Andrzej Kolasa

Structure and mechanical properties of MIG welded butt-joints of magnesium alloys

This article presents an assessment of the structure and the mechanical properties of butt joints of as-cast magnesium alloys AZ91, AM-Lite and AM50 welded with the MIG welding method. The shielding gas used was a mixture of argon and helium. The macro- and microstructures were evaluated by means of a light microscope and a scanning electron microscope using metallographic specimens cut along a plane perpendicular to the welding direction. An analysis of the distribution of alloying elements has been performed with the use of the scanning electron microscope. The mechanical properties of joints have been evaluated on the basis of microhardness distribution in the joints and tests of the bending and tensile strength of weld joints. The results of this assessment show that it is possible to achieve high quality butt joints of magnesium alloys with the use of the MIG welding method. Trace amounts of porosity have also been observed in the joint area.

Study of static and dynamic characteristics of welding power source-arc systems

Each arc welding method has its own characteristics resulting from the range of process parameters used, properties of the welding arc (chemical composition of the arc environment, type of electrode, etc.) as well as the mode of metal transfer, thus creating specific requirements regarding both static and dynamic welding power sources. This article presents selected aspects concerning the determination of output characteristics of welding power sources based on previous studies as well as the prospect for further research.

Electromagnetic compatibility of power supplies for arc welding

Electromagnetic compatibility (EMC) is often associated only with radio interference. But another significant component of EMC is generation of harmonic components of electric current and voltage by a device that has an impact on a mains circuit and that could be a reason for considerable losses of supplied energy. The acceptance limits of generated interruptions are specified in both Polish and European standards which, as a result of a quick development of electrical appliances, are frequently updated. This paper presents comparative test results of interruptions generated by selected welding instruments ranging from transformer inverters for both hobby and workshop purposes, up to professional industrial devices.

Structure of butt joint of as-cast magnesium alloys

The article presents a structural analysis of joints of as-cast magnesium alloys created using three joining methods: friction stir welding, CO2 laser welding and electric arc welding in inert gas shielding using tungsten electrode (TIG). The macro- and microstructures of the butt joints have been evaluated using an optical microscope with a digital image recording system. Two types of magnesium alloys were used in the research: AZ91 and AM-Lite, the main alloying elements of which are zinc and aluminium. The starting material consisted of cast ingots milled to a specific dimension and then cut into plate samples with a thickness of 3 mm. The subsequent analysis showed that it is possible to achieve high-quality joints of magnesium alloys. However, trace quantities of pores have also been found.

Modelowanie i wdrożenie wysięgników do lokomocji robotów przemysłowych; Modelling and implementation of movable booms for industrial robot mobility

Ustalenie odpowiedniego położenia robota przemysłowego względem miejsca pracy, w pełni wykorzystującego jego potencjał manipulacyjny, ma kluczowe znaczenie dla prawidłowego funkcjonowania stanowiska produkcyjnego. W przypadku robotów pracujących w pozycji odwróconej, oprócz rozwiązań stacjonarnych, można spotkać nieliczne przykłady ruchomych wysięgników o charakterze zewnętrznej osi robota. Tego typu lokomocja, pomimo potencjalnie mniejszego zasięgu w stosunku do torów jezdnych, skutkuje łatwością instalacji oraz zwykle niższymi kosztami. W artykule przedstawiono proces opracowania i wdrożenia do produkcji seryjnej nowych konstrukcji ruchomych wysięgników do lokomocji robotów przemysłowych.

Friction stir welding of AZ-91 and AM-Lite magnesium alloys

The objective of this paper was to report the results of butt joint quality of friction stir welding (FSW) of samples of alloys of MgAlZn group. Welding has been carried out with the FSW tool of welding speed ranging from 140 to 355 mm/min. In the stir zone and the surrounding, neither porosity nor cracks have been obtained. Microhardness in the stir zone increased for all welds when compared to the base metals, as a consequence of the high grain refinement and increased precipitations at the grain boundaries. The decrease in plastic properties of metal in these regions is expected. The results show a strong relationship between properties of joints and welding parameters.