Suspension spring wires are oil tempered or induction hardened chromium-silicon steel wires with a diameter ranging from 8 to 15.5mm. An oil tempered wire acquires its mechanical properties by heat treatment after it has been drawn to its final size. Tempering and annealing guarantees more uniform mechanical properties than simple cold drawing. Our trade mark is Becrosi 37® and Becrosi 37 H® for higher tensile strength, according to EN10270-2 norm.