Alloy steels for carburizing are a group of steels containing up to 0.25% of carbon and are destined for surface hardening with 
carburizing method, or cyanidizing (at the same time nitriding and carburizing). After carburizing hard surface is obtained
maintaining the ductility of the core in a hardened condition and tempered low 150-180 ° C. Steels for carburizing are used in
order to get a high surface resistance to abrasion and when it is necessary to obtain a high hardness. The greatest hardness after
carburizing get the steels containing chromium and molybdenum. Parts of the small cross-sections are made of steel containing
chromium and manganese, large items are made of steel containing chromium and nickel or chromium + nickel + molybdenum.
In the grade marking number at the beginning means the average content of carbon in hundredths of %, next the letters denoting
H - Chrome
G - Manganese
N - Nickel
M - Molybdenum
W - Tungsten
T - Titanium
if there are numbers after the letters they refer to the average content of a certain component in %.
If there the letter A appears at the end of the marking of the steel it means less the content of sulfur i phoshphorus.
For example, 18H2N2 steel marking indicates that the average carbon content is 0.18%, steel contains about 2% of chromium and
2% of nickel.

Huta Piłsudski 1935-1939
15HN - chrome-nickel steel
17HNM - stainless chromium-nickel-molybdenum
18HGT - chrome-manganese-titanium
18H2N2 - chrome-nickel steel
18H2N4WA,(18H2N4MA) - chrome-nickiel-tungsten
20H2N4A - chrome-nickel steel
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