The wear behaviour of niobium alloyed cast high speed steels under cuttuing conditions
Abstract: The consumption of high speed tool steels used as cutting tool materials in
conventional turning lathes are quite high. The aim of this work is to investigate the
cutting and wear behavior of a high speed tool steel that can be used as cast without
rolling and to characterize its microstructure. Alloy is designed with a chemical
composition that differs from the common alloys and niobium is used for this purpose
with titanium additions. Niobium helps to obtain controlled precipitation of
monocarbides from the liquid phase. Thus, the formation of interdendritic eutectic
carbide films are prevented partially and thougness is increased since such films are
undesirable in the microstructure because they cause interdendritic brittleness. High
speed tool steel parts in varying sizes are manufactured by chill and sand supported
sheet moulds, have been subjected to a series of heat treatments like austenitizing,
quenching and tempering. At the all stages of the production, samples are taken and
microstructure and image analysis are carried out, thermocalc programme is utilized to
calculate the amounts of the phases present under equilibrium conditions. Produced parts
and standard cutting tools, that are purchased from the market for comparison purposes,
are used at turning lathe to machine various materials. The flank wear and crater depths
caused by catastrophic wear are measured at given intervals of machining process. Also
trials are carried out by boron additions to the newly developed cast high speed tool steel
and parts as forming material. Microstructure analysis and calculations by thermocalc
programme are carried out.
Alpay Yılmaz
Niobyum alaşımlı döküm yüksek hız çeliklerinin kesme koşulları altında aşınma davranışı · 2006 · 195 sayfa.
Danışman: Prof.Dr. Şadi Karagöz
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