Aplikovatelnost koncepce „master“ křivky pro hodnocení lomové houževnatosti C-Mn oceli na odlitky

of C-Mn cast steel has been examined in
the temperature range −140 °C to −40 °C.
The master curve concept has been applied
to evaluate the temperature dependence of
median curve KJc(med) and the upper and lower
tolerance bound, respectively. The reference
temperature T0 has been estimated as −88 °C
using six 1T SENB specimens. It is demonstrated
that all the cleavage initiated fracture toughness
results meeting the validity condition lay inside
the scatter band given by 5% and 95%
tolerance bounds. As no fracture toughness
data fall below the 5% tolerance bound,
this curve can be taken as that one determining
the lower fracture toughness values of the cast
steel examined. The temperature dependence
of the fracture toughness has been also
evaluated using exponential fit. The resulting
fracture toughness curve was almost similar
to the curves obtained by using master curve
concept.