Creep, strain and oxidation damage in the ferritic ductile cast iron SiMo51 at 700°C

• The ferritic ductile cast iron, SiMo51, with graphite nodules and grain boundary carbides, was tested at 700°C with respect to creep, uniaxial strain and oxidation, investigating the internal damage evolution. Creep curves, with total lives of 65–339 days, show a short primary creep followed by predominantly tertiary creep displaying two stages. The first was associated with cavitation around carbides and nodules with a short initial effect from oxidation. The second was associated with the formation of cracks through linking of elongated voids. Misorientation maps demonstrate local dislocation activity during creep and tensile testing. Oxidation tests, between 15 min and 2 weeks, show that three oxide layers are formed and that an innermost precipitation zone of SiO2 is present in the initial stage. Elemental line scans, compared with thermodynamic calculations, suggest the layers are FeO with precipitates of SiO2 and/or Fe2SiO4, FeO without precipitates, and Fe2O3.

Ämnesord

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

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

Nyckelord

Creep

ductile cast iron

EBSD

oxidation

tensile test

Carbides

Creep testing

Ferrite

Grain boundaries

Hematite

Internal oxidation

Molybdenum compounds

Silica

Silicon

Tensile testing

Dislocation activity

Ductile cast irons

Grain boundary carbides

Internal damages

Oxidation damage

Thermodynamic calculations

Uni-axial strains

Cast iron

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)