Prakt. Met. Sonderband 38 (2006) 293 
remelting trays (Figs. 2 and 3). Metallographic investigations were performed also using the 
scanning electron microscope DSM 940 supplied by OPTON. 
a, 
Fig. 2 Shape and thickness of cross section of the laser remelted samples from the 
32CrMoV12-28 steel, a) WC laser by power 1.2 kW, b) WC 2.3 kW, magnification 50x 
m. It was 
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ting and 
aj 
Fig. 3 Shape and thickness of cross section of the laser remelted samples, X40CrMoV5-1 
steel, a) WC laser by power 1.2 kW, b) WC 2.3 kW, magnification 50x 
Phase composition and crystallographic structure were determined by the X-Ray diffraction 
method using the DRON 2.0 device with a cobalt lamp, with 40 kV voltage. The 
measurements were made in the angle range 26: 30°+105°. 
3. INVESTIGATION RESULTS 
Metallographic examinations carried out on the light microscope confirm that the 
microstructure of the material solidifying after laser remelting is diversified and is dependant 
on the solidification rate of investigated steels. Occurrence of microstructure with big 
dendrites was revealed in areas at the interface the solid and liquid phases. Microstructure 
presented on figures 4 and 5 show a dendritic structure in remelted area. There is clean 
relationship between the employed laser power and the dendrite size, namely with 
increasing laser power the dendrites are larger. It was found out, that the structure of the 
material solidifying after laser melting is characterized by the occurrence of areas with 
diversified morphology connected with the crystallization of the steels. In case of alloying 
with the tungsten carbide powder, which melting point is much higher than the melting point 
ar to the of steel, with the initially specified laser power, inundation occurs of the un-molten WC 
ure was powder grains into the molten steels substrate. The hot work tool steel has a ferritic 
im Al203 microstructure with homogeneously distributed carbides in the metal matrix in the annealed 
ed resin state. After tempering martensitic microstructure is achieved, in the martensite are dissolved 
> for the the alloyed additives, which was confirmed by the chemical EDX analysis. 
ace layer 
0+500x. 
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