Mr. Ghomashchi, QUANTITATIVE MICROSTRUCTURAL ANALYSIS OF M-2 GRADE HIGH-SPEED STEEL DURING HIGH-TEMPERATURE TREATMENT, Acta materialia, 46(14), 1998, pp. 5207-5220
Citations number
17
Categorie Soggetti
Material Science","Metallurgy & Metallurigical Engineering
The microstructural changes of M2 grade high speed steel Were examined
quantitatively to identify the mechanisms responsible for changes dur
ing high temperature treatment. Reheating at high temperature leads to
major microstructural changes involving phase transformation, spheroi
dization and coarsening of carbides formed in the as-cast M2 grade hig
h speed steel. The M2C carbide decomposes rapidly to form MC and M6C i
n less than 1 h after attaining the reheating temperatures of 1150 or
1200 degrees C. Further reheating brings about the eutectic M6C carbid
e spheroidization and general coarsening of both M6C and MC. Carbide p
articles situated at the original austenite grain boundaries grow pref
erentially until impingement of carbides along these boundaries takes
place. It is the diffusion of tungsten in gamma-Fe which controls sphe
roidization rate of M6C carbides, while diffusion of vanadium and tung
sten in gamma-Fe is the rate controlling mechanism for coarsening of M
C and M6C carbides, respectively. The process of spheroidization of al
loy carbides such as M6C, is somewhat different from that of cementite
where impingement of the already spheroidized carbide particles make
the analysis more difficult. (C) 1998 Acta Metallurgica Inc. Published
by Elsevier Science Ltd. All rights reserved.