Hot Ductility of 70/30 Copper-Nickel alloys

Ductility dip cracking (DDC) is a detrimental solid-state cracking phenomenon that can occur during
welding of copper-nickel (Cu-Ni) alloys used in naval vessels. The presence of these cracks has several
deleterious effects, including reduced fatigue life and increased susceptibility to corrosion. The
mechanism of DDC remains highly debated and understudied, especially in material systems outside of
Ni-Cr-Fe alloys. The predominant mechanisms that have been proposed include: 1. Grain boundary
sliding, 2. Precipitate-induced strain, and 3. Impurity element segregation. In the present body of research,
thermal-mechanical testing over a wide range of strain rates and temperatures were performed using a
Gleeble 3500. Both flow-stress and fracture mechanism of wrought 70/30 Cu-Ni are considered.
Following fracture, extensive microscopic analyses using both scanning electron microscopy and optical
microscopy were conducted to observe and quantify intergranular cracking and fracture surface
morphology. Results show a strong correlation among fracture morphology, ductility, and temperature.