Influence
of Size in Miniature Specimen on Result of Small-sized Impact Test
Ken MURAMATSU
Mechanical &
Electrical Engineering Course Student, Advanced Engineering Course,
Ooka 3600, Numazu-si, Shizuoka-ken, 410-8501
Impact
Strength of industrial material is investigated by Charpy
impact test. The small-sized Charpy impact test has
been performed in our laboratory. It has effectiveness in following the situation,
reduce the examination’s cost and don’t prepare the full-sized specimen. But
the result of Charpy impact test was changed by
influence of size in specimen. So, to clarify the influence of size in
miniature specimen, In this study, influence of length
and cross-sectional area, on result of impact test was investigated. The impact
energy data was, however, not obtained enough since almost specimens were not
broken. Localized irregularity in microstructure and hardness around notch
induced by heat treatment or machining was not
observed. It was apparent that specimens were uniformly prepared and were
softer than expected. Moreover, specimen with 32mm length was not broken while
that with 8mm length was. It was considered that specimen with 8mm length was
broken by bending with hummer and holder. It was suggested that specimen size,
length and cross-sectional area, and design of testing device, clearance
between hummer and holder, have to be reexamined for the accurate small-sized
impact test.
Key Words: Material Testing, Impact Strength , Charpy,
Ductile Fracture, Bending,