The sour gas susceptibility of X-80 steel was investigated after quenching and tempering. Self-loaded modified wedge opening loading (M-WOL) specimens were exposed to an NACE sour gas solution under an applied opening mode stress intensity factor KI of 40 MPa m1/2. In this microstructural condition, crack arrest was exhibited at a threshold stress intensity value KISSC of 32 MPa m1/2. The relatively good performance of the steel after quenching and tempering was closely related to the development of a fine distribution of (Nb, Ti) containing carbides along ferrite lath boundaries. Apparently, the main crack path exhibited a significant number of bifurcations as it shifted continuously to follow the ferrite interlath boundaries as well as the prior austenitic grain boundaries. The crack paths developed were observed under a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectrometer (EDX). In addition, transmission electron microscopy (TEM) was used for microstructural observations of the crack tip regions. The microstructure of pipeline steel is much better indicator of resistance of cracking in sour environments than the hardness value. The resistance of API X-80 steel to sulfide stress cracking can be improved by microstructural modification through water quenching from the annealing temperature (852 deg C) and tempering at 600 deg C for 1 hr.
Improved sour gas resistance of X-80 steel after quenching and tempering
Verbesserte Beständigkeit von Stahl X-80 in Sauergas nach Abschrecken und Altern
British Corrosion Journal ; 33 , 3 ; 202-205
1998
4 Seiten, 5 Bilder, 1 Tabelle, 14 Quellen
Aufsatz (Zeitschrift)
Englisch
Improved Sour Gasoline Resistance of Epichlorohydrin Elastomer Fuel Hose
SAE Technical Papers | 1979
|Improved Sour Gasoline Resistance of Epichlorhydrin Elastomer Fuel Hose
Kraftfahrwesen | 1979
|Engineering Index Backfile | 1904