Materials, Heat treatment, Chemical Compositions

Property class	Material and heat treatment	Chemical composition limits (cast analysis, %) 1)				B 2) max.	Tempering temperature °C min.
		C min.	C max.	P max.	S max.
4.6 3),4)	Carbon steel or carbon steel with additives	–	0.55	0.05	0.06	not specified	–
4.8 4)		–	–	–	–
5.6 3)		0.13	0.55	0.05	0.06
5.8 4)		–	0.55	0.05	0.06
6.8 4)		0.15	0.55	0.05	0.06
8.86)	Carbon steel with additives (e.g. Boron or Mn or Cr), quenched and tempered	0.155)	0.40	0.025	0.025	0.003	425
	or Carbon steel, quenched and tempered	0.25	0.55	0.025	0.025
	or Alloyed steel, quenched and tempered 7)	0.20	0.55	0.025	0.025
9.86)	Carbon steel with additives (e.g. Boron or Mn or Cr), quenched and tempered	0.155)	0.40	0.025	0.025	0.003	425
	or Carbon steel, quenched and tempered	0.25	0.55	0.025	0.025
	or Alloyed steel, quenched and tempered 7)	0.20	0.55	0.025	0.025
10.96)	Carbon steel with additives (e.g. Boron or Mn or Cr), quenched and tempered	0.205)	0.55	0.025	0.025	0.003	425
	or Carbon steel, quenched and tempered	0.25	0.55	0.025	0.025
	or Alloyed steel, quenched and tempered 7)	0.20	0.55	0.025	0.025
12.9 6),8),9)	Alloyed Steel, quenched and tempered 7)	0.30	0.50	0.025	0.025	0.003	425
12.9 6),8),9)	Carbon steel with additives (e.g. Boron, Mn or Cr or Molybdenum), quenched and tempered	0.28	0.50	0.025	0.025	0.003	380

1 In case of dispute, product analysis applies.
2 Boron up to 0.005% allowed if controlled with Ti/Al.
3 For classes 4.6 & 5.6, heat treatment may be needed for ductility.
4 Free cutting steel max: S 0.34%, P 0.11%, Pb 0.35%.
5 Plain carbon boron (<0.25%C): Mn =0.6% (8.8), =0.7% (9.8/10.9).
6 Material must harden to ~90% martensite before tempering.
7 Alloy steel must contain: Cr 0.3%, Ni 0.3%, Mo 0.2%, V 0.1% (70% sum if combined).
8 White phosphorus layer not permitted for class 12.9/12.9.
9 For class 12.9/12.9, check manufacturer capability & avoid stress corrosion cracking.