laser transformation hardening a material can
be case hardened with negligible distortion.
A comparison with flame and induction surface
transformation hardening techniques clearly
show that laser surface hardening is the most
advantageous process. Flame hardening has poor
reproducibility, poor quench and environmental
issues. In induction hardening a quench is required,
distortion of the part occurs and there is large
thermal penetration. With laser beam hardening
the applied light radiation instantaneously
heats the surface, there is no radiation spillage
outside the optically defined area. The bulk
of the material acts as a heat sink for the
extraction of heat from the surface. The major
advantage of laser surface treatment is high
processing speeds with precise case depths.
Laser surface transformation hardening not only
increases the wear resistance, but also under
certain conditions the fatigue strength is also
increased due to the compressive stresses induced
on the surface of the component5.
HPDDL is an ideal source for laser transformation
hardening. The line of light, when moved across
the work piece along the short axis [Figure
1] has high edge definition without the need
for special cylindrical lenses [Nd:YAG] or water
cooled integrators [CO2]. The wavelength is
800nm, which is highly absorptive, requires
no pre-coating of the work piece to get absorption.
The ISL-4000L has a modulation bandwidth of
20KHz, making ideal for in-situ temperature