Principle laser hardening
During the process of laser hardening, carbonaceous material (min. 0,2% carbon) is briefly heated by laser light. The temperature remains just below the melting point. Due to fast cooling, the metal can no longer form itself to its original condition. This results in a martensitic structure which is considerably harder then austenitic.
It’s important to prevent melting of the material during the process of hardening. Solified material structure is particularly rough and contains additional tension. In order to achieve a nice, continuous laser hardening and avoid a ‘melting pool’, extensive knowledge is required about:
- Material properties
- Temperature/heat input
- Speed and accelerations of CNC laser machine
- Master the parameter ‘movement speed’ results in a constant hardening
- Laser light & wave lengths
- Among others, the laser beam diameter + frequency determines the intensitiy of the radiated laser light. Fluctuating and inaccurate radiation of laser beams results in different hardness values.
Advantages of hardening by laser
- Hardening of difficult to reach surfaces (3D)
- Partially hardening, without risking excessive hardening
- Increase surface resistance (increase Vickers hardness values)
- Lower friction coefficient
- Efficient (minimum) heat input, less distortion