The paper presents results of a metallographic examination of padding welds made by TIG method in almost unweldable casting superalloy Inconel 713C. During the research, microstructural changes were observed and identified in padding welds, in heat-affected zone and in cracked areas. The created phases were identified and their morphology characterised in the fused zone and in the cracked areas. In the research, the methods of light, scanning and transmission microscopy as well as X-ray structural analysis were applied. It was found that structure of the padding weld showed nanostructural features and the present cracks were caused by stresses resulting from low thermal conductivity of the alloy, high crystallisation velocity and interdendritic microporosity. The cracks observed in the heat-affected zone were caused, beside high thermal stresses, also by precipitates of secondary M6C type carbides with lower melting temperature and by creation of low-melting eutectics (γ\-γ\’) with precipitates of secondary carbides MC and M₆C.

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