Indentation creep and tribological characterization of AISI 321, AISI 431 and FDMA borided and non-borided steels

Abstract

In this paper, the mechanical properties, the creep and the tribological behaviours of three borided and non-borided steel materials were analysed. The alloy steel substrates were borided by a powder-pack boriding process during 8 h at 950 °C. The creep process during the holding stage of nanoindentation test was analysed using various mathematical models. The tribological properties of the studied materials were investigated by wear experiments on a ball disc test wearing. It was found that the corresponding indentation creep behaviour can be correctly described by a power-law relationship. Furthermore, based on the selected power-law creep function, the stress exponents and the corresponding strain rate sensitivity (SRS) indices were also determined. In particular, boride layers showed excellent mechanical properties and they were found to be more creep and wear resistant compared to base steel substrates. Furthermore, with an increase in applied load, the wear tests revealed an increase in wear loss and a decrease in the friction coefficient.