CRACK INITIATION AND PROPAGATION
RESISTANCE OF HSLA STEEL WELDED JOINT CONSTITUENTS
M. Jovanović1, I. Čamagić1, S.A.
Sedmak2, P. Živković1, A. Sedmak3
Faculty of Technical Sciences, Kosovska Mitrovica, SERBIA
University of Belgrade, Innovation Centre of the Faculty of Mechanical
Engineering, Belgrade, SERBIA
University of Belgrade, Faculty of Mechanical. Engineering, Belgrade, SERBIA
The welded joint is heterogeneous in its microstructure, mechanical and
geometrical properties, thus the stress field is affected by different factors
as well as by residual stress. Therefore, special procedures are needed for
experimentally determining the fracture toughness in plane strain, KIc,
and the impact toughness, usually associated with difficulties in interpreting
the measured values. Notched specimens are tested by instrumented Charpy in
order to determine impact energy and crack initiation and propagation energies.
The pre-cracked specimens are tested by standard, using three-point bending
specimens, as geometrically closest to Charpy specimens. In both cases, the
notch and crack are located in all various regions of the welded joint of the
high-strength low alloyed steel NIONIKRAL-70. Analysis of the results includes
speculations on the ratio of energies for crack initiation and propagation vs.
Keywords: welded joint, fracture toughness, impact energy, crack
initiation energy, crack propagation energy