Flame hardening is a technique used to harden (or soften) certain areas of a steel part, creating a difference in hardness between these areas. The advantage of local heating of parts is less distortion and for some steel types a higher hardness.Flame hardening is most related to Induction hardening but others than Induction hardening, Flame hardening is almost unlimited is size or shape of the part so no need to build a special inductor for complex geometries. In general you can say that Flame hardening starts there where induction hardening stops. However, from a hardening profile point of view there is a significant difference between these technologies. The heating time. Whereas Induction heating time is normally very short, the Flame hardening takes a longer heating time. This has its influence on the hardening profile. The Induction hardened profile show a very abrupt hardness decrease whereas Flame hardened profile show a smoother decrease of hardness. A smoother decrease of hardness can be very helpful for heavy loaded applications.
Rotation flame hardening: Circulation hardening:
Diameter up to 1500 mm Diameter up to: 4.000 mm
Weight up to: 1200 kg Weight up to: 15.000 kg
Progressive flame hardening:
Length up to:7.500 mm
Weight up to: 20.000 kg