Prakt. Met. Sonderband 38 (2006) 291 
al surface 2. INVESTIGATION METHODOLOGY 
temporary 
N, making The materials under investigation were spicemens from the 32CrMoV12-28 and 
ace layer. X40CrMoV5-1 hot work tool steels, obtained from the vacuum cast, delivered in the form of 
nising and bars with 0.d. 75 (32CrMoV12-28) and 76 (X40CrMoV5-1) mm and in the length of 3 m. 
especially Samples of those materials were of the plate form, of the rectangular shape, with 
he global dimensions 70x25x5 mm. The chemical composition of the investigated steels is 
be Mest presented in Table 1. 
conomies Table 1 
ised SI Chemical composition of 32CrMoV/12-28 and X40CrMoV5-1 steels 
with high Mass concentration of the elements, % 
ion of the 
Agen Steeltype CC | Si Mn Ss Cc Mol vw 
este 32CrMoV12-28 0.308 | 0.25 0.37 , 020 | 0.002 . 2.95 | 2.70 | 5.35 
the liquid. 0 
ure value X40CrMoV5-1 | 0.41 | 1.09 | 0.44 10.015 | 0.010 | 5.40 | 1.41 | 0.95 0 
vices and . a an 
for the The samples were heat treated according to the steps for those steels type. Austenisation 
power up of the 32CrMoV12-28 was performed in a vacuum furnace at a temperature of 1040 °C, 
“type are the heating time 0.5h. During the heating to the austenitic temperature two isothermal 
le energy holds were applied. The first one at the temperature of 585 °C, the second at 850 °C. After 
yer. It is tempering two annealing operations were performed for the time of 2h, the first at 550 °C 
els, high and the second at 510 °C. Specimens from X40CrMoV5-1 tool steel were twice subjected 
ered io a to heat treatment consisting in quenching and tempering; austenizing was carried out in the 
terial and vacuum furnace in 1020 °C with the soaking time 0,5h. Two isothermal holds were used 
rs in the during heating up to the austenizing temperature, the first at the temperature of 640 °C and 
je lasers the second at 840 °C. The specimens were tempered twice after quenching, each time for 2 
materials hours at the temperature 560 °C and next at 510 °C. After heat treatment the surface of 
he focus specimens were grounded on magnetic grinder. Special care was set to avoid micro cracks, 
radiation which can disqualify samples in future investigations. Next, the paste of WC carbide powder 
systems was put down onto the degreased specimens. The powder was initially mixed before with 
sfficiency the inorganic sodium glass in proportion 30 % glass and 70 % powder. A paste layer of 0.05 
> reliable mm in thickness was put on. The properties of tungsten carbide powder are presented in 
g [7,8]. Table 2. The samples of the 32CrMoV12-28 and X40CrMoV5-1 steels were mounted in the 
lloy steel laser holder and next were remelted with the Rofin DL 020 high power laser beam (HPDL) 
uses the with parameters specified in Table 3. It was found in the preliminary investigations that the 
onnected maximum feed rate at which the process is stable is 0.5 m/min. Further experiments were 
nological carried out at the constant remelting rate, changing the laser beam power in the 1.2 — 2.3 
of tools. kW range during remelting the surface layer of the test pieces. 
process, 
ents and Table 2 
ol steels, Properties of the WC powder 
abrasion 
| agents Powder Grain size, ym Melting temp. °C Density, glcm® Hardness, HV3, 
igh heat 
Ws QZ2u- aJ 2730-2870 , 
pars nar HR 155