When homogeneous materials with a residue-free surface and unparalleled forming properties are required, Waelzholz’s patented high-speed hardening and tempering method is the solution of choice. The process of heating the steel strip to well over 800 °C in a few fractions of a second and cooling it just as quickly produces an extremely fine-grained and homogeneous martensite microstructure. This is how we manufacture flat wire products and profiles made of wire with above-average bending uniformity and residue-free surfaces, such as those required for a variety of applications in the automotive industry.
When manufacturing flat wire and profiles made of wire, Waelzholz implements its patented high-speed hardening and tempering process on specially developed production lines using two different methods. In both inductive and conductive hardening and tempering, current is applied to the flat rolled wire, which heats it due to a phenomenon known as resistance heating. In the inductive method, current is applied without any contact by means of a magnetic field; in the conductive method, on the other hand, the electrical charge is applied via rollers that come into contact with the surface of the material. Since the energy is applied directly to the material in both methods without any transition losses, they not only effectively and uniformly harden and temper the materials, but also do so in a particularly energy-efficient manner.
Matthias Schmitt, materials technology specialist, explains: “With the help of these special hardening and tempering methods, we are able to heat flat wire products and profiles made of wire to well over 800 °C within fractions of a second and then cool them down again in an instant. Due to these incredibly rapid temperature changes, the hardening and tempering process is already complete before larger grains can form in the microstructure. This is how we produce a uniformly fine-grained, extremely homogeneous martensite microstructure that is impossible to achieve using conventional hardening and tempering methods.”