GJS 400-15 ductile cast iron has excellent physical-chemical, mechanical-structural and manufacturability properties. However, it has notable limitations when it is subjected to the welding operations to which it is subjected. The objective of this work is the characterization of the welds made in GJS 400-15 ductile cast iron parts, specifically 6mm thick sheets, to determine their applicability based on the mechanical and microstructural properties obtained. For this, several welding procedures have been proposed, in which an Fe-Ni alloy is used as a filler material and SMAW and TIG welding techniques are combined with different heat treatments. The mechanical characterization tests have been based on tensile analysis and hardness determination. As for the micrographic analysis, it has been carried out through the micrographs of the thermally affected areas (base metal, interface and welding. TIG welding, in general terms, has been effectively effective in the welding processes of nodular cast iron sheets despite its disadvantage in the results obtained compared to the SMAW technique. On the contrary, the advantages that the TIG welding technique presents in terms of execution time and more favorable cost open a way to the development, technical evolution and industrialization of the welding processes carried out using this last technique. It is hoped that the study will present a positive contribution to the technological development of welding processes and their industrial application to the manufacture, maintenance or repair of parts and products in which ductile iron is present and especially those formed by steel plates. small thickness. Keywords: ductile cast irons welding, SMAW, TIG, heat treatments, preheating, annealing, traction, hardness, micrograph