An experimental investigation with 4 kW diodes laser system was carried out to study the effects of laser
hardening process parameters on properties of P/M steels, based on prealloyed, admixed or diffusion-bonded
powders. The surface temperature of treated zone has been measured by pyrometer (to avoid local melting or
surface damaging) and the travel speed on scanning the surface of test samples has been an investigated variable.
A special attention has been given to specimen clamping, to avoid any misalignment with the beam
movement. The independent variables investigated have been: surface temperature, T, travel speed
(mm/min). The microstructural features of the laser hardened P/M steels were analyzed using LOM and the
surface morphology has been characterized by SEM. Hardened depth (HD), hardened width (HW) and overall
cross-sectional hardened area (HA) were measured as well and used as responses for the ANOVA of the
experimental data gathered. The microhardness profiles present a sharp drop at low distance from the hardened
surface. The typical splitting between hardened zone and heat-affected zone (HAZ), well known from
laser hardened fully dense steels, holds also for P/M (porous) steels. The research showed that Laser Transformation
Hardening (LTH) is a suitable process for producing hard, wear resistant surface, on defined spots
of P/M components, through the action of a scanning laser beam.
The short heating time enables to decrease part distortion and surface oxidation, in comparison with induction
hardening. The possibility of very selective and precise hardening treatment seems to open new possibilities
to widen the use of high-property P/M parts, based on advanced design, for demanding applications
