Fracture mechanics properties and failure mechanisms of environmental-friendly brass alloys under impact, cyclic and monotonic loading conditions, Engineering Failure Analysis, 2018, Vol. 90, pp. 497-517
Abstract
Final heat treatment was applied for the microstructural modification and
machinability improvement of Pb-free brass alloys, namely CW510L and CW511L. In
the frame of the assessment of the structural integrity of such components in terms
of fracture toughness and damage tolerance, the crack-resistance was studied
employing fracture mechanics testing techniques, such as impact toughness (Charpy)
and Crack-Tip-Opening-Displacement (CTOD) according to ISO 148-1 and BS 7448-1
standards respectively. The heat treated CW510L at 775o
C for 60 min exhibited an
improvement of fracture toughness in terms of impact energy (from 47 J to 52 J) and
critical CTOD (from 0.32 mm to 0.50 mm), while in case of CW511L heat treatment
performed at 850o
C for 120 min caused a slight deterioration of fracture toughness
in terms of impact energy (from 104 J to 84 J) and critical CTOD (from 0.71 mm to
0.54 mm). Moreover, fractographic analysis was comprehensively performed at the
various transition fracture zones and the emergent failure mechanisms were
identified and documented for both examined brass manufacturing conditions (“as
received” and after “final heat treatment”). The compilation of fracture mechanics
properties and the acquired fractographic information have resulted evidently in the
formulation of salient interpretation and postulation of hypotheses concerning the
influence of the dominant microstructure and loading regimes on crack propagation
and the observed failure mechanisms.