Materials, Heat treatment, Chemical Compositions

Screws property class 4.6 to 12.9/12.9

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.

Set Screws Hardness class 14 H to 45 H

Hardness class	Material	Heat treatmenta)	Chemical composition limits (cast analysis, %) b)
			C min.	C max.	P max.	S max.
14 H	Carbon Steelc)	–	–	0.50	0.11	0.15
22 H	Carbon Steelc)	quenched and tempered	0.19	0.50	0.05	0.05
33 H	Carbon Steelc)	quenched and tempered	0.19	0.50	0.05	0.05
45 H	Carbon Steeld)e)	quenched and tempered	0.45	0.50	0.05	0.05
	Carbon steel with additivesd)	quenched and tempered	0.28	0.50	0.05	0.05
	Alloy Steeld)f)	quenched and tempered	0.30	0.50	0.05	0.05

a) Case hardening is not allowed.
b) In Case of dispute, the product analysis applies.
c) Free-cutting steel allowed with maximum lead 0.35%, maximum phosphorus 0.11% and maximum sulfur 0.34%.
d) Steel with a maximum lead content of 0.35% may be used.
e) For d maximum M16 only.
f) Alloy steel must include listed elements; combos allowed if totaling 70% of required amounts.