Prakt. Met. Sonderband 46 (2014) 311 
Jane 20 5 
1050 °C 180 © 
+ 1020 °C 1 
- 120 
100 
LOB 
“oto 1020 1030 1040 1050 1060 1070 
Austenitization Temperature {°C} 
retained Figure 3: Results from the impact toughness together with austenite grain size (left). 
Micrograph (SEM), a ductile fibrous kind of fracture with some voids (right). The 
direction of growth of crack is from left to right. Specimen austenitized at 1020°C and 
tempered at 200°C 
on at a lower 
The fracture 
s and dimple 
erature loses 
4 shows the 
. It is evident 
ce to plastic 
contribute to 
w tempering Figure 4: Light optical micrograph showing the coarsening of the prior austenite grain, 
this study it 1020°C (left), 1050°C (middle) and 1075°C (right). Etched with Pikral and 10% Nital 
the effect of for 3s. The micrograph is taken at magnification of 100X and the scale is 10um. 
hed retained 
recipitation at 4. CONCLUSION 
> presence of 
al less tough. The effects of austenitization temperatures and tempering treatments on microstructure 
Ss good wear and impact toughness has been studied for the cold work tool steel ’Uddeholm Caldie’ and 
vor the crack conclusions are presented below: 
° studies are 
the resulting Higher hardness, large amount of retained austenite and large prior austenite grains 
were found for higher austenitization temperatures. 
A Secondary hardening peak is found around 525°C. Impact toughness decreased 
with increasing austenitizing temperature but was highest for the low tempering 
temperatures. Secondary hardening is caused by dissolution of retained austenite 
and secondary carbide precipitates.