UNI ISO 898-1:2009
STEELS
Property class	Material and heat treatment				Chemical composition limits (cast analysis %)					Tempering temperature
					C		P	S	B
					min	max	max	max	max	°C min
4.6	Carbon steel or carbon steel with additives				-	0.55	0.050	0.060	Not Specified	-
4.8					-	0.55	0.050	0.060
5.6					0.13	0.55	0.050	0.060
5.8					-	0.55	0.050	0.060
6.8					0.15	0.55	0.050	0.060
8.8	Carbon steel with additives (e.g. Boron or Mn or Cr) quenched and tempered				0.15	0.40	0.025	0.025	0.003	425
	Or
	Carbon steel quenched and tempered				0.25	0.55	0.025	0.025
	Or
	Alloy steel quenched and tempered				0.20	0.55	0.025	0.025
9.8	Carbon steel with additives (e.g. Boron or Mn or Cr) quenched and tempered				0.15	0.40	0.025	0.025	0.003	425
	Or
	Carbon steel quenched and tempered				0.25	0.55	0.025	0025
	Or
	Alloy steel quenched and tempered				0.20	0.55	0.025	0.025
10.9	Carbon steel with additives (e.g. Boron or Mn or Cr) quenched and tempered				0.20	0.55	0.025	0.025	0.003	425
	Or
	Carbon steel quenched and tempered				0.25	0.55	0.025	0.025
	Or
	Alloy steel quenched and tempered				0.20	0.55	0.025	0.025
12.9	Alloy steel quenched and tempered				0.30	0.50	0.025	0.25	0.003	425
12.9	Carbon steel with additives (e.g. Boron or Mn or Cr) quenched and tempered				0.28	0.50	0.025	0.025	0.003	380