Two welding technologies (EBW, GTAW) were used to weld thin Mo sheets. Sheets thick 0.2 mm were welded by EBW and 0.4 mm thick samples were welded by GTAW welding methods. Welds were tested by means of metallography, optical microscopy, hardness measurement, chemical analysis etc. Mo welding is difficult because of inherently low ductility of Mo and high affinity to oxygen. Experiments proved that EBW is much better for welding thin Mo sheets, because it is done in vacuum and has much lower heat input. HAZ width of EBW was 1.4 mm compared to more than 35 mm for GTAW weld.

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Heterogenous welds of Nitinol and austenitic stainless steel 304 were done by micro plasma welding. Both materials have wide utilization in medicine, especially NiTi is very promisive material, but with rather difficult weldability. The quality of welds was estimated by means of metallography, hardness measurement, and tensile strength test. It was found out that homogenous welding of NiTi as well as heterogenous NiTi+304 welds very much decreases mechanical properties. In homogenous weld, strength, hardness drops to 260 HV (BM 350 HV) because of grain growth. Heterogenous welds have high hardness, up to 800 HV caused by precipitation of brittle intermetalics. PAW was found not to be suitable for nitinol welding.

Research work is focused on welding of fine grained nomalised steel S355NL with high thickness 50 mm for crane construction. Double sided V-groove butt weld done by GMAW with filler OK Autrod 12.60. Welding parameters and cycle were designed according to norm EN 1011-2. Carbon equivalent, parameter U.C.S. served to set preheat and interpass temperature. No weld heat treatment was used. Destructive and non-destructive testing served to certify used welding process.

This article presents research of weldability of aluminium alloys. The research was done at Faculty of Mechanical Engineering, CTU in Prague. In the rolling stock production often used precipitation hardenable Al alloy AlMg1Si1Mn was subjected to the hot cracking weldability test to research its susceptibility to hot cracking during GMAW. Base material and 3 recommended filler wires are subjected to T-joint weld cracking test. As filler wires AlSi5, AlMg4.5MnZr and AlMg5Cr were selected and welding method is GMAW. Tjoint weld cracking test is usable test standardized for evaluation of hot cracking, but as the result of this research it was found, that its sensitivity is very low and other weldability test has to be used to asses weldability properly.