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An important point in Tribology is mechanical-dynamic testing of lubricants and materials under stress and the interpretation of the results obtained therefrom. Widely-used test methods are often applied to test the performance of lubricants e.g. test results determined by tribometers should be treated carefully when using marketable oils. A closer evaluation of these results is part of this research paper. Within this study, several marketable oils were used and experimentally investigated. These were a gear oil, two engine oils, one hydraulic oil, one metal working fluid and one forming oil. There were several distinct differences. On the one hand, the used oils differ significantly in terms of their performance in the individual test methods. This is not surprising but has a clear reason in the different compositions of the lubricants resulting from their respective application. By subjecting these oils to diverse test methods with different test equipment, the results can vary widely and result in completely dissimilar results from the tests. Thus, a metalworking oil appears excellently when determining the welding force in the four-ball apparatus. In the high frequency liear oscillation tester, on the other hand, barely usable results are generated. Thus, there are two contradictory statements that should be the same.

Study of weld joints of nonferrous, Inconel 625 alloy sheets using a new generation disk laser as the green welding technology for the effective manufacturing were carried out, and the results are presented in this paper. Weld joints of the Inconel 625 alloy sheets 2,0 mm thick were welded by laser without an additional material at a flat position, using a high purity argon as the shielding gas. The influence of laser welding parameters on weld quality and mechanical properties of test joints was studied. The influence of welding speed and laser power to the joint quality was investigated. The study of quality and mechanical properties of the joints were determined by metallographic evaluation, tensile and hardness tests.

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