Localized laser hardening

Each year several billion dollars have been spent in aerospace, automotive, defence, nuclear, and energy industries for replacing functionally high-value parts due to loss of its functional properties. In this, localized laser hardening (LLH) is a promising technique to enhance the site-specific functional properties such as superior resistance to heat, wear, corrosion, fatigue, erosion, etc. Thus, part’s service life is extended. In LLH, both rapid heating by a concentrated laser beam heat source and self-quenching by bulk mass material are effectively used to obtain localized hardening. CO2 and Nd:YAG laser-based LLH are well-established, but, recently, direct diode laser-based LLH is attracting more industries owing its higher wall-plug efficiency, better absorption by metals, larger focal beam spot with more uniform power density, and lower investment and operating costs. Traditionally, LLH is confined for hardening of Steels, nowadays; it is extended to enhance the structural and functional properties of non-ferrous alloys (Al, Mg, Ti). DLLH is more energy efficient (refer below fig) where the energy is used effectively to obtain more uniform enhanced case hardness which is difficult by conventional means (arc, flame, induction). Coupled thermo-kinetic model and integrated temperature measurement system (Pyrometer, Infrared camera) have drastically reduced the materials usage, overhead cost, and time in addition to predict the in-process temperature history and case hardness. This technology is rapidly extending its commercial applications.