  The analysis and understanding of creep damage of Grade 91 steel welded
joints is an important topic in the energy industry. Creep tests on welded
joints were carried out at 600$^{\circ}$C, 100MPa and then interrupted at 0%,
10%, 30%, 50%, 80% of the expected life and after failure. Creep damage is
characterised by cavity bands located exclusively in the core of the sample in
the InterCritical Heat Affected Zone (ICHAZ). These samples were tested using
\textit{in situ} synchrotron XRD along the welded joint under creep conditions
for the different creep life time. The experimental results show a significant
strain evolution and creep damage characteristic on the welded joint, with a
local maximum at the Heat Affected Zone (HAZ). Following this, a finite element
creep strain analysis was performed for comparison with the experimental
results.
