Open access

M. Korzeniowski, T. Piwowarczyk, P. Kustroń and A. Czubak

ABSTRACT

The paper deals with the issues of welding modern car-body steels (including dual phase (DP), high strength low alloy (HSLA) and deep-drawing (DC) grades) using low-energy methods. In view of small thickness of elements to be joined, welding them with conventional arc methods has becoming more and more rare and has been replaced with methods which, while ensuring required strength properties of joints, deliver substantially less heat to the weld, thus limiting its effect on the structure being welded. Examinations (visual inspections, strength tests, hardness measurements) allowed an objective evaluation of selected low-energy methods with respect to MAG welding with CO2 shielding.

Open access

M. Winnicki, M. Rutkowska-Gorczyca, A. Małachowska, T. Piwowarczyk and A. Ambroziak

Abstract

The paper presents the study of microstructure and corrosion resistance of composite coatings (Al+Al2O3 and Cu+Al2O3) deposited by Low Pressure Cold Spraying method (LPCS). The atmospheric corrosion resistance was examined by subjecting the samples to cyclic salt spray and Kesternich test chambers, with NaCl and SO2 atmospheres, respectively. The selected tests allowed reflecting the actual working conditions of the coatings. The analysis showed very satisfactory results for copper coatings. After eighteen cycles, with a total time of 432 hours, the samples show little signs of corrosion. Due to their greater susceptibility to chloride ions, aluminium coatings have significant corrosion losses.