EFFECT OF PLASMA HARDFACING AND CARBIDES PRESENCE ON THE OCCURRENCE OF CRACKS AND MICROCRACKS
Lazar Jeremić1, Branislav Đorđević2, Simon Sedmak2, Aleksandar Sedmak3, Marko Rakin4, Mihajlo Aranđelović2
1) Saipem, Milano, Italy
2) University of Belgrade, Innovation Centre of the Faculty of Mech. Eng., Belgrade, Serbia
3) University of Belgrade, Faculty of Mech. Eng., Belgrade, Serbia
4) University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia
Presented is the effect of plasma hardfacing (or just hardfacing) and carbides presence on the occurrence of cracks and microcracks in the welded layer. The reasons behind this phenomenon are analysed and explained. In addition, the plasma welding technology with all the necessary data such as welding parameters is shown for the case of undamaged tooth of a machine used for the milling of marble. The welded layer with a significant amount of tungsten-carbide is applied onto new, undamaged tooth in order to improve the characteristics of the surface layer of the base material by increasing its hardness which leads to increasing of wear resistance and impact toughness. After welding, the tooth is cut using electrical discharge machining (EDM) for examining the applied surface layer in different locations throughout the welded joint. Macro and microstructural analysis aided in determining the characteristics of the surface layer. The nature and causes of cracks and microcracks are analysed in order to provide a better solution to avoid crack occurrence, as well as in determining their potential effect on the integrity of the tooth as a whole.
Keywords: plasma welding, hardfacing, carbides, cracks, microstructure