Product Specification

BS EN 10270-2 Oil hardened and tempered spring steel wire for mechanical springs

oil hardened and tempered spring steel wire that is heat treated in line in the following way: it is first transformed into austenite, quenched in oil or similar quenching medium, followed immediately by tempering by heating to the appropriate temperature.

oil hardened and tempered spring steel wire made from unalloyed or alloyed steels. They are primarily subject to torsional stresses such as in compression and extension springs and in special cases also for applications where the spring wire is subject to bending stresses such as lever springs. As a rule unalloyed steels are used for applications at room temperature whereas alloyed steels are generally used at a temperature above room temperature. Alloyed steels may also be chosen for above average tensile strengths.

Oil hardened spring steel wire Chemical composition

Oil hardened and tempered spring steel wire Classification

The grade for normal applications made from unalloyed or alloyed steel has the abbreviation FD and is intended for static applications.

Spring steel wire for medium fatigue levels, such as required for some clutch springs from unailoyed or alloyed steel, has the abbreviation TD.

Spring steel wire from unalloyed steel or alloyed steel intended for use under severe dynamic duty such as for valve springs or other springs with similar requirements has the abbreviation VD.

Medium and high fatigue grades TD and VD are characterized by high steel cleanliness, specific chemical, mechanical and technological parameters and a well defined surface condition in relation to the allowable depth of surface defects and decarburization.

The static grade FD is characterized by its chemical, mechanical and technological characteristics as well as by a specified surface condition concerning surface defects and decarburization.

Oil hardened spring steel wire Dimensional tolerances

Wire in coils

The tolerances level for the wire diameter is based on EN 10218-2:1996 level:

-T5 for wire diameter up to and including 0,80 mm;

-T4 for 0,80 mm up to 10,00 mm;

-T3 above 10,00 mm.

Wire in cut lengths

The requirements for length tolerances and straightness are as in EN 10218-2:1996. The tolerance on the nominal length shall only be in plus keeping the same tolerance range

Non metallic inclusions

The VD grades shall be checked for maximum size of inclusion according to ENV 10247. The allowable level of inclusions shall be agreed between the parties at the enquiry and order.

Form of delivery

Oil hardened and tempered wire shall be supplied in coils, on spools or in cut lengths. The wire in coils or on spools shall form one continuous length. Wire in coil may also be supplied on carriers containing one or more coils.

For VD and TD grades no welds are permitted after the heat treatments preceding the final drawing operation; for 'FD' grades no welds shall be made at finished size unless agreed otherwise between the parties.

The supplied wire units shall be tightly bound to ensure that wire spiral waps do not spring out unforeseen. The starting end shall be marked and at the coil ends the wire shall be covered with a protective cap.

Oil hardened spring steel wire Surface finish

The wire shall be protected against corrosion and mechanical damage. Unless otherwise specified the wire shall be delivered in slightly oiled condition.

Oil hardened spring steel wire Surface quality

The surface of the wire shall be smooth and permissible depth of surface defects at the coil ends shall be in accordance with Table.

By in-line control of surface defects the areas of the coil with defects above the level of Table 7 shall be marked. In-line testing is not performed for FD-grades.

The number of defective parts that can be tolerated may be agreed between the parties.

Surface decarburization

The wire grades according to this standard shall be free from total decarburization. The maximum depths of the partially decarburized zone shall be checked at the end of the coils.

Testing and inspection

Coiling test

Torsion test

heat analysis;

result of the tensile test

result of the torsion test

actual wire diameter

Tensile test

Information to be supplied by the purchaser

The purchaser shall clearly state in his enquiry or order the product and following information :

a)the desired quantity;

b)the number of this European Standard: EN 10270-2;

c)wire grade

d)the nominal wire diameter;

e)the form of delivery and unit mass;

f)the type of inspection document;

g)any particular agreement made.