The Kent R. van Horn Lectureship is an endowed Lectureship at the Case Western Reserve University and dates from 1974. It honours Kent R. van Horn, an alum, who had a distinguished career as a metallurgist, director of research, and ultimately corporate vice-president of Alcoa. Three lectures on varied topics are to be delivered over three successive days. The 2015 lectures were delivered by Professor Harry Bhadeshia. This one is on the first bulk nanostructured steel.
These videos are reproduced courtesy of the Materials Science and Engineering Department of Case Western Reserve University.
http://engineering.case.edu/emse/node/121
http://www.msm.cam.ac.uk/phase-trans
Abstract: This is a story about a most elegant structure
created in steel, consisting of incredibly fine and
slender crystals of ferrite permeating a matrix of
austenite. The crystals are typically 20–40 nm in
thickness and in the form of plates. There are so
many of these crystals per unit of volume, that a
material is created which has one of the highest
density of interfaces known to man.
And all this can be achieved in samples which are
large in all three dimensions, without the use of
deformation or rapid heat treatment, and at a cost
which in terms of weight or volume compares with
that of bottled–water. There is no new
manufacturing technology required, the fabrication
of the steel is conventional. But the heat–treatment
is far from conventional, involving periods of up to
ten days at temperatures in the vicinity of 200◦C.
The end result is a hardness in excess of 700 HV,
strength of the order of 2.5 GPa, uniform ductility
in the range 7-27%, and toughness in the range 30–
50 MPa m^{1/2}.
The choreography of atoms during the
transformation of austenite into the crystals of
bainitic–ferrite has a major role in determining the
structure. I will describe how the material was
discovered and the underlying phase
transformations theory. Hundreds of tonnes of the
material has been produced and utilised in a variety
of specialised engineering applications such as
shafts and armour. The new science associated with
this material, including a remarkable new Fe-C
phase diagram, is described.
