Hadfield steel - steel (11-14, 5% Mn, 0, 9-1, 3% C) with high resistance to wear (abrasion) at high pressures or shock loads, it is also characterized by high ductility.
Proposed in 1882 by the English metallurgist Robert Hadfield.
Hadfield steel hardens strongly under shock loads. It is used to manufacture tracks for caterpillars of tanks, tractors, cars, crusher jaws, rail crosses, switches operating under shock loads and abrasion, as well as window bars in prisons.
By the way, the use of Hadfield steel for the manufacture of bars in prisons was, perhaps, the most derisive technique against prisoners. Even having a saw for metal, it is impossible to saw through such a grid, since during the cutting process there is a strong work hardening of the treated surface, and as a result - hardening, an increase in hardness to the hardness of the saw cutting it and higher. This factor makes it impossible to saw through the grating made of Hadfield steel.