engleski

CORRELATION BETWEEN MICROSTRUCTURE, HARDNESS AND FRACTURE TOUGHNESS OF HEAT-TREATED HIGH-SPEED STEEL

The correlation between microstructure, hardness and fracture toughness 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 specimens which 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. By means of heat treatment, the microstructure of high-speed steel can be changed. Due to secondary hardening under different tempering conditions, high-speed steels can obtain the same hardness but different microstructures and consequently different fracture toughness. Therefore, the optimization of the parameters of vacuum heat treatment of high-speed steels is a worthwhile task.

Vacuum heat treatment; High-speed steel; Microstructure; Volume fraction of undissolved eutectic carbides; Volume fraction of retained austenite; Correlation between hardness and fracture toughness.

nije evidentirano