A laboratory smelted micro-alloyed pipeline steel with chemical composition of C 0.025 %, Mn 1.56 %, Si 0.24%, Nb 0.04 %, V 0.02%, Mo 0.32%, S 0.0006 %, P 0.002%, O 0.0043%, N 0.0062 % was directly cooled to room temperature at 20 TVs, or was cooled at the same cooling rate to 400 deg C and hold for 1 h in a 500 deg C furnace and then furnace-cooled to room temperature. As a result, two different microstructures, i.e., ultra-fine ferrite and acicular ferrite, were obtained. The results of hydrogen induced cracking (HIC) testing according to NACE TM0284-96 and sulfide stress cracking (SSC) testing according to Method B-NACE TM0177-96 showed that these two microstructures are both insusceptible to HIC and possesses superior SSC resistance than those of the commercial ferrite-pearlite pipeline steels. Furthermore, the SSC resistant behaviors of acicular ferrite were higher than those of ultra-fine ferrite, which might be attributed to the hydrogen traps caused by the dispersed precipitates of carbon-nitrides as well as the high density tangled dislocation.
Comparison on anti-H2S behaviors of micro-alloyed pipeline steels with acicular ferrite and ultrafine ferrite
2002
6 Seiten, 4 Bilder, 4 Tabellen, 19 Quellen
Conference paper
English
Lath boundary thin-film martensite in acicular ferrite ultralow carbon pipeline steels
Tema Archive | 2005
|Engineering Index Backfile | 1946