In this paper, innovative resistance element welding (REW) technology for joining galvanized steel sheets to thermoplastics (PMMA) is introduced. The essence of the innovation is in the use of a special bimetallic joining element consisting of the core made of a Sn60Pb solder, and the sleeve made of a Cu tube. During resistance heating, the solder melts, thus allowing the formation of a metallurgical joint with galvanized steel sheet. Since Sn60Pb solder melting occurs at temperatures (from 183 to 190 °C) below the thermal decomposition temperature of most thermoplastics (for PMMA above 300 °C), there is no thermal destruction of the PMMA material around the joint. The mechanical fixation of the thermoplastic material at the overlap joint is provided by the sleeve made of Cu tube which has a substantially higher strength than a Sn60Pb solder.

The main trend in the automotive industry today is the reduction in vehicle weight. The problem is addressed first and foremost by the use of different types of light and high strength materials in the production of the car body. Although galvanized steel sheet is still the basic construction material, nowadays aluminium alloy sheets are increasingly used in the production of vehicles. This paper is focused on the optimization of process parameters by resistance spot welding dissimilar materials: galvanized steel sheet and sheet made of aluminium.K e y w o r d s : resistance spot welding, steel/aluminium joints, weld nugget, properties

The submitted paper deals with the simulation of thermal cycles during laser welding of aluminum sheets using Finite Element Method (FEM). After the design and creation of the simulation model, the simulation results were verified by the thermal cycles measured during the experiment on real samples. Verification has shown that, despite the differences that have resulted from some simplifications, the proposed model corresponds to the actual behavior of the material used during the laser welding process.

Current trend of maximum utilization of properties of metal materials forces the fabricators to use different materials for different construction parts. Thus the fabricators of welded constructions, such as automobile constructions, today combine cold rolled steel plates with high strength low alloy steel as well as with aluminium or its alloys. Especially metallurgical joining of steel to aluminium represents certain issues resulting from different physical properties (e.g. different melting point temperature). Following paper is focused on the analysis of utilization possibilities of plasma arc at the performance of zinc coated steel to aluminium heterogenic joints and on the comparison with the MIG process using the AlSi5 filler material. K e y w o r d s : joining of dissimilar materials, plasma arc welding, MIG welding, aluminium, coated plates

Under the influence of heat load and Zn diffusion in resistance spot welding of galvanized steel sheets, significant changes occur on the contact area of CuCrZr welding electrodes which lead to their erosion damage. Changes, causing wear of electrodes not only affect the welding process but also the quality and properties of the weld. Apart from the traditional solution (for example, the so-called "Slope" welding current) the wear of the contact surfaces can be affected by using the barrier layers -coatings. Main goal for the use of material barrier is to minimize the structural changes caused by Zn diffusion, erosion and higher heat resistance of the electrode. Recent studies have shown that such a suitable coating is a multilayer system (Ni/TiB2). This paper is focused on the assessment of changes in the contact area of the electrodes and the barrier layer Ni / TiB2 after compila-tion 0, 1, 5, 20 and 100 welds on galvanized steel sheets type HX220BD Z100MBO.