TY - GEN
T1 - Evaluation of weld metal hydrogen cracking risk in a 2.25Cr-1Mo-0.25V-TiB (T24) boiler steel
AU - Nevasmaa, Pekka
AU - Laukkanen, Anssi
AU - Häkkilä, Juha
PY - 2004
Y1 - 2004
N2 - Standardised methods for the assessment of hydrogen
cracking risk are mostly developed for HAZ cracking
cases, where cracking often occurs as root cracking. The
applied experiments are therefore usually single-pass
cracking tests. For multiple-pass welding, and when the
cracking sensitivity of weld metal dictates the required
preheat, European standards do not give reliable guidance
on how to assess the need of preheat. Standard EN 1011-2
considers the possibility of weld metal cracking,
however, it does not provide the user with a validated
methodology for the calculation of the actual level of
'safe' preheat temperature. The suitability of a given
standard procedure, or calculation method, for multipass
welds therefore has to be investigated on case by case
basis. This paper is concerned with the assessment of
required preheat/interpass temperature for the avoidance
of hydrogen cracking in matching type multipass weld
metal in a 2.25%Cr-1.0%Mo-0.25%V boiler steel using
experimental and numerical methods. The applied methods
were: (i) EN 1011-2 Method, (ii) Crack no crack diagram
method developed by VTT, and (iii) deep-notch Implant
test based analytical method developed by Osaka
University and VTT. Necessary precautions for safe
welding are given. Recent developments in numerical
modelling of hydrogen diffusion in multipass welding are
discussed.
AB - Standardised methods for the assessment of hydrogen
cracking risk are mostly developed for HAZ cracking
cases, where cracking often occurs as root cracking. The
applied experiments are therefore usually single-pass
cracking tests. For multiple-pass welding, and when the
cracking sensitivity of weld metal dictates the required
preheat, European standards do not give reliable guidance
on how to assess the need of preheat. Standard EN 1011-2
considers the possibility of weld metal cracking,
however, it does not provide the user with a validated
methodology for the calculation of the actual level of
'safe' preheat temperature. The suitability of a given
standard procedure, or calculation method, for multipass
welds therefore has to be investigated on case by case
basis. This paper is concerned with the assessment of
required preheat/interpass temperature for the avoidance
of hydrogen cracking in matching type multipass weld
metal in a 2.25%Cr-1.0%Mo-0.25%V boiler steel using
experimental and numerical methods. The applied methods
were: (i) EN 1011-2 Method, (ii) Crack no crack diagram
method developed by VTT, and (iii) deep-notch Implant
test based analytical method developed by Osaka
University and VTT. Necessary precautions for safe
welding are given. Recent developments in numerical
modelling of hydrogen diffusion in multipass welding are
discussed.
KW - ProperTune
M3 - Conference article in proceedings
SN - 951-38-6293-3
T3 - VTT Symposium
SP - 393
EP - 407
BT - BALTICA VI - Life Management and Maintenance for P ower Plants. Vol. 2
PB - VTT Technical Research Centre of Finland
T2 - BALTICA VI - Life Management and Maintenance for Power Plants
Y2 - 8 June 2004 through 10 June 2004
ER -