Abstract
Heat treatable 6000 series (AlMgSi) alloys
are attractive in many applications in
the building and transport sector due to
a favourable combination of good formability,
moderately high strength and
good corrosion resistance. However, unfavourable
alloying and thermomechanical
processing may cause susceptibility to
intergranular corrosion (IGC) in chloride
containing environments. IGC is mostly
observed in alloys where small amounts
of copper have been added to improve
the mechanical properties and in alloys
with a high Si/Mg ratio. The susceptibility
has been related to the segregation
of a copper-rich layer (only detectable
by high-resolution scanning transmission
electron microscopy) and cathodic
Q-phase precipitates along the grain
boundaries, causing anodic dissolution of
the adjacent solute depleted precipitate
free zone [1].
are attractive in many applications in
the building and transport sector due to
a favourable combination of good formability,
moderately high strength and
good corrosion resistance. However, unfavourable
alloying and thermomechanical
processing may cause susceptibility to
intergranular corrosion (IGC) in chloride
containing environments. IGC is mostly
observed in alloys where small amounts
of copper have been added to improve
the mechanical properties and in alloys
with a high Si/Mg ratio. The susceptibility
has been related to the segregation
of a copper-rich layer (only detectable
by high-resolution scanning transmission
electron microscopy) and cathodic
Q-phase precipitates along the grain
boundaries, causing anodic dissolution of
the adjacent solute depleted precipitate
free zone [1].