When strong steels become tired – fatigue

Not a subject to get tired of…

Prof Harry Bhadeshia gave a seminar at KTH, discussing fatigue of steels. Fatigue performance is critical for many applications. In this talk we can hear about mechanisms of fatigue, and how we can design against fatigue failure. Particular attention is paid to steels for use as rails, bearings and shafts, applications were Giga-Pascal-strengths are required in bulk.

Here we can see the Seminar and discussion:

Steel Science 2017 online

International Symposium on Steel Science

Characterization and design of multiscale heterostructures in advanced steels.


Materials with 1bn times the strength of steel?



Because of the immense gravity of neutron stars, the outer layers freeze solid to form a crust that surrounds a liquid core. Between the outer layer and the inner core quark–gluon plasma (or quark soup) nuclear pasta forms at matter densities of 10^14 g/cm^3. Protons and neutrons are thought to spatially separate as nuclear attraction and Colombic repulsion forces compete (a type of Spinodal decomposition) and end up forming long cylindrical shapes or flat planes. These have become known as “spaghetti” and “lasagne”—or nuclear pasta.

In a recent PRL paper, it was claimed that this nuclear pasta has a stength of 10 billion times that of steel.

The paper states in abstract a strength of 10^30 ergs/cm^3. 1 erg / cm^3 is equivalent to 0.1 J/m^3. 0.1 J/m^3 is the same as 0.1 Pa. Therefore 10^30 ergs/cm^3 is 10^29 Pa.

Comparing this to the 5.5 GPa stength of Steel Scifer wires… ultimate shear strength = 0.5 * UTS = 2.25 GPa.
(A value for maximum theoretical Shear strength would be 12 GPa I believe).

So now …. 10^29 Pa / 2.25^9 Pa = 3.0 x 10^19 * steel strength = 30.25 Quintillion times the strength of steel.

Tell me what I’m missing here… maybe the paper converted to specific strength over exaggerate their value? What’s the density of nuclear pasta?

mtex examples with data

I have been doing a bit of play using mtex to look at some EBSD data which I previous exported to .ctf format. mtex is an open source (GPL) software, which written for the commercial matlab software. The mtex package comes along with several examples and tutorials which can be read within matlab or over the http-internet-web.

Example scripts for using mtex are also available to download from the recently published paper “On Three-Dimensional Misorientation Spaces” by Krakow etal. published in Proceedings of the Royal Society A, 473, 2017.

Scripts and EBSD data for the case studies in the paper are available here:


Scripts for producing other figures in the paper (explaining orientation relations etc.) are available from the mtex website here (along with other examples):


Screenshot from 2018-06-11 19-56-55

Welsh steel Inquiry


Can hear information about costs of running a steel plant, market information.

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.

Are we living in the Steel age?

I think that in the future this age will be recognised as the steel age (or bainite age!), future historians will probably still over look the vital role of steel in their own civilisation (although no doubt it will still be of vital importance if they are civilised). However, with the benefit of hindsight they will probably be able to recognise it’s importance during this era. In a dystopian future they will tell camp-fire stories about the ancients and their hidden steel knowledge, and their ability to make ‘things’.

Probably Stone and Bronze age peoples didn’t recognise they where living in an age defined by the materials they used, either. That’s because they used many other materials too, and concerned themselves with where the next meal was coming from, and generally got caught up in the drama of Bronze age existence.

Steel in action, in the modern city of Vancouver.

Steel in action, in the modern city of Vancouver.