Hadfield vs Hatfield

I always get these two Sheffield related names mixed up.

Hadfield Hatfield
Sir Robert Abbott, Baronet Hadfield Dr. William Hatfield
Inventor/ manufacturer of high Mn
steels known as Hadfield Steel
Inventor in 1924 of 18/8 stainless steel, and 321 stainless steel (18Cr-8-Ni+Ti).
1858-1940, Born in Sheffield, Died in Surrey 1882-1943, Born in Sheffield.
Knighted
Son of Robert Hadfield
Wrote over 200 Papers Authored many papers.
Made Hadfields foundry one of largest in World Appointed director of Brown-Firth Research Laboratories (succeeding Harry Brearley)
FRS FRS
Hadfield steel can also refer to some high silicon steels  Stainless Steels and also some high temperature alloys were developed by Hatfield (12Ni-5Mn-4Cr which has high thermal expansion coefficient and 5Ni-4Cr-3Mo which has strength at high temperature).
Obituary Obituary
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Adventures in Physical Metallurgy of Steels

During July 2013 I attended Adventures in Physical Metallurgy of Steels hosted by the Phase Transformations and Complex Properties research group of the Department of Materials Science and Metallurgy.

The programme looked like this, videos are appearing on bhadeshia123’s channel on youtube (links). There is also a playlist available.

Programme
Introduction to Adventure. H. Bhadeshia

Architectured Steels, T. Koseki

Magneto-structural coupling. I. Abrikosov

Quench and partitioning. J. Speer

Crystallographic variant selection. S. Kundu

Secondary hardened bainite, J. R. Yang

Welding of high carbon steel, K. Fang

Isotropy and Fatigue: P. Ölund

Atoms in bainite, atomic mechanisms. F. Caballero

Pulsed steels, R. Qin

Fullerenes & buckyballs in steel: I. V. Shchetinin

Boron: Type IV cracking, F. Abe

Low-density steel, H-L. Yi

Friction stirring of steel, T. Debroy

Flash Processing, G. Cola

Reliable first principles calculations for iron: A. Paxton

Steels composites for energy applications, C. Capdevila-Montes

Microstructures without contact, C. Davis

Pop-in deformation, H. N. Han

Plausibility of fine bainite, C. García-Mateo

Reduced Activation, K. Wu

Architectured microstructures, G. Anand

Flash microstructure, S. Babu

Energetic TWIP, D. Dye

Mass production of fine bainite: A. Rose

Voids and 30000 atoms, S. Munetoh

Soft Particles, T. Tsuchiyama

Mechanochemistry, F. Miani

Simplex and Kappa steels, I. Gutierrez-Urrutia

Innoculated high-speed steel, A. Chaus

Non-cubic ferrite, D-W. Suh

Montage of events

Superbainite

Structure of superbainite. Inset is a same-scale image of a carbon nanotube. [1]

Structure of superbainite. Inset is a same-scale image of a carbon nanotube. [1]

According to archaeologists, the Iron Age began in 1300 BC and lasted for around two millennia. Today, steels (alloys of iron and carbon) comprise 95% of global metal consumption and this trend shows no sign of declining.

Glancing at the media, however, one would be forgiven for assuming that steel is now a has-been. We are bombarded with stories of novel materials: carbon nanotubes, metallic glasses, graphene, carbon fibre, nickel superalloys. . . all of which are “stronger than steel”.

“Now we can construct space elevators!” claim the articles. “Let’s build a climbing frame to the moon! We’ll use this stuff to make everything!”

The observant among us, however, will note that most cars, trains and buildings still don’t feature superalloys, metallic glass or magic nanotubes. Neither are they invisible; nor do they fly; nor do they do any of the other things that journalists tend to ‘predict’.

Instead, steels somehow remain the best — and cheapest — materials for the job. Also, they are stronger than steel. This is because ‘steel’ is a vague construct used by sensationalists, with an unspecified strength guaranteed to be less than that of a novel material. Metallurgists rarely refer to ‘steel’, just as the Inuit have fifty words for snow, not one of which is ‘snow’.

Continue reading

Breaking the Glass Ceiling Since 3000 BC

Archaeologists in Austria have found evidence that women were metalworkers during the Bronze Age:

The Museum of Ancient History says the grave originates from the Bronze Age, which began more than 5,000 years ago and ended 3,200 years ago.

In a statement on Wednesday, it said that although the pelvic bones were missing, examination of the skull and lower jaw bone shows the skeleton is of a woman.

The museum says tools used to make metal ornaments were also found in the grave northwest of Vienna, leading to the conclusion that it was that of a female fine metal worker.

It says such work had been commonly presumed to be in the male domain.

Perhaps discoveries like this will challenge conventional ideas about the division of labour in ancient societies. Metallurgy and metalworking have been male-dominated subjects for virtually all of time, so it’s interesting to see that women were still involved even at the earlier points in its history. This woman was identified as a metalsmith thanks to the grave goods that were buried with her: an anvil, hammers, flint chisels and some dress jewellery. In fact, it makes a lot of sense that Bronze Age women could be metalworkers. Materials like copper and tin* can be melted by a kiln without needing to pump a lot of excess air to feed the fire. Contrast this with ironworking, which requires a great deal of physical strength to pump air into the fire, and to shape the iron by hammering at arms’ length. When we think about smithing, the picture that comes to mind is a burly blacksmith in a forge, hammering away at a sword. Yet bronze was frequently used to manufacture household items like knives, needles, pins, mirrors, jugs, pots and cauldrons. Women were known to be exceptionally skilled potters. The question is: were they as good with metal as they were with clay, or did pot-making suddenly become mens’ work? Bronze is not particularly difficult to cast or grind and much of the early labour that is classed as womens’ work (cooking, pottery, childrearing, gathering unaccountably pink berries) involved a lot of working with fires and moderate physical activity. If a woman can grind corn, she can grind bronze.

Maybe women were also involved in the discovery of new metals and techniques. Gold was the first metal to be discovered and worked by humans, and early goldsmiths would collect gold nuggets from stream beds. If women did take on the role of gatherer in their societies, it could well have been a woman who found the first gold nugget, while collecting water from a stream or gathering fruit nearby. Meanwhile, archaeologists believe that copper smelting first took place inside pottery kilns (since campfires are not quite hot enough) – another domain of women. Tin and lead are more easily smelted, and this discovery was probably accidental, involving either a campfire or a cooking fire.

There is currently no way to know for sure whether this woman was an outlier even in her time, or whether Bronze Age societies routinely had female as well as male metalworkers. Some iconography does seem to imply that there was a division of labour according to sex but this is only a tiny snapshot of life at the time, and gender-specific artefacts are rare. Much archaeological excavation tends to focus on domestic locations within settlements, whereas typically ‘male’ activities like hunting and metallurgy would have taken place in other areas, so evidence of these practices is less likely to enter the archaeological record. The preconceptions of archaeologists must also be taken into account. It would be interesting to see how often a woman’s skeleton has been excavated, revealing that she was buried with weapons or tools, and the explanation provided was that the burial goods were purely decorative, and unrelated to the woman’s actual occupation. The issue of gender bias in archaeology is not a new problem, and only in the past few decades have archaeologists begun to recognise that this needs to be corrected, by becoming aware of their own inbuilt preconceptions and how these preconceptions might affect their interpretations of ancient life.

*Fun fact: the earliest bronzes were actually alloys of copper and arsenic. Tin came along much later. Unfortunately, the fumes created during the manufacture of arsenical bronze have some unpleasant side effects, one of which is permanent nerve damage. Some people have speculated that this is where the myths of Hephaestus – the lame Smith of the Gods – came from.

Niobium and Columbium

Columbium is an alternative name for Niobium. In steels niobium is a common microalloying element, that is added in small which then have a large influence on the resulting mechanical properties.

Strong carbide formers can be used for microalloying to form small precipitates, that is vanadium, niobium, titanium, often used in combination. These elements combine with carbon and nitrogen to make carbides. nitrides and carbonitrides. Vanadium and niobium carbides and nitrides can easily combine together, this may be bacause they have the same crystal structure and similar lattice paramaters.

Looking through some literature recently I was surprised to find a paper on microalloying which had used both niobium and columbium, in different amounts. The paper has 5 authors and is published in Scripta Materialia Influence of short austenitising times on the fracture behaviour or a microalloyed automotive spring steel by Wise, Spice, Davidson, Heitmann and Krauss. Scripta Materialia, 44, 2001, 299-304.

New Podcasts

I made three new podcasts with Prof. Harry Bhadeshia on his latest papers on transformation texture, the new delta-Trip steels and on prediction of Hot Strength of ferritic steels.

The work on transformation texture is from Saurabh Kundu’s thesis were Patel and Cohen’s model has been shown to correctly predict the orientation relationship between ferrite and austenite after martensitic transformation. It’s shown that variants are selected by free energy differences that can be calculated depending on the orientation.

The delta-Trip steels were developed as a result of the prediction of neural networks, were after the neural network was made computer optimisation was used to try and maximise the mechanical properties. This work was done with Saurabh Chatterjee in collaboration with Murugananth Marimuthu. Both Saurabh Kundu and Saurabh Chatterjee completed their PhD’s at Cambridge while visiting from Tata Steel, Murugananth Marimuthu is a previous member of the phase transformations group, and has now also joined Tata Steel’s research and development section.

The work on Hot Strength of ferritic steels is the part of Radu Dmitriu’s topic of research. A neural network model of the hot-strength of ferritic steels. It was observed from the neural network that the strength is expected to suddenly start to decrease at 800 Kelvin, which can has been explained to be due to changes in the mobility of dislocations.

Addendum

According to wordpress documentation these links should get added to the rss feed of this bainite blog as enclosures.

Podcast: Hot Strength

Podcast: Delta Ferrite

Podcast: Transformation Texture

Subcribing to RSS Feed of this webpage should get you all the podcasts, or for Podcasts Only
Subscibe to RSS Feed for posts I remember to add to Podcasts category

UK gold reserves fail to meet gold standard

“This is not about purity, this is about physical appearance,” Says a spokesman for the Bank of England. Mervyn King was not risking making the statement himself.

It has been discovered that some of the bars of gold held in the bank of England have been poorly made and have started to show cracks. The gold showing signs of deterioration was originally imported from America in the 1930s and 1940s falls below the proper LGD(London Goods Delivery) standard as specified by the London Bullion Market Association. The Bars are reported to have the proper assay markings added at the time of manufacture to assure the purity, however the paper work is unavailable.

Gold Ingots
Picture from Wikipedia article about Gold

The bank currently holds a reserve of 320 tonne on behalf of the treasury and they say this could temporarily reduce the value, the gold may have to be re-refined. The gold held by the Bank of England is an insurance policy in case of turmoil in the world’s money markets and the reserve is currently worth around £4 billion. However much of the reserves have been halved in recent years according to government policy lead by Gordon Brown to diversify the holdings.

Revelations about its physical deterioration were secured by the trade journal Metal Bulletin. It’s suggested that pure gold should not crack or exhibit fissures and that therefore the gold may not be 100% pure.

Peter Ryan, an analyst at the consultant Gold Field Mineral Services, said: “I would guess that it would only be a small proportion that doesn’t conform to standards and it would only be an issue if they needed to sell the gold. Some of this gold was acquired 30 or 40 years ago and standards do vary, but it is not difficult to fix.” The gold price has been soaring recently as investors seek a hedge against the falling dollar and inflation worries. Strong demand from India, the biggest gold-consuming country in the world, has also boosted prices. There, gold jewellery, ingots and coins are a favourite wedding and festival gift.

Quoted from Times online article covering this story; All that glisters may not be gold.