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.
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)
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

Why does my Stainless Steel Knife Corrode?

My metallurgist colleague was very disappointed in this knife because she believed that stainless steel wouldn’t corrode. Unfortunately if left in still water oxidation pitting will occur in all stainless steels. My colleague was very surprised to get corrosion in this knife because it is usually hand washed and then just left with a little water on it, similar to other utensils, but after six months it had started to rust. The corrosion may be the result of the relatively high carbon content in the knife, which means it is likely to form carbide particles which act to sensitise the steel.

X50CrMoV15 is a German standard with around 0.5 wt% carbon (percentage by weight) and total around 15 wt% chromium, molybdenum and vanadium. This is regarded as being highly stain resistant. Usually a steel is regarded as stainless it is possible to maintain a chromium level above 12 wt% at the surface, since this has been found to form a stable oxide layer.

C Si Mn P S Cr Mo V
0.45 – 0.55 max 1 max 1 max 0.04 max 0.015 14 – 15 0.5 – 0.8 0.1 – 0.2

Z-knives have previously found that rusting occurred on X50CrMoV15 as a result of using dishwasher on otherwise unused knife.





`Japanese' Cooks Knife

`Japanese’ Cooks Knife

New York Times announcement regarding the discovery of stainless steel.

New York Times announcement regarding the discovery of stainless steel.

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.


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

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Subscibe to RSS Feed for posts I remember to add to Podcasts category

DeLorean manufacture to resume

This iconic car is well remembered because of it’s appearance in the Back to the Future movies. Now there are plans to build a small number of the cars. The DeLoreans will be built in a suburb of Houston, Texas, where Liverpool born Stephen Wynne has a 3,700 sq m warehouse chock-full of DeLorean car parts, which were sold by the liquidators when the company flamed out after less than two years of production. Until now Mr Wynne has been using the spare parts to maintain the 9000 cars that were originally built during the two years of production.

The car was made with a stainless steel body, this saved on capital costs since no paint baking line was needed. Possibly a better solution than Henry ford making all of his Model-T cars black because the paint dried faster.

Picture from Wikipedia DeLorean DMC-12 article

The Gaurdian business supplement had a story in August covering the plans to resume production: Back to the Present for DeLorean.

The UK government originally invested £78 million UKP to attract production of the DeLorean to Northern Ireland. That works out as a subsidy of £8667 UKP per car. Margret Thatcher became Prime Minister in 1979 and was a person who took a dim view of government subsidy of industry. However the cars were to be built in a employment black spot, and Nothern Ireland was a hot political issue.

John DeLorean was arrested suspected of Drug Trafficking in 1982 by the FBI but was found not guilty in of the charges in 1984 after using a defense based on Entrapment – the accusation was that the money from trafficking was meant to bail out the ailing company.

The new DeLorean company plans to make around 25 cars per year. With basic price of $58000 USD.