In earthmoving equipment, a combination of hardness and toughness is often required. This is
achieved by alloying steels with manganese. Hadfield or manganese steels are very hard on the
surface (martensite) and soft inside (austenite).
5.13.7 Ways to Harden Steel
Three main ways to harden steel are:
g introduction of alloying elements
(Figure 5.36)
g mechanical deformation (cold work)
g heat treatments
1) Alloying Elements
The introduction of alloying elements to the crystalline
patterns (such as BCC or FCC) will deform the pattern
and harden the metal. Carbon is one of the main alloying
elements because it is cheap and has a tremendous
impact on hardness and strength. Carbon has a dual
effect on steel, as it fixes the maximum attainable
hardness and contributes substantially to determine the
hardenability.
Several other alloying elements are manganese (Mn),
silicon (Si), chromium (Cr), and nickel (Ni). The most
important function of these elements, in heat treatable
steels, is to increase hardenability, making the hardening
of large sections possible while using moderate quenching
methods.