Aim of this thesis is to research new hot-wire TIG welding process for repair welding of tool steels. Repair of hot work tools is a complex procedure, which can be done in a significantly shorter time than manufacturing new tools. In order to meet required mechanical properties, it is crucial to select right welding parameters, filler material and post heat treatments. With a correct use of welding technology, it can prolong the life span of tool steels.
Theoretical part contains definition of tool steels, influence of alloy elements and heat treatments. Furthermore, there is a description of different factors on why tools fail, and recommendation for their repair welding. After an in-depth description of the principals of the TIP TIG hot-wire system, its cons and pros were listed in respect with other welding processes. Methodological approach is considered when selecting filler material and parameters. With the help of results of preliminary test, post heat treatment was selected. Vickers hardness tests and metallographic analysis were carried out, as well as determined tensile strength and fracture toughness. Results were analyzed based on the requirements of tool steels. Based on the research best results were obtained with solution annealing in three steps and ageing process.