Dragan Pustaić

Influence of heat treatment of high-speed steel on its microstructure, hardness and fracture toughness

The correlation between fracture toughness, hardness and microstructure of vacuum heat-treated high-speed steel AISI M2 was investigated. Our intention was to investigate the influence of microstructural parameters such as the volume fraction of undissolved eutectic carbides, their mean diameter, the mean distance between the carbides, as well as the volume fraction of retained austenite in the matrix, on the above mentioned mechanical and fracture properties. The experimental investigations were performed on the high-speed steel. This steel had the following chemical composition (mass content in %): 0.89% C, 0.20% Si, 0.26% Mn, 0.027% P, 0.001% S, 3.91% Cr, 4.74% Mo, 1.74% V and 6.10% W.

Influence of Heat Treatment on Crack Tip Opening Displacement and on Resistance of Crack Propagation of Alloyed Steel

The aim of the performed investigations was to determine the influence of two different heat treatment procedures, i.e. hardening and tempering vs. austempering, on some mechanical properties, as well as the influence of these procedures on the magnitude of some fracture mechanics parameters for example, crack tip opening displacement (CTOD) and J-integral. The experimental investigations were performed on the specimens made of spring steel 65Si7 (chemical composition: 0.69% C, 1.56% Si and 0.90% Mn).

Influence of Hardening and Tempering Vs. Austempering on Mechanical and Fracture Properties of 65Si7 Steel

The aim of the performed investigations was to determine the influence of two different heat treatment procedures, i. e. hardening and tempering vs. austempering, on some mechanical properties, such as strength, hardness, ductility, contraction, toughness etc., as well as the influence of these procedures on the magnitude of some fracture mechanics parameter for example stress intensity factor K. The experimental investigations were performed on the specimens made of 65Si7 steel (chemical composition: 0.69% C, 1.56% Si and 0.90% Mn).