Case-hardening steel

Technical data sheets for case-hardening steel grades


Case-hardening steels take their name from the surface treatment given to the parts made from this type of steel, i.e. carburizing. Carburizing is a heat treatment process in which steel absorbs carbon (from 0.80 to 2.00 mm maximum). By once more hardening and stress-relieving the steel, we can obtain a highly durable surface  and a core  which is less hard yet tough. There are different types of case hardening steels they have different chemical compositions.  . However, they allhave one thing in common: these steels have a  relatively low carbon content, which does not exceed 0.20%. When manufacturing thin working parts. only carbon steel can be used, such as C10 and C15. But on larger parts, chromium alloy steels are needed, such as 16MnCr5, 20MnCr5, which have a greater hardenability. If the dimensions are even greater and/or greater hardenability is required, it is necessary to use steels which, in addition to chromium, also contain nickel and molybdenum, such as16NiCr11 and 17CrNiMo6-4. Long rolled products in case-hardened steel are standardized in Europe by the EN ISO 683-3 standard, while cold finished products by EN 10277.


The carburising process makes case-hardening steel suitable for the construction of working parts with a  high wear resistance. By applying the carburizing treatment, followed by martensitic hardening and stress relief tempering, we obtain mechanical parts with an extremely hard surface. We therefore obtain a hard surface layer and a softer, more resistant and tenacious core. These are mainly used in the construction of mechanical parts such as gearboxes and gears. The carburizing treatment is always followed by a single or double hardening. Hardening is considered optimal, especially if the steels  tend to increase their grain. We must bear in mind that the lower the concentration of alloying elements, the less we can control the case-hardening depth and surface hardness of the steel. The carburizing treatment can vary considerably based on the product’s chemical characteristics.

Application sectors

Case-hardening steels are mainly used for steel gears, as the carburising process makes the surface

extremely hard and wear resistant.

The pieces produced are therefore gears, reducers, pinions, camshafts

Product range

DINEN / UNIStandardProcessing routesSupply statusRounds (mm)Squares (mm)Flats (mm)Steel blooms (mm)
16MnCr51.7131EN 10084RolledSoft annealed20-78   
16MnCr51.7131EN 10084Rolled + peeledSoft annealed20-48   
20MnCr51.7147EN 10084RolledSoft annealed30-260   
20MnCr51.7147EN 10084Rolled + peeledSoft annealed22-60   
16CrNi4 UNI 7846 / EN 10084RolledSoft annealed18-320   
16CrNi41.5714UNI 7846 / EN 10084Rolled + peeledSoft annealed20-60   
16CrNi4Pb UNI 7846RolledSoft annealed19-135   
16CrNi4Pb UNI 7846Cold drawnSoft annealed8,30-22   
16NiCr11 UNI 8550RolledSoft annealed18-200  100-300
1.6566UNI 7846 / EN 10084RolledSoft annealed18-32032-13040×20 –
100-600 **
1.6566UNI 7846 / EN 10084ForgedSoft annealed330-650   
1.6566UNI 7846 / EN 10084Cold drawnSoft annealed10,30-25,40   
18NiCrMo5Pb UNI 7846RolledSoft annealed22-180   
18NiCrMo5Pb UNI 7846CalledSoft annealed18-30   
18NiCrMo5Pb UNI 7846Rolled + PeeledSoft annealed20-55   
(14NiCrMo13-4 )
1.6657UNI 7846 / EN 10084RolledSoft annealed18-200   

* Blooms: finish “raw”
** Available 720×600 mm. rolled