ISO 683-4 Grade 35SPb20 Untreated – High‑Strength Free‑Cutting Steel for Automotive and Machinery Parts

The free-cutting steel 35SPb20, suitable for quenching and tempering, is used for bulk parts of mean strength, especially for lower requirements to ductility in transversal direction opposite to comparable C-steels (e.g. C35). Machinability enhancement is achievable by Pb-content. Application in automotive engineering, as well as in apparatus equipment and machine engineering (e.g. screws, nuts, small-size parts).

Properties

General

Property	Temperature	Value
Density	20.0 °C	7.85 g/cm³

Mechanical

Property	Temperature	Value	Comment
Elastic modulus	20.0 °C	210 GPa
	200.0 °C	193 GPa
	300.0 °C	185 GPa
	400.0 °C	175 GPa

Hardness, Brinell	20.0 °C	149 - 210 [-]
Poisson's ratio	23.0 °C	0.29 [-]	Typical for Medium Carbon Steel
Shear modulus	20.0 °C	81 GPa
Tensile strength	20.0 °C	500 - 720 MPa

Thermal

Property	Temperature	Value	Comment
Coefficient of thermal expansion	100.0 °C	1.1E-5 1/K
	200.0 °C	1.18E-5 1/K
	400.0 °C	1.32E-5 1/K

Max service temperature		500 °C	Typical for Carbon Steel
Melting point		1380 - 1514 °C	Typical for Medium Carbon Steel
Specific heat capacity	20.0 °C	420 J/(kg·K)
	100.0 °C	490 J/(kg·K)
	200.0 °C	530 J/(kg·K)
	400.0 °C	610 J/(kg·K)

Thermal conductivity	20.0 °C	49 W/(m·K)

Electrical

Property	Temperature	Value
Electrical resistivity	20.0 °C	1.2E-7 Ω·m

Chemical properties

Property	Value
Carbon	0.32 - 0.39 %
Lead	0.15 - 0.35 %
Manganese	0.7 - 1.1 %
Phosphorus	0.06 %
Silicon	0.4 %
Sulfur	0.15 - 0.25 %

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Metal