The mechanical properties and microstructure of weldments are always an imperative concern of researchers; therefore, the change from continuous gas tungsten arc welding (GTAW) to pulsed-current gas tungsten arc welding (PCGTAW) was investigated for alloy 690, using the autogenous welding method. The mechanical properties like the tensile strength and impact were examined for both variants (continuous and pulsed-current gas tungsten arc welding). The microstructure was the susceptible

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... revealing a complete formation of the weldments. Hence, a complete analysis with an optical microscope of up to 400 μm and a SEM of up to 7000 μm was performed during the described examination. This analysis showed that the formation of the secondary phase was negligible in the case of the pulsed-current method, which was superior to the gas tungsten arc welding, exhibiting a tensile strength of 641 MPa and an impact strength of 66 J. Mehanskim lastnostim in mikrostrukturi zvarov raziskovalci vselej posve~ajo {e posebno pozornost. Zato so avtorji~lanka raziskovali prehod s kontinuirnega oblo~nega varjenja z volframovo elektrodo v za{~itnem plinu (GTAW) na pulzirajo~e tokovno oblo~no varjenje z volframovo elektrodo pod za{~itnim plinom (PCGTAW) zlitine Inconel 690 z uporabo autogene (brez dodajnega materiala) varilne metode. Dolo~ili in primerjali so mehanske lastnosti (natezno trdnost in udarno'ilavost) obeh razli~ic varjenja (kontinuirno in tokovno pulzno oblo~no varjenje z volframovo elektrodo pod za{~itnim plinom). Popolna tvorba mikrostrukture zvarov je bil odlo~ujo~parameter oz. kriterij. Izvedli so kompletno metalografsko analizo pod opti~nim mikroskopom do 400 μm in z vrsti~nim elektronskim mikroskopom (SEM) do 7000 μm. Te analize so pokazale, da je pri{lo do zanemarljive tvorbe sekundarnih faz v primeru metode s pulzirajo~im elektri~nim tokom. Ta metoda (PCGTAW) je bolj{a od oblo~nega varjenja z volframovo elektrodo pod za{~itnim plinom (GTAW), ker sta bili dose'eni precej vi{ja natezna trdnost (641 MPa) in udarna'ilavost zvara (66 J). Klju~ne besede: postopek PCGTAW, postopek GTAW, mehanske lastnosti, SEM