Benjamin Huntsman - Crucible Steel Process

Until 1742, producing steel was a difficult task. The quality of the steel was often unreliable. The steel was made by heating iron bars which were covered in charcoal. The heating was continued for up to a week. The material produced was called blister steel.

Blister steel was then turned into shear steel by wrapping blister steel bars up in a bundle and then heating them again before forging the bundle. The heat and the action of the forge hammer welded the rods together as they were hammered to the size required. This shear steel was used to make razors, files, knives, swords and the other steel items for which Sheffield became famous.

No more than about 200 tons of steel were produced each year in Sheffield, using this process.

Benjamin Huntsman's crucible steel process changed all that. He was the first person to cast steel ingots. The process produced uniform high quality steel in reasonably large quantities,

M. Le Play, Professor of Metallurgy at the Royal School of Mines of France, wrote in 1846 that Huntsman's memorable discovery advanced the steel manufactures of Sheffield to the first rank, and powerfully contributed to the establishment of the industrial and commercial supremacy of Great Britain.

Within 100 years of the invention of the process, Sheffield was producing 20000 tons of crucible steel a year. This was 40% of the total amount of steel produced in Europe at this time.

Benjamin Huntsman

Benjamin Huntsman was born in Lincolnshire, England in 1704. His parents had moved here from Germany shortly before his birth.

As a boy, Benjamin showed a flair for mechanical crafts. As a young man, he set up a clock-making business in Doncaster (about 20 miles north of Sheffield). He also practiced as a surgeon and oculist as well as carrying out general mechanical repairs.

Like most of the people who manufactured steel products, he obtained his steel from Germany. Unfortunately, he found that this material was not suitable for the springs and pendulums of the clocks which he was making. He began experiments to produce a better quality of steel but had difficulty in obtaining suitable fuel for his steel making furnace.

In 1740, he moved to Sheffield where there was a better supply of the coke he needed as a fuel. He first settled in the district of Handsworth just to the south of the centre of Sheffield where he carried out his experiments in secret.

After many years of experimenting, he finally perfected his crucible steel process and realized that this process could be used to make superior tools and cutlery. When he tried to interest the local cutlers in using his steel for their products, he had little success. The Sheffield cutlery manufacturers refused to buy it, on the ground that it was too hard, and for a long time Huntsman exported his whole output to France.

The growing competition of imported French cutlery made from Huntsman's cast steel at length alarmed the Sheffield cutlers, who, after vainly endeavoring to get the exportation of the steel prohibited by the British government, were compelled in self defense to use it.

Huntsman had not patented his process. Many attempts were made by rival businesses to discover Huntsman's secret process. One story about these attempts involves an iron founder called Walker who had a foundry at Grenoside, on the northern outskirts of Sheffield. It has been written that Walker disguised himself as a tramp and arrived outside Huntsman's works pretending to be ill. It was a very cold night and snow was falling. Walker pleaded with the workers to let him in so that he could warm himself. The workmen allowed the beggar to take shelter and sleep in a corner of the workshop. Whilst he pretended to sleep. Walker watched all the operations of the crucible steel process. He discovered that part of the secret was in the flux. He saw the workmen break up some old green bottles which were then put in the crucibles on top of the steel. About three months after this cold night, it is claimed that Walker's foundry in Grenoside was also making crucible steel.

The demand for Huntsman's steel increased rapidly and in 1770, he moved his factory to a new site in Attercliffe in the Don Valley. This area later became the main location for the huge special-steel making industry of Sheffield.

The Royal Society wanted to enroll Huntsman as a member in recognition of the merit of his invention of the crucible steel process. Benjamin turned down this honor because he felt that it would conflict with his desire to work in seclusion and would also be against his principles as a member of the Society of Friends (Quakers).

Benjamin Huntsman died in 1776 at the age of 72 years. He was buried in the local churchyard in Attercliffe. His steel making business was carried on by his son William Huntsman (1733-1809), who increased its business on its reputation for producing the best cast steel that is made.

At Sheffields Northern General Hospital one of the original main buildings is named after him, and in the city center is a Wetherspoons pub called "The Benjamin Huntsman"

Metal sculpture at Meadowhall

There's a plate down there about Benjamin Huntsman; not sure if he designed it or if it's dedicated to him. He was a clock maker.

Norfolk Arms, Handsworth

One of the old pubs in the area, the Norfolk Arms is identified on the 1901 OS map. Just down the road from here, Benjamin Huntsman, inventor of crucible steel lived for a while in 1742,

The Crucible Steel Process

Dating from 1829, the crucible furnace at Abbeydale is the world's oldest example of the type developed by Benjamin Huntsman.

The crucible steel process starts with the manufacture of special clay pots or crucibles. These are about 50cm tall and about 20 cm wide. Each one can hold about 20 kilograms of steel.

The crucibles are heated in a coke fired furnace set in the floor of the furnace shop. When they are at white heat, they are filled with broken bars of steel and a flux to collect impurities. A lid is then placed over the pot and the furnace is charged with more coke.

The steel is then melted for about three hours. The furnace operator keeps adding more coke and checks the melting steel at the same time. To start with, the steel bubbles as it melts. Eventually the bubbling stops and the surface of the melt become clear. The steel is now ready for teeming.

Lifting the crucible out of the furnace

The pot is lifted out of the furnace using long handled tongs which grip round the outside of the crucible. The pot is then stood on the furnace room floor and picked up using another set of tongs which fit round the middle of the crucible.

Teeming the molten steel into an ingot mould

The molten steel is then poured from the crucible into a cast iron ingot mould. When the steel has solidified and cooled, the mould is opened so that the steel bar can be removed

After the steel has been poured, the crucible is replaced in the furnace and another charge of raw steel is added for melting. Most of the crucibles can be re used for three melts before becoming too weak, when they are thrown away.

Temperatures in the crucible furnace reached 1600°C and the strength of the 'puller out', who lifted the weight of molten steel from the furnace was legendary. The 'teemer' was also a highly skilled worker, carefully pouring the steel into ingot moulds with strength and precision.

Another form of crucible steel was developed in 1837 by the Russian engineer, Pavel Anosov. His technique relied less on the heating and cooling, and more on the quenching process of rapidly cooling the molten steel when the right crystal structure had formed within. He called his steel bulat; its secret died with him. In the United States crucible steel was pioneered by William Metcalf.

Crucible steels remained the world's best, although very expensive, for some time. The introduction of the Bessemer process and other steelmaking processes gradually replaced it, being able to produce steel of similar (or better) quality on a much larger scale more quickly and cheaply. The Bessemer process and more modern methods differ from crucible steel production in that they remove carbon from the pig iron, but stopping before all the carbon is removed, whereas the ultimate raw material for tradition crucible steel was wrought iron, to which carbon had been added by cementation.

Crucible steel did not disappear when the Bessemer process was introduced. Cast steel is still the preferred method for specialty steel production, especially tool steel. While more expensive than the Bessemer and other later methods of steel production, it is still among the most precise. So rather than disappearing it became a niche market.

Sourced from Wikipedia and tilthammer.com