Volume 8, Issue 2 (February 2011)
Surface Hardening of an AISI D6 Cold Work Steel Using a Fiber Laser
Laser surface treatments represent some of the most advanced and versatile processes for enhanced materials applications. Laser hardening is a technique to generate a hard wear-resistant surface microstructure in metals due to the rapid heating and cooling cycles imposed by a laser beam. This work intends to understand the influence of the laser variables on hardness after laser hardening of an AISI D6 steel. A fiber laser, which is a new source available for industrial applications, has been used. The overall absorptivity measured was ∼37 % and the laser treatment produced two different zones: Remelted and heat-affected. The surface layer was remelted and composed of martensite and retained austenite. The region next to the free surface is composed of primary austenite dendrites with martensite plates with hardness between 400 and 500 HV. The region called the heat-affect zone is composed of martensite, retained austenite, and carbides and has a hardness up to 800 HV. The case depth in laser treated samples was between 1 and 2 mm.