Subsea power cable sheathing: an investigation of lead fatigue performance

The protection of subsea power cables against electrical failure is achieved by the use of a watertight layer. Due to its properties
of chemical stability and ductility, lead has been the material of choice for this purpose for several decades. Due to the low
melting temperatures of lead alloys, their behaviour is strongly influenced by time-dependent phenomena, such as creep and
recrystallization, which become more prominent for lower strain rate deformations. In order to understand the performance of the
alloys of interest under cyclic loading experienced during and after installation in combination with the different variables
influencing its behaviour, extensive testing is necessary. This manuscript presents the results of fatigue tests at two different
strain rates for an alloy of industrial interest. The tests are monitored with the aid of digital image correlation, which greatly
reduces the uncertainty on the quantification of the real strain field. The post-mortem fracture surfaces are investigated through
scanning electron microscopy and metallurgical characterization to help understanding the differences in the failure modes active
in the different stress/strain regimes.