Patenting

Patenting is usually done on the wire material after descaling or scale drawing to remove any martensite formed during scaling or after the wire has been deformation hardened during drawing. The process involves increasing the temperature of the wire in the austenite range – about 900 °C – and then lower the temperature in a lead bath, salt bath or fluidised bed at a temperature of 500 to 690 ºC depending on the alloy. The wire will then have a fine lamellar structure of pearlite/ferrite which then allows further drawings.

The speed steel material may need three to five processes to give the wire softer properties for further drawing.