Nanostructure evolution and mechanical property changes during aging of a super duplex stainless steel at 300°C

• The nanostructure evolution and the corresponding changes in mechanical properties of a super duplex stainless steel 2507 (UNS S32750) during aging at 300. °C up to 12,000. h have been investigated. Microstructural studies using transmission electron microscopy and atom probe tomography show that subtle Cr concentration fluctuations develop during aging. The amplitude of the concentration fluctuations is proportional to the hardness of the ferrite phase, and it is also proportional to the decrease in room temperature impact toughness during aging. The fracture behaviour of the alloy changes gradually from ductile to cleavage fracture, upon aging. The cracks were found to propagate through the ferrite phase, partly along deformation twin interfaces, and delamination between the austenite and ferrite phases was observed.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Nanoteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Nano-technology (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Materialteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Metallurgi och metalliska material (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Metallurgy and Metallic Materials (hsv//eng)

Nyckelord

Atom probe tomography (APT)

Duplex stainless steel

Mechanical properties

Phase separation

Spinodal decomposition

Transmission electron microscopy (TEM)

Brittle fracture

Ductile fracture

Electron microscopy

Failure (mechanical)

Ferrite

Fracture

Fracture mechanics

High resolution transmission electron microscopy

Nanostructures

Probes

Transmission electron microscopy

Atom-probe tomography

Cleavage fracture

Concentration fluctuation

Cr concentration

Fracture behaviour

Room temperature

Super duplex stainless steel

Stainless steel

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