Analyzing the heat-treatment effect on the mechanical properties of free-cutting steels

Abstract

In this research, the heat-treatment effect on the mechanical properties of free-cutting steels was investigated. Free-cutting steels (FCSs) are used where high degrees of machining are required as they increase the machining speed and reduce the tool wear. The effect of heat treatment on mechanical properties was identified using tensile and fatigue tests, and microstructure images taken with a scanning electron microscope (SEM). The studied material included commercially available AISI 12L14 cylindrical bars of free-cutting steel. FCS was heated to 900°C and held at this temperature for different time spans. The degradation of the mechanical properties of free-cutting steel due to the elevated temperature was assessed. At a microscopic level, more mechanical damage was observed between the steel matrix and the second phase of the heat-affected specimens. Keywords: fatigue, tensile strength, free-cutting steel, heat treatment V prispevku je bil raziskan vpliv toplotne obdelave na mehanske lastnosti avtomatnih jekel. Avtomatna jekla (FCS) se uporabljajo v primerih, ko so zahtevane velike stopnje obdelave, saj dopu{~ajo ve~je hitrosti rezanja ob manj{i obrabi orodja. Vpliv toplotne obdelave na mehanske lastnosti je bil dolo~en z rezultati nateznega preizkusa in preizkusa utrujenosti. Z vrsti~nim elektronskim mikroskopom (SEM) so bili narejeni posnetki mikrostrukture. Preiskovane so bile komercialno dosegljive palice iz avtomatnega jekla AISI 12L14. FCS je bil segret na 900°C in razli~no dolgo zadr`an na tej temperaturi. Dolo~eno je bilo zmanj{anje mehanskih lastnosti avtomatnega jekla zaradi povi{ane temperature. V toplotno obdelanih vzorcih je bilo z mikroskopom opa`enih ve~mehanskih po{kodb.

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