Analysis of indentation size effect on hardness and fracture toughness of hard metal

U ovom radu su prikazani tvrdi metali s osvrtom na njihova svojstva, primjenu i postupak proizvodnje. U radu je analiziran utjecaj opterećenja na tvrdoću i lomnu žilavost tvrdog metala. Tvrdoća je mjerena metodom po Vickersu s četiri različita opterećenja: 29,42 N (HV3), 49,03 N (HV5), 196,13 N (HV20) i 294,20 N (HV30). Lomna žilavost je određena mjerenjem duljine pukotina koje se šire iz vrhova otiska. Pri tom su primjenjena četiri različita modela otpornosti lomu po Palmqvistu, Anstisu, Casellasu i Niihari. Dobiveni rezultati ukazuju da vrijednosti tvrdoće i lomne žilavosti variraju s obzirom na opterećenje utiskivanja indentora, a dodatno lomna žilavost ovisi i o modelu lomnog ponašanja.In this master degree work are shown hard metals with review on their properties, application and manufacture process. In this work is analysed indentation size effect on hardness and fracture toughness of hard metal. Hardness was determined by method of Vickers, for four types of loads 29,42 N (HV3), 49,03 N (HV5), 196,13 N (HV20) i 294,20 N (HV30). Fracture toughness was determined by measuring crack length that spreads from indent tips. For that are applied four models of crack resistance: Palmqvist, Anstis, Casellas and Niihara. The results obtained show that the value of hardness and fracture toughness vary considering indentation load, and fracture toughness also depends on model of cracking behaviour