ABSTRACT The solidification structure of the as-cast consists of the matrix structure that is predominantly
austenite and precipitated chromium carbide along the grain boundary. Under these
circumstances and where the level of impact is relatively modest, such alloys in as-cast condition
will perform. However, at higher levels of impact energy, a point is reached where excessive
stress are built up within the component and eventually the materials strength is exceeded and
the outcome is complete failure in a characteristic stress fracture mode. If this is to be prevented,
it is therefore imperative that the casting be subjected to appropriate heat treatment, to obtain a
structure which consist of Cr7C3 carbide and martensite at a hardness range of 650-750HB. The microstructure of NF6357A cast chromium steel containing 2.59% C- 0.7%Si-0.91%Mn-18.54%Cr-0.019%P-0.01%S- balance–Fe after appropriate heat treatment such as quenching and tempering process have been characterised by means of optical microscope, micro hardness tester, optical emission spectrometer and charpy testing machine. The results show that oil quenched samples were found to retained microstructural consistency for casting thicker than 120mm section. For economic argument, air quenched castings of less than 120mm thickness is not only cheaper alternative, but it is also environment friendly. The fracture toughness was
found to be fairly consistent between 2.4-2.6%C range. However, at higher carbon level, the
fracture process is dominated by the presence of segregated carbide network which act as a
weak link in the microstructure. This weak link encourages dislocation pile-up and impaired
Cite this paper
J. Agunsoye, V. Aigbodion and O. Sanni, "Effect of Heat Treatment on Microstructure and Mechanical Properties of NF6357A Cast Alloy for Wear Resistance Application," Journal of Minerals and Materials Characterization and Engineering, Vol. 10 No. 11, 2011, pp. 1077-1086. doi: 10.4236/jmmce.2011.1011082.
 Zhang MX, Kelly PM, Gates JD, Journal of materials science, Vol 36 ,No16, 3865-3875.
John Udodua, Quality Control Report Nigerian Foundry Limited. Vol 2, No 6, 20-21, July
Mhasshimoto Int. Conf. on ‘’Abrasion Wear Resistance alloyed White Cast Iron for rolling
and pulverising Mills’’ Fukuoka Japan, August 16-20, 2002 yesu hiro matsubara 195-206.
A. Sinatra: Int Conf on ‘’Abrasion Wear Resistance alloyed White Cast Iron for rolling and
pulverising Mills’’ Fukuoka Japan, August 16-20, 2002 yesuhiro matsubara 23-31.
G. Laird: AFS Trans, 1991, 99. 339-357
Kogi Y. Matsubara and K .Matsuda: AFS Trans 1981, 89, 197-294