Abstract :
The most commonly used test standards
for performing Charpy impact tests (ISO 148 and
ASTM E 23) envisage the use of strikers having different
radii of the striking edge, i.e. 2mm (ISO) and 8mm
(ASTM). The effect of striker geometry on Charpy
results was extensively studied in the past in terms of
absorbed energy measured by the machine encoder,
but few investigations are available on the influence
of striker configuration on the results of instrumented
Charpy tests (characteristic forces, displacements and
integrated energy). In this paper, these effects are investigated
based on the analysis of published results from
three interlaboratory studies and some unpublished
Charpy data obtained at SCK·CEN. The t-test was used
for establishing the statistical significance of the
observed effects. The instrumented variables which are
the most sensitive to the radius of the striking edge
are the maximum force and its corresponding displacement,
with 8 mm-strikers providing systematically
higher values. The effect on general yield forces, on
the other hand, is less consistent and more difficult to
rationalize, although 2 mm-strikers generally tend to
deliver higher values. Absorbed energies, obtained both
from the instrumented trace and from the pendulum
encoder, are almost insensitive to the type of striker up
to 200 J. For higher energy levels, the values obtainedfrom 8 mm-strikers become progressively larger. Data
scatter is generally higher for 2 mm-strikers
