TY - GEN
T1 - Thermal ageing of ferrite in stainless steel
AU - Nenonen, Pertti
N1 - Project code: H2SU00363
PY - 2003
Y1 - 2003
N2 - The changes in the microstructure and composition of
ferrite in two types of cast duplex stainless steels and
in an austenitic-ferritic weld metal after long term
thermal ageing has been studied using analytical
transmission electron microscope (FEGTEM). A cast test
steel containing Mo was investigated first as a reference
material in three different conditions: as solution
annealed, aged at 300oC and aged at 400oC. This
investigation was carried out to gain experience of how
EDS analyser and TEM can bee used to study elemental
unhomogeneity, which is usually investigated with an atom
probe (APFIM). The two other materials, an
austenitic-ferritic weld metal and a cast duplex
Ti-stabilised stainless steel used for long time at NPP
operation temperature were investigated using the
experience obtained with the test steel.
The results showed that analytical TEM can be used to
investigate elemental unhomogeneity of ferrite, but there
are several important things to be taken into account
when the spectra for this purpose are collected. These
kind of things are, such as the thickness of the
specimen, probe size, contamination rate, "elemental
background" of the spectrum and possible enrichment of
certain alloying elements in the surface oxide layer of
the TEM-specimens. If minor elements are also analysed,
it may increase the scattering of the results.
AB - The changes in the microstructure and composition of
ferrite in two types of cast duplex stainless steels and
in an austenitic-ferritic weld metal after long term
thermal ageing has been studied using analytical
transmission electron microscope (FEGTEM). A cast test
steel containing Mo was investigated first as a reference
material in three different conditions: as solution
annealed, aged at 300oC and aged at 400oC. This
investigation was carried out to gain experience of how
EDS analyser and TEM can bee used to study elemental
unhomogeneity, which is usually investigated with an atom
probe (APFIM). The two other materials, an
austenitic-ferritic weld metal and a cast duplex
Ti-stabilised stainless steel used for long time at NPP
operation temperature were investigated using the
experience obtained with the test steel.
The results showed that analytical TEM can be used to
investigate elemental unhomogeneity of ferrite, but there
are several important things to be taken into account
when the spectra for this purpose are collected. These
kind of things are, such as the thickness of the
specimen, probe size, contamination rate, "elemental
background" of the spectrum and possible enrichment of
certain alloying elements in the surface oxide layer of
the TEM-specimens. If minor elements are also analysed,
it may increase the scattering of the results.
M3 - Conference article in proceedings
SN - 951-38-6280-1
T3 - VTT Symposium
SP - 253
EP - 275
BT - Plant Life Management
PB - VTT Technical Research Centre of Finland
CY - Espoo
T2 - Plant Life Management
Y2 - 1 January 2002 through 1 January 2002
ER -