292 Prakt. Met. Sonderband 38 (2006) 
Table 3 ren 
Technical data for the HPDL Rofin 020 SCH 
Parameter Value 
Wavelength of the laser radiation, nm 940+5 
Power range, W N 100+2300 
Focal length of the laser beam, mm 82/32 
Laser spot size, mm 1.8x6.8/1.8x3.8 
Power density range of the laser beam in N 
_ the focus plane, kW/cm? 0.8+36.5 
On each sample surface four laser process trays were made of a length of 25 mm. It was 
established experimentally that the argon — blow with the flow rate 20 l/min. trough the © 
12 mm circular nozzle oppositely directed in respect to the remelting direction provides full 
remelting zone protection (Fig. 1). The specimens were machined after remelting and 
alloying, to remove the non remelted layer of tungsten carbide. a, 
Rofin DL 020 Fi 
Phe 
. met 
hte me: 
Specimen 3 
Met 
mici 
on 
den 
pres 
rela 
incr 
mat 
Fig. 1 The high power diode laser dive 
with 
The remelted test pieces were cut on the Struers device in the plane perpendicular to the of s 
remelting direction. For the preparation the standard metallographic procedure was pow 
applied in form of grinding using SiC 220, 500, 800 and 1200, polishing with 1 um Al,O4 mic 
polishing paste, and drying, the samples were mounted in the thermo hardened resin stat 
supplied by Struers. Next the samples were etched in nital at room temperature for the the 
experimentally chosen time selected individually for each remelted area. 
Metallographic examinations of the material microstructures after laser alloying surface layer 
were made on Zeiss Leica MEF4A light microscope in a magnification range of 50+500x. 
The observations were performed on the cross section of the samples on each of the