Steels for quenching and tempering are divided into: non-alloy steels and alloy steels; they have the best compromise between mechanical strength and toughness. They are mainly used for mechanical components, for which good impact and vibration resistance properties are required (for example, connecting rods, pins, shafts, levers, etc.).

We could say that the percentage of carbon varies between 0.21% and 0.60%.

There are many steel grades available on the market with only carbon content (eg. C45E-R) or with alloy elements in variable percentage (Ni, Cr, Mo, Mn);

Alloy elements have the following functions:

• Nickel: promotes toughness and hardenability;
• Chrome: favours hardenability;
• Molybdenum: works against the development of fragility when tempering;
• Manganese: improves hardenability;
• Vanadium: refines the crystalline grain.

These steels are usually tempered in water or oil at about 620 °C.

Examples of non-alloy steels for quenching and tempering: C35E, C35R, C40E, C40R, C45E, C45R

Examples of alloy steels for quenching and tempering: 42CrMo4, 25CrMoS4

Hot rolled material is purchased according to EN ISO 683-3 whereas cold drawn material is sold according to EN 10277: 2018