Wear resistance can be improved locally by laser surface hardening. This process can be done last working phase because laser don’t cause any deformations. Apart from many other laser processes this process don’t use focused laser beam. The beam is spreaded to larger area. This is done by example using integrated mirror or scanner.
The aim of laser surface hardening is to make material properties better. It’s possible to produce hard surface and still maintain the toughness of base material.
Below are listed material properties which becomes better when using laser surface hardening
• Wear reduction
• Strenght increase
• Hardness increase
• Reduced friction
• Increase in fatique life
Laser surface hardening is used with steels with proper amount of carbon. Carbon is needed for deforming hard carbides. Another used material for laser surface hardening is cast iron steel with perlite structure.
Laser surface hardening is done by rising the surface temperature temporally over the critical transformation temperature with laser beam. Because laser beam is moved very fast over the work piece, the work piece cools very rapidly. This is because the heat input is very small. All the energy conducts to base material or to the air. Achieved surface hardness depends on the amount of carbon of base material and also cooling speed.
Laser Surface Hardening
Microstructure of hardened steel