||Most steel needed to be shaped (machined) before it could be used. This was achieved by casting the steel in a mould. To cut the steel into more precise shapes tool makers or machinists had two options :-
They could either soften (anneal) the metal before cutting it or they could harden the steel tool which was to do the cutting. In the early nineteenth century the second option was preferred the tool was heated and then the end was plunged into water (quenching). This hardened the steel but the procedure often resulted in the cracking of the head.
A solution to this problem was found by Robert Forester Mushet (son of the famous Scottish iron master, David Mushet). He was working as an iron-master in the Forest of Dean in Gloucestershire carrying out experiments to improve the quality of manufactured steel.
In 1856 he had perfected the Bessemer-Mushet process of manufacturing cheap steel. This was achieved by adding spiegeleisen to the blown metal during the melting process.
By 1868 Mushet had discovered that by adding a small amount of tungsten to the crucible melt a new steel was formed that had remarkable qualities. Tools made from this steel required no quenching, the steel was hardened in the open air. This tougher steel could now cut harder metals and at faster speeds than the old carbon steel types and they had five or six times the normal length of life.
Mushet described it as self-hardening steel which soon became known as Robert Mushet's Special Steel (R.M.S.). The product was the first real tool steel and the forerunner of modern high-speed steels.
Mushet did not want to risk sharing his discovery with his rivals and decided against taking out a patent. He made a deal with a local steelmaking firm in Gloucestershire (the Titantic Steel & Co.) who were to be responsible for selling the steel. In 1871 the company had to be closed down and Mushet entered a new agreement with Samuel Osborn a Sheffield steelmaker.
Robert Woodward, the secretary of the Titanic Works had introduced Mushet to Osborn in 1870, when Osborn was visiting Cheltenham looking for sales of his tools. The agreement was straightforward, Osborn was given the sole right to manufacture R.M.S. and Mushet was to receive a royalty on every ton sold.
To ensure secrecy some of the specialised processes were still carried out in the Forest of Dean overseen by Mushet himself. Elaborate precautions were taken when transferring the materials from the Forest Steel Works to Sheffield. Only a few men worked at this site and they never talked about their work. Once in Sheffield Mushet's sons, (Henry and Edward) were given the task of supervising the final processes, some of which were were done off-the-premises once again in secrecy.
He was awarded the Bessemer Gold Medal in 1876.
Robert never visited Sheffield himself, although he kept in close contact with Samuel Osborn.
Robert Mushet died in January 1891.