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本帖最后由 Xavier2005 于 2020-5-15 21:17 编辑
以前从谷歌上下载的好文章
Offsetting Shrinkage in Ductile Iron
What Thermal Analysis Shows
By David Sparkman
May 30, 2001
Last Revision February 11th 2006
Abstract
The natural shrinkage that occurs during the solidification of Ductile Iron can be
offset by the expansion caused by the formation of graphite. Though this has
been known for some time, thermal analysis has some interesting contributions
to understanding exactly what is going on, and offers some opportunities for
better control of late graphite expansion in moderate section sizes. Different
modes of solidification are examined and measured, and the early and late
graphite content are calculated using thermal analysis. Carbon flotation is seen
as a fourth form of solidification that is both hypereutectic and hypoeutectic.
Shrinkage is seen as a lack of late graphite growth needed to offset the natural
contraction of the Ferrite. Grain boundary shrinkage can be seen as an escape
mechanism for minor unfulfilled contraction. Stress relief heat treat increases the
graphite volume thereby collapsing any remaining of the grain boundary
shrinkage and improving fatigue life and other physical properties.
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