Soldier's helmet made of Hadfield's manganese steel, 1882-1884.
© Science Museum / Science & Society Picture Library
Sir Robert Hadfield (1858-1940) invented manganese steel in 1882, and it was the first malleable, non-magnetic, ferrous product. It becomes harder and stiffer when worked cold so is very resistant to wear and abrasion. Manganese steel was used for soldier's helmets in World War I, and this example which has been tested under impact, demonstrates its stiffnes.