Some products in the world of iron and steel are so useful, they deserve special mention, one of which is manganese steel. Manganese steel typically has between 11-14% manganese content and a relatively high carbon content averaging around 1.2%. The chemical properties mean that it has high toughness and ductility so that when in service it can undergo repeated impact or abrasion which only serves to work-harden the steel.
A steel which work-hardens under abrasion could be a highly sought after product, except for the problems it creates during cutting and machining. Such a resistant product is virtually impossible to process using conventional means, instead relying on plasma arc or laser cutting. This effectively limits its range of usefulness as the difficulties in developing into a final product rule out lower end functions.
For the number geeks, the hardness of supply condition manganese steel is around 200HB with a tensile strength of 880N/mm2. The steel keeps up its solid interior when work-hardened; examples of work-hardened austenitic manganese steel have increased up to hardnesses of 500N/mm2.
The steel itself is remarkable considering its origins are in the late 19th Century. Developed and discovered by Sir Robert Hadfield, he lent his name to it and, as one of the first alloyed steels in 1882, it was known as Hadfield steel.
Sir Robert himself believed greatly in iron and steel technological advancement. His metallurgical research began when he took over his father’s business in 1888 and building it up in the Hadfield Steel Foundry, it went onto be one of the biggest steel foundries in the world. Leading from the top, Hadfield worked to develop silicon and alloy steel grades, publishing his findings and forging forth in his field. His keen knowledge, as well the discovery of manganese and silicon steel saw him knighted in 1908, becoming a fellow of the Royal Society a year later.
It’s possibly no coincidence that this was after manganese steel’s first roaring success when used as part of the Sheffield Tramway in Fitzalan Square. Hadfield’s steel lasted for 12 years with approximately 13.5 million tramcars passing over it. The previous carbon steel construction had worn out and failed after just 12 weeks!
Edgar Allen & Co, another Sheffield based firm, used manganese steel in a series of complicated railway track developments, as well as flat and round bar for security as prison bars. When used on Hadfield Steel, the prisoner’s hacksaw proved to be as much use as the cake it was smuggled in.
While manganese steel was a marvel of its age, it still has uses today in elevators, anti-drill security plates, shot blast cabinets, scrapers and screens. Its most common form is in sheet and plate, normally under 20mm thick, although for more extreme uses, 40mm can be found. It still has modern specifications and equivalencies, with Werkstoff X120Mn12, Euronorm X120Mn13 and ASTM A128. It could be said that for his dedication to his craft, however, we should still use the moniker after the man and make reference to Hadfield Steel.
Photo Credit: Britannica