EDX Introduction to Steel 101

I completed an EDX course Introduction to steel earlier this week, taught by Mark Miodownik. The course is self-paced, and the total time needed to work through the material is around 2-3 hours.

I completed the course in 1 session, you could split up the course into smaller portions, if you can spend 20 minutes at a time.

I think this short course is an OK introduction to steel, and to the EDX technology. The course can be viewed as an enhanced lecture, since at the end of each short segment there is a little interactivity, in the form of some multiple choice questions or interactive graphics.

The material is really simplified, the major take homes are; the importance of steel, that it’s a versatile material, why it is the ultimate engineering material, what sort of things control the properties.

The course is quite short for such a large subject matter, so of course it’s rather simplified. I think in a few areas it is too simplified and might be misleading. An example of my concern would be the explanation of how quenching effects the microstructure, nothing about martensite phase is mentioned, only that quenching “freezes in the structure”. The approach is rather like the simplifications that take place in teaching physics were you find out at each level that everything you were taught to date, so I hope people watching the video would be motivated to study further about steels or metals.

Anyway these people seem happy:

So well done to Mark Miodownik and Tenaris for this innovation.

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Vibranium Metal Prices Hit By Global Slump in Demand

Vibranium prices have slumped as seen by the prices at a recent trade show in London. It’s not known if this drastic collapse in prices is due to the general slow down in the world economy following the economic crisis and resulting miss-allocation of funds, or the result of the “Vibranium Cancer” problem. The Vibranium Cancer incident occurred when a the more stable form of Vibranium came into contact with Captain America’s Shield, and the transformation front started to move through the world. Although global crisis was averted, the incident did show how little is known about this wonder metal, and the associated risks.

Captain America’s Shield Now at Bargain Prices

This seems like bad news for the country of Wakanda where Vibranium ore is mined, and is usually a lucrative export.

Lectures on Bainite – 2007

A blast from 2007 for Harry Bhadeshia fans. These lectures can be found on youtube. Slides can be found here http://www.msm.cam.ac.uk/phase-trans/2007/M/M.html

Prof. Bhadeshia’s new book will be available soon, you can find details here: http://www.oxbowbooks.com/oxbow/other-subjects/materials-science-engineering/bainite-in-steels-3rd-edition.html

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.”

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

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

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

Making a welded Damascus Knife

John Neeman Tools have posted a beautiful video of manufacturing a welded Damascus patterned knife.

5 layers of 3 different steels were forge-welded, folded, and forged. With each step being repeated 8 times. This produces a patterned with 320 layers. Finally twisting and forging the steel produces a more complex pattern.

Just checking the number of layers, I get their total to be different. My calculation of the number of layers is 5 × 2⁸ = 1280, that is 4 times more than claimed (320 layers should be the result of folding 6 times (6 folds 5 × 2⁶).

With 1280 folds, if we assume the thickness of the knife is 2 mm, that means each layer is 1.6 μm, 320 folds would be 6 μm layers. These are both lower than what can be resolved using the naked eye. It’s very close to the wavelength of visble light — if the metal were folded one more time, or the final thickness of the knife is less than 1 mm you would be there.

Effect of tempering upon the tensile properties of a nanostructured bainitic steel

This paper is now available at http://www.sciencedirect.com/science/article/pii/S0921509314009642 for those with access by science direct. I made final proof corrections last Saturday, so when the final version is released the conclusions will change… in that “hard–nanostructured–bainitic steels” will become “hard nanostructured bainitic steels”.