Otelul este un aliaj ce contine ca elemente principale fierul si carbonul, avand un continut de carbon sub 2,11 %. Aliajele fier-carbon cu mai mult de 2,11% carbon se numesc fonte.

Otelurile sunt materialele cu cea mai larga utilizare in industrie. Proprietatile lor pot sa varieze in limite foarte largi in functie de continutul de carbon si de alte elemente de aliere.

Marci echivalente:

EN 10083/1 EN 10083/2	Werkstoff No.	DIN 17200 1652	STAS 880	AFNOR NFA33101; 35551;	B.S. 970 1449	UNI 7845 8373	JIS G4051	GOST 1050	AISI/SAE ASTM
1C22	1.0402	C 22	OLC 20	AF 42 XC18	055M15 070M20 22HS, CS	C20 C21 C25	S20C S22C	20	(M)1020 M1023
2C22	1.1151	Ck 22	OLC 20X	XC18	055M15	C20 C25	S20C S22CK S22C	20	1020 1023
3C22	1.1149	Cm 22	OLC 20XS	XC18 u	-	-	-	-	M1023
1C25	1.0406	C 25	OLC 25	XC25	070M26	C25 1C25	-	-	(M)1025
2C25	1.1158	Ck 25	OLC 25X	XC25	070M26	C25	S25C S28C	25	1025
3C25	1.1163	Cm 25	OLC 25XS	XC25u	-	-	-	-	1025
1C30	1.0528	C 30	OLC 30	AF50 XC32	080M30	C30, 1C30	-	-	1030
2C30	1.1178	Ck 30	OLC 30X	AF50,XC32	080M30	-	530C	30	1030
3C30	1.1179	Cm 30	1.1179	XC32 u	-	-	-	-	1030
1C35	1.0501	C 35	OLC 35	AF55 XC38 XC32	080A32 080A35 080M36 40CS	C35 1C35	S35C	35	1035
2C35	1.1181	Ck 35	OLC 35X	XC32 XC38H1	080A35	C35	S35C	35	1035 1038
3C35	1.1180	Cm 35	OLC 35XS	XC38H1u	-	-	-	-	1035
1C40	1.0511	C 40	OLC 40	XC42H1 AF60	080M40	C40 1C40	-	-	1040
2C40	1.1186	Ck 40	OLC 40X	AF60 XC42H1	060A40 080A40 080M40	C40	S40C	40	1040
3C40	1.1189	Cm 40	OLC 40XS	XC42H1u	-	-	-	-	1040
1C45	1.0503	C 45	OLC 45	AF65 XC45	060A47 080M46 50HS,CS	C45 1C45	S45C	45	1045
2C45	1.1191	Ck 45	OLC 45X	XC45H1u	080M46 060A47	C45 C46	S45C S48C	45	1045
3C45	1.1201	Cm 45	OLC 45XS	XC42H1u XC48H1u	-	-	-	-	1049
1C50	1.0540	C 50	OLC 50	-	080M50	1C50	S50C	50	1049 1050
2C50	1.1206	Ck 50	OLC 50X	-	080M50	-	S50C	50	1049 1050
3C50	1.1241	Cm 50	OLC 50XS	-	-	-	-	-	1050
1C55	1.0535	C 55	OLC 55	AF70,C55	070M55	C55 1C55	S55C	55	1055
2C55	1.1203	Ck 55	OLC 55X	XC55H1	060A57 070M55	C55	S55C	55	1055
3C55	1.1209	Cm 55	OLC 55XS	XC55H1u	-	-	-	-	1055
1C60	1.0601	C 60	OLC 60	-	060A62 HS, CS	C60 1C60	S58C	60	1060
2C60	1.1221	Ck 60	OLC 60X	-	060A62	C60	S58C	60 60G 60GA	1060 1064
3C60	1.1223	Cm 60	OLC 60XS	-	-	-	-	-	1064

Compozitie chimica

STEEL	CHEMICAL COMPOSITION, % BY WEIGHT
GRADE	C	Si max	Mn	P max	S max
1C 22 2C 22 3C 22	0.17-0.24	0.40	0.40-0.60	0.045 0.035 0.035	0.045 0.035 0.020-0.040
1C 25 2C 25 3C 25	0.22-0.29	0.40	0.40-0.70	0.045 0.035 0.035	0.045 0.035 0.020-0.040
1C 30 2C 30 3C 30	0.27-0.34	0.40	0.50-0.80	0.045 0.035 0.035	0.045 0.035 0.020-0.040
1C 35 2C 35 3C 35	0.32-0.39	0.40	0.50-0.80	0.045 0.035 0.035	0.045 0.035 0.020-0.040
1C 40 2C 40 3C 40	0.37-0.44	0.40	0.50-0.80	0.045 0.035 0.035	0.045 0.035 0.020-0.040
1C 45 2C 45 3C 45	0.42-0.50	0.40	0.50-0.80	0.045 0.035 0.035	0.045 0.035 0.020-0.040
1C 50 2C 50 3C 50	0.47-0.55	0.40	0.60-0.90	0.045 0.035 0.035	0.045 0.035 0.020-0.040
1C 55 2C 55 3C 55	0.52-0.60	0.40	0.60-0.90	0.045 0.035 0.035	0.045 0.035 0.020-0.040
1C 60 2C 60 3C 60	0.57-0.65	0.40	0.60-0.90	0.045 0.035 0.035	0.045 0.035 0.020-0.040