scholarly journals Effect of Cooling Rate on the Formation of Nonmetallic Inclusions in X80 Pipeline Steel

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 392 ◽  
Author(s):  
Xianguang Zhang ◽  
Wen Yang ◽  
Haikun Xu ◽  
Lifeng Zhang
Keyword(s):  
Cooling Rate ◽  
Nonmetallic Inclusions ◽  
Pipeline Steel ◽  
Number Density ◽  
X80 Pipeline Steel ◽  
Stress Cracking ◽  
Inverse Results ◽  
Hydrogen Induced Cracking ◽  
Sulfide Stress ◽  
Sulfide Stress Cracking

Nonmetallic inclusions have a strong influence on the hydrogen-induced cracking (HIC) and sulfide stress cracking (SSC) in pipeline steels, which should be well controlled to improve the steel resistance to HIC and SSC. The effects of cooling rate on the formation of nonmetallic inclusions have been studied both experimentally and thermodynamically. It was found that the increasing cooling rate increased the number density and decreased the size of the inclusions, while the inverse results were obtained by decreasing the cooling rate. Furthermore, as the cooling rate decreased from 10 to 0.035 K/s, the inclusions were changed from Al2O3-CaO to Al2O3-CaO-MgO-CaS. At a high cooling rate, the reaction time is short and the inclusions cannot be completely transformed which should be mainly formed at high temperatures. While, at low cooling rate, the inclusions can be gradually transformed and tend to follow the equilibrium compositions.

Microstructural aspects of sulfide stress cracking in an API X-80 pipeline steel

1996 ◽  
Vol 27 (11) ◽  
pp. 3601-3611 ◽  
Author(s):  
H. F. López ◽  
R. Raghunath ◽  
J. L. Albarran ◽  
L. Martinez
Keyword(s):  
Pipeline Steel ◽  
Stress Cracking ◽  
Sulfide Stress ◽  
Sulfide Stress Cracking

Full Ring Evaluation of X70 Grade UOE Line Pipes for Sour Service

2012 ◽  
Author(s):  
Kenji Kobayashi ◽  
Tomohiko Omura ◽  
Masahiko Hamada ◽  
Hiroyuki Nagayama ◽  
Izuru Minato ◽  
...  
Keyword(s):  
Large Diameter ◽  
High Strength ◽  
Casting Process ◽  
Ring Test ◽  
Past Performance ◽  
Stress Cracking ◽  
Hydrogen Induced Cracking ◽  
Sulfide Stress ◽  
Sulfide Stress Cracking ◽  
Sour Service

High-strength large-diameter UOE line pipes over X70 grade are difficult to apply to actual fields, including H2S, because of a deterioration of sour resistance and a lack of past performance. However, API X70 grade large-diameter UOE line pipes for sour service have been manufactured stably by optimizing the continuous casting process, controlling the shape of inclusions and decreasing coarse precipitates. A full-ring test can simulate fairly well the actual applied conditions of line pipes and evaluate hydrogen induced cracking (HIC), sulfide stress cracking (SSC) and stress oriented hydrogen induced cracking (SOHIC) of line pipes for sour service simultaneously. It was confirmed that the X70 grade UOE line pipes have a good sour resistance from standard HIC tests, four-point bent beam SSC tests and the full-ring test including a seam weld under severe sour conditions (NACE solution A with 0.1 MPa H2S). In addition, the SSC resistance of a girth welded portion was also investigated by using simulated HAZ.

Relationship between hydrogen-induced cracking and type I sulfide stress cracking of high-strength linepipe steel

2010 ◽  
Vol 62 (4) ◽  
pp. 195-198 ◽  
Author(s):  
Wan Keun Kim ◽  
Hwan Gyo Jung ◽  
Gyu Tae Park ◽  
Seong Ung Koh ◽  
Kyoo Young Kim
Keyword(s):  
High Strength ◽  
Type I ◽  
Stress Cracking ◽  
Hydrogen Induced Cracking ◽  
Sulfide Stress ◽  
Sulfide Stress Cracking ◽  
Linepipe Steel

scholarly journals Effects of Alloying Elements (C, Mo) on Hydrogen Assisted Cracking Behaviors of A516-65 Steels in Sour Environments

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4188
Author(s):  
Jin Sung Park ◽  
Jin Woo Lee ◽  
Joong Ki Hwang ◽  
Sung Jin Kim
Keyword(s):  
Alloying Elements ◽  
Pressure Vessel Steel ◽  
Vessel Steel ◽  
Stress Cracking ◽  
Hydrogen Induced Cracking ◽  
Hydrogen Assisted Cracking ◽  
Sulfide Stress ◽  
Sulfide Stress Cracking ◽  
Mo Content ◽  
Kinetics Of

This study examined the effects of alloying elements (C, Mo) on hydrogen-induced cracking (HIC) and sulfide stress cracking (SSC) behaviors of A516-65 grade pressure vessel steel in sour environments. A range of experimental and analytical methods of HIC, SSC, electrochemical permeation, and immersion experiments were used. The steel with a higher C content had a larger fraction of banded pearlite, which acted as a reversible trap for hydrogen, and slower diffusion kinetics of hydrogen was obtained. In addition, a higher hardness in the mid-thickness regions of the steel, due to center segregation, resulted in easier HIC propagation. On the other hand, the steel with a higher Mo content showed more dispersed banded pearlite and a larger amount of irreversibly trapped hydrogen. Nevertheless, the addition of Mo to the steel can deteriorate the surface properties through localized pitting and the local detachment of corrosion products with uneven interfaces, increasing the vulnerability to SSC. The mechanistic reasons for the results are discussed, and a desirable alloy design for ensuring an enhanced resistance to hydrogen assisted cracking (HAC) is proposed.

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