The present study investigated the effect of electrode composition and buffer layer on the microstructure and mechanical properties of H13 tool steel repair welds. Three specimens were welded applying two conditions; i.e. with and without stainless steel underlay. The microstructure of all weld metals contained the martensitic matrix with distributed chromium carbide precipitations. The microstructure of the underlay was a mixture of austenite and layers of ferrite with the skeletal morphology. The results showed that hardness of the welded substrates with underlay was higher than that of the specimens without underlay. This difference could be more than 240 HV. However, the highest hardness values were obtained in the heat affected zone of welds. The application of tough underlay improved the weld toughness and bending properties of the welded specimens. Also, it encouraged the ductile fracture mode in weldments. Also, the higher hardness of weld metal could be resulted from the application of buffer layer.

Keywords: Hot work tool steel, Welding, Mechanical properties, Underlayer

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