A Japanese research group reported in 2008 susceptibility
to stress corrosion cracking of oxygen free phosphorous
doped copper (CuOFP) in sulphide containing sea water at
T = 80°C and under uniaxial slow dynamical loading
conditions. More evidence for stress corrosion cracking
has not been found under multiaxial constant loading
conditions in sulphide containing groundwater at T =
25°C. Indications of possible sulphur ingress to CuOFP
grain boundaries from sulphide containing groundwater
were found, which initiated further studies on the
possibility of grain boundary embrittlement through such
ingress. Further studies were conducted in order to
clarify the effect of sulphide exposure on the mechanical
behaviour of CuOFP.
Tensile and creep tests were performed with specimens
exposed to sulphide and reference specimens. In the
studies presented in this paper only small
con-centrations or no sulphur at all was found on
fracture surfaces, in contradiction with earlier studies
with precracked compact tension (CT) specimens under
constant load. It is suggested that the high
concentrations found earlier may have been caused by the
method of opening up the fracture surfaces (i.e.
post-exposure fatigue in air) and thus be an artefact.
The tensile tests performed after the exposure to
sulphide containing ground-water indicate a degrading
influence of the exposure on mechanical properties of
CuOFP. The result is based on adequate number of
specimens and a standard test practise.
The creep tests performed within the studies presented in
this paper seem to indicate a minor degrading influence
of the exposure to sulphide containing groundwater.
However, when compared with all the publicly available
creep data on CuOFP from different heats and laboratories
the current finding is still within the scatter band.
|BALTICA IX - International Conference on Life Management and Maintenance for Power Plants
|11/06/13 → 13/06/13