Royal Societies Inspiring Scientists

The Royal Society put together some student resources on Inspiring British scientists with minority ethnic heritage. My Supervisor Harry Bhadeshia is twice as inspiring as the rest, as you can see from the Royal Societies Tweet:

Royal Soc Inspiring Scientists

Royal Soc Inspiring Scientists

Link to resources

Fabrication of Magnesium diboride superconductor

Bhadesha123 has posted a nice video on youtube discussing the fabrication of Magnesium diboride superconductors.

This seems an interesting metallurgical case study about developing a processing route. Advantages of swagging and drawing are discussed as well as the importance of preventing grain growth to allow processing and for control of material properties.

The video was provided by Professor Bartek Glowaki of the University of Cambridge, who filmed, directed and edited the videos.

Forming carbon from iron

During deformation of austempered ductile iron the carbon can be squeezed out of the material. This carbon is present as nodules of graphite, what is probably happening is that the carbon nodules migrate to the surface, allowing the volume to be reduced in response to the loading.

Another possibility is that carbon is dissolved into the iron and then nucleates and grows sheets on the surface. That seems less likely.

At high temperatures the mostly likely thing to happen would be that carbon on the surface would oxides and form CO gas and be liberated.

Dyanamic test austempered ductile iron

Drs Dawid Myszka, A. Wieczorek and Tadeusz Cybula from the Warsaw University of Technology, Poland investigated the influence of microstructure on the dynamic mechanical properties of austempered ductile iron using Taylor impact testing. Austempered dictile iron means it’s a cast iron, so has graphite particles in a matrix heat treated to become bainite!. Taylor impact testing means you fire cylinders of the material at an immovable object and see how the material gets squished.

Deforming Austempered Ductile Iron

Shattering Austempered Ductile Iron

The heavily deformed volume which faced the impact has resulted in hardening and in transformation to martensite — both hardness and magnetic measurements have been used. Hardening was due to mostly strain induced austenite-to-martensite transformation, and also due to cold-work.

References
D. Myszka, L. Cybula and A. Wievzorek
Influence of heat treatment conditions on microstructure and mechanical properties of austempered ductile iron after dynamic deformation test
Archives of Metallurgy and Materials
V59, Issue 3, 2014

DOI:10.2478/amm-2014-0204

Which is better, iron or gold?

To Croesus, King of Lydia, on being shown his golden treasures, Solon said: “If another comes who hath better iron than you, he will take away your gold.”

1280px-Kroisos_stake_Louvre_G197

Croesus on the pyre*

*image shown depicts King Croesus, unlikely to show Solon.

King Croesus introduces gold coinage (adopted by the Persians after they defeated him) although his coins used a gold-silver alloy (electrum) based on the composition of the alluvial deposits. When he asked the Delphic oracle of Amphiarus if he should wage a campaign against Cyrus the Great of Persia or seek an alliance, the Delphic advice was that if Croesus attacked the Persians, he would destroy a great empire.

Sources

Herodotus, The History of Herodotus, Translated by George Rawlinson

http://classics.mit.edu/Herodotus/history.mb.txt

http://www.thelatinlibrary.com/historians/herod/herodotus2.html

http://www.bartleby.com/344/370.html

Running on Straight Rails

Boffins in Austria have been studying railway tracks to better understand the residual stresses that result from straightening them during processing.

Roller straightening is the final step in production of the rails, after hot rolling is performed at around 1000&degree;C cooling (presumably with water spray) results in curvature of the rails. This varies depending on the rail geometry and cooling conditions.
Untitled

Results from finite element modelling, and measurement of stresses using the contour method and neutron diffraction were compared. The model matches the trends of the measurements in the vertical plane (possibly the mode important since it has the largest residual stresses). In the paper comparison of neutron results for triaxial stresses shows there are residual stresses in the plane perpendicular to the vertical through the rail tool, although these were not predicted by the FEM model.

Residual Stresses

Residual Stresses along vertical symmetry axis

References

  1. http://phys.org/news/2015-01-rails-straight.html#nRlv
  2. R. Kaiser, M. Stefenelli, T. Hatzenbichler, T. Antretter, J. Keckes and B. Buchmayr (2014) “Experimental characterization and modelling of triaxial residual stresses in straightened railway rails,” The Journal of Strain Analysis for Engineering Design, 1-9 DOI: 10.1177/0309324714560040

No Highway in the Sky

‘No Highway’ is a book dramatising fatigue in metals, the story was made into the movie ‘No Highway in the Sky’ staring Jimmy Stewart. This is the only movie I know which is about metal fatigue. The book was published in 1948, and the movie appeared in 1951.

The author Nevil Shute Norway, was a pioneer aircraft designer. The story centres around Theodore Honey, a middle-aged widower and boffin at the Royal Aircraft Establishment Farnborough (site of much fundamental work on aircraft and fatigue).

Theodore is sent to investigate a previous air crash, but he realises that his theory applies to the plane he is travelling on, which he forces to land. After inspection of the aircraft on land, the much annoyed pilot is ready to take-off again, leaving Theodore Honey behind. However, Theodore’s conviction in his theory leads him to ground the plane by retracting the landing-gear. Everyone is left perplexed by his actions, except the air-stewardess and an actress aboard the plane who Theodore had convinced.

Therefore, go forth, companion: when you find
No Highway more, no track, all being blind,
The way to go shall glimmer in the mind.

Interestingly the book, in which a new airliner design being subject to mechanical failure due to metal fatigue, came before the failures of the de Havilland Comet airliner just six years later (1954).

James Stewart in No Highway in the Sky

James Stewart in No Highway in the Sky

As well as the book “No Highway” and the movie, there is also the radio play made by CBS. The radio play also stars Jimmy Stewart and Marlene Dietrich.

Part 1

Part 2

Part 3

Part 4

Part 5

Part 6