Lead-free patenting process and equipment

A method of controlled cooling of one or multiple previously heated and substantially straight steel wire/wires to a predetermined temperature range, the previously heated and substantially straight steel wires having a diameter which is more than 3.5 mm and less than 20 mm, the method comprises the steps of:

• a) guiding the previously heated and substantially straight steel wire/wires along individual path/paths through one or multiple first coolant bath/baths, the first coolant bath/baths comprises a bath liquid, wherein the bath liquid comprises water and a stabilizing additive, wherein the bath liquid and the multiple previously heated and substantially straight steel wires create a steam film around each steel wire itself along each individual path;
• b) directing an impinging liquid immersed inside the first coolant bath/baths towards the previously heated and substantially straight steel wire/wires over a certain length L along individual path/paths, to cool down the previously heated and substantially straight steel wire/wires, wherein the impinging liquid decreases the thickness of the steam film or destabilizes the steam film, thereby increasing the speed of cooling over the length L along individual path/paths,
• c) guiding the previously heated and substantially straight steel wire/wires along individual path/paths out of the first coolant bath/baths to be further cooled down in air,
• d) after the further cooling in air, guiding the previously heated, substantially straight steel wire/wires along individual path/paths through one or multiple second coolant bath/baths,
• wherein the substantially straight steel wire/wires are subjected to a cooling transformation from austenite to pearlite.