Sammendrag
The risk of brittle fracture is an important aspect when oil and gas
exploration move to Arctic regions. Therefore, the present work
addresses examination of fracture surfaces in scanning electron
microscope to identify brittle fracture mechanisms. The study is based
on Charpy and CTOD bend testing at -60 °C of weld thermal simulated
specimens corresponding to both coarse grained HAZ (CGHAZ) and
intercritically reheated coarse grained HAZ (ICCGHAZ). Brittle
fracture was obtained by both test methods, and SEM investigation of
the fracture surfaces revealed that slag particles like sulphides and
oxides had initiated cleavage in the CGHAZ specimens, and that
martensite-austenite (MA) particles probably were responsible for
cleavage in the ICCGHAZ specimens. In both types of weld simulated
structures, the crack initiation points were located close to the pre-crack
tip.
exploration move to Arctic regions. Therefore, the present work
addresses examination of fracture surfaces in scanning electron
microscope to identify brittle fracture mechanisms. The study is based
on Charpy and CTOD bend testing at -60 °C of weld thermal simulated
specimens corresponding to both coarse grained HAZ (CGHAZ) and
intercritically reheated coarse grained HAZ (ICCGHAZ). Brittle
fracture was obtained by both test methods, and SEM investigation of
the fracture surfaces revealed that slag particles like sulphides and
oxides had initiated cleavage in the CGHAZ specimens, and that
martensite-austenite (MA) particles probably were responsible for
cleavage in the ICCGHAZ specimens. In both types of weld simulated
structures, the crack initiation points were located close to the pre-crack
tip.