- During batch annealing, the wire is heated for several hours at temperatures as high as 700°C, under a protective atmosphere like nitrogen or hydrogen to avoid oxidation or decarburization. This recrystallisation treatment renders the wire homogeneously softer. Hydrogen Annealing is used in-process, to soften the metal for additional cold working, or at finish, for maximum formability. We provide a decarb-free product. The hydrogen-reducing atmosphere contains no oxygen and stainless-clad annealing chamber prevents moisture penetration. It finds its way into the smallest crevices of the material to burn off all surface contaminants. This atmosphere provides the best heat distribution and uniform temperature control to result in a bright surface finish.
- During patenting the wire is continuously heated to about 1000°C, rapidly quenched and held for some seconds at about 550°C to allow for a full isothermal transformation into sorbite.
Patenting transforms the steel structure into a homogenous fine perlitic structure, known as sorbite. This is the optimal structure to create the highest mechanical properties for further cold deformation.
- During hardening and tempering, the wire is continuously heated to about 950°C, then quenched to room temperature to create a martensitic structure, and subsequently re-heated to about 450°C to add ductility. Hardening and tempering create high mechanical properties and superior fatigue behavior in highly dynamic applications.
These three treatments are used to create specific characteristics for specific applications.