What Does Laser Hardening Mean?
Laser hardening is a heat treatment process or surface hardening process in which a laser beam is used to heat the surface of a metal part and then let it quickly cool down in surrounding air. This process is used exclusively on ferrous materials suitable for hardening, including steels and cast iron with a carbon content of more than 0.2 percent.
Laser hardening requires less refinishing work and has the ability to process irregular, three-dimensional workpieces. Laser hardening increases hardness and wear resistance, which leads to reduction of abrasive wear.
Corrosionpedia Explains Laser Hardening
Laser hardening is a surface-hardening process commonly used for complicated shapes or large objects because it allows for absolute control on the surface hardness and texture. Laser hardening consists of the rapid heating of a material’s surface by laser beam, a short hold at the target temperature, and intensive cooling due to the high thermal conductivity of the material. During the cool-down period a process called "self-quenching" takes place, where a fine-grained structure is formed in the thin layer on the surface of the part. This process causes mechanical properties of the surface to differ from the mechanical properties of the rest of the material.
Laser hardening can be used to locally improve the wear resistance and service life of parts for a wide variety of applications, from press-forming tools to oil-drilling equipment. The technology is especially suitable for applications where minimal heat input into the surrounding material is critical. Laser hardening is typically applied for transformation hardening of ferrous materials such as hardenable steels and cast irons.
It offers many advantages over conventional heat treatment processes, including a high throughput, reproducibility and product quality. In many applications, localized treatment and minimal heat input results in reduced distortion and the rapid quench rates produce a fine microstructure.
Laser surface treatments can be divided into processes involving:
- Solid-state transformations, including:
- Martensitic hardening
- Shock hardening
- Melting processes, including:
- Dispersion hardening