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A D V A N C E D M A T E R I A L S & P R O C E S S E S | J A N U A R Y 2 0 1 7
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Finally, Prof. John Jonas from
McGill University discussed how the
study of meteorite microstructures
could be used to better understand
microstructure formation fundamen-
tals. Because meteorites cool extremely
slowly (around 1°-100° C per million
years), the microstructures that form
do so in near-equilibrium conditions,
allowing observation of phase transfor-
mations that occur over time periods
not practical in laboratory tests. This
understanding can then be compared
and contrasted to phase transforma-
tions that occur during manufacturing
processes such as rolling.
Inmeteorites, phase growthoccurs
slowly and in the absence of stress; in
rolling, transformations are rapid and
occur under stress. The use of electron
backscatter diffraction (EBSD) shows
that the applied stress during rolling
allows rapid ferrite formation at tem-
peratures above those for equilibrium
conditions, and also produces prefer-
ential crystal orientation selection with
respect to rolling directions. In addi-
tion, ferrite formation during rolling
results in softening and load drops as
well as physical volume increases. This
understanding allows metallurgists to
better understand the phase transfor-
mations that occur during processing,
design tailored processes to manipu-
late microstructure development, and
improve the materials produced by roll-
ing processes.
SUMMARY
All six speakers in this special
symposium shared examples of the
importance of understanding how the
specific manufacturing process affects
microstructure development in met-
als. The fundamental understanding
of microstructure allows metallurgists
to select manufacturing processes and
schedules to tailor the microstructure,
and therefore mechanical proper-
ties and performance, for a particular
component.
Moving toward the future, con-
tinued improvements in the control
of manufacturing processes and the
ability to test and characterize mate-
rials will enable substantial further
improvements in manufacturing capa-
bilities. Metallurgists who understand
this relationship will be better able to
exploit technological advances and
provide great benefits tomanufacturing
and society. It is critically important for
industry to promote the education and
training of metallurgists to ensure ad-
vanced understanding and capabilities.
Further reading related to each
topic is referenced below. These sym-
posia were organized through the AIST
Metallurgy: Processing Products and
Applications Technology Committee
(MPPATC) and will be organized for a
third time at MS&T18. Contact Kes-
ter Clarke ) if you
would like to participate in the future or
have topic ideas of interest. ~AM&P
For more information: Kester Clarke
is assistant professor, Colorado School
of Mines, 1500 Illinois St., Golden, CO
80401, 303.384.2301, kclarke@mines.
edu, .
References
1. “The Age of Bessemer Steel,” pre-
sented by Frances Richards. C.R. Sim-
coe, “Metallurgy Lane:
The Age of Steel, Parts I
and II,” Adv. Mater. Pro-
cesses, March and April
2014.
2. “Historic Heavy
Hydraulic Presses:
Transitioning from
Ferrous to Non-
ferrous Forgings,” Jon
Tirpak. Forge Maga-
zine, North American
Forging is Advanced
Manufacturing Series:
Parts 1-7. Part 1 avail-
able at www.forgemag.
com/artcles/84311-
north-american-forg-
ing-is-advanced-man-
ufacturing.
3. “Advances in
High-Temperature Mi-
croscopy,” presented
by Rian Dippenaar.
Dominic Phelan, Nicole
Stanford, Rian Dippe-
naar, In Situ Observa-
tions of Widmanstätten
Ferrite Formation in a
Low-Carbon Steel, Mat. Sci. and Eng.:
A, Vol 407, Issues 1-2, p 127-134, Octo-
ber 2005, ISSN 0921-5093, .
org/10.1016/j.msea.2005.07.015.
4. “Quench Embrittlement: History and
Importance in High Carbon Steels,”
presented by George Krauss. G. Krauss,
Steels: Processing, Structure, And Per-
formance, Second Edition, ASM Interna-
tional, 2015.
5. “Widmanstätten Ferrite: From Mete-
orites to Rolling Mills,” presented by
John Jonas. Y. He, et al., “Crystallo-
graphic Relations between Face- and
Body-Centred Cubic Crystals Formed
Under Near-Equilibrium Conditions:
Observations from the Gibeon Mete-
orite,” Acta Mater. , Vol 54, p 1323-1334,
2006; C. Ghosh, C. Aranas Jr., and J.J.
Jonas, “Dynamic Transformation of
Deformed Austenite at Temperatures
above the Ae3,” Prog. Mater. Sci., Vol 82,
p 151-233, 2016.