Evaluation of the fracture toughness of X70 pipeline steel with ferrite-bainite microstructure

2017 ◽  
Vol 688 ◽  
pp. 388-395 ◽  
Author(s):  
Liu Ligang ◽  
Xiao Hong ◽  
Li Qiang ◽  
Liu Yu ◽  
Li Peishuai ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Pipeline Steel ◽  
X70 Pipeline Steel ◽  
Bainite Microstructure

Forming mechanism of delamination cracks observed during tensile and fracture toughness testing of X70 pipeline steel

2017 ◽  
Vol 209 (1-2) ◽  
pp. 223-229 ◽  
Author(s):  
Dong-Yeob Park ◽  
Babak Shalchi Amirkhiz ◽  
Jean-Philippe Gravel ◽  
Jie Liang ◽  
Renata Zavadil ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Pipeline Steel ◽  
X70 Pipeline Steel ◽  
Forming Mechanism ◽  
Fracture Toughness Testing ◽  
Toughness Testing ◽  
Delamination Cracks

Microstructure and Mechanical Properties Analysis of X70 Pipeline Steel with Polygonal Ferrite Plus Granular Bainite Microstructure

2012 ◽  
Vol 161 ◽  
pp. 67-71 ◽  
Author(s):  
Zhan Zhan Zhang ◽  
Xiu Rong Zuo ◽  
Yue Yue Hu ◽  
Ru Tao Li ◽  
Zhi Ming Zhang
Keyword(s):  
Mechanical Properties ◽  
Pipeline Steel ◽  
High Strength ◽  
Polygonal Ferrite ◽  
Granular Bainite ◽  
X70 Pipeline Steel ◽  
Microstructure And Mechanical Properties ◽  
Drop Weight ◽  
Bainite Microstructure ◽  
Strength And Toughness

Microstructure and mechanical properties of X70 pipeline steel with polygonal ferrite plus granular bainite were characterized using tensile tests, Charpy V-notch impact tests, drop weight tear tests, hardness tests and scanning electron microscopy. The results of experiment indicated that X70 pipeline steel with polygonal ferrite plus granular bainite showed an excellent combination of high strength and toughness. The base metal with polygonal ferrite plus granular bainite microstructure exhibited perfect mechanical properties in terms of the transverse yield ratio of 0.81, elongation of 46%, an impact energy of 335 J at -10 °C and a shear area of 90% at 0 °C in the drop weight tear test. The heat affected zone contained coarse grain zone and fine grain zone, which exhibited good low temperature toughness of 216 J at -10 °C. The weld metal primarily consisted of intragranularly nucleated acicular ferrites which led to the high strength and toughness.

Research of the DWTT Fracture of X70 Pipeline Steel

2012 ◽  
Vol 535-537 ◽  
pp. 643-646
Author(s):  
Ying Sun
Keyword(s):  
Fracture Toughness ◽  
Grain Size ◽  
Pipeline Steel ◽  
Polygonal Ferrite ◽  
Ferrite Content ◽  
X70 Pipeline Steel ◽  
The Difference ◽  
Shear Area ◽  
Area Percentage ◽  
Different Content

The DWTT fracture toughness of X70 pipeline steel with different content and grain size of polygonal ferrite was investigated. The results show that when the content of polygon ferrite is above 28%, the shear-area percentage of DWTT fracture begins to decrease instead of increase, while polygonal ferrite toughening effect weakens. It is the difference of the polygonal ferrite content that results in the difference of shear-area percentage of DWTT fracture.

STRESS CORROSION CRACK INITIATION BEHAVIOR FOR THE X70 PIPELINE STEEL BENEATH A DISBONDED COATING

2012 ◽  
Vol 48 (10) ◽  
pp. 1267 ◽  
Author(s):  
Zhiying WANG ◽  
Jianqiu WANG ◽  
En-hou HAN ◽  
Wei KE ◽  
Maocheng YAN ◽  
...  
Keyword(s):  
Crack Initiation ◽  
Stress Corrosion ◽  
Stress Corrosion Crack ◽  
Pipeline Steel ◽  
X70 Pipeline Steel ◽  
Disbonded Coating

Corrosion Behavior of X70 Pipeline Steel and Corrosion Rate Prediction Under the Combination of Corrosive Medium and Applied Pressure

2017 ◽  
Author(s):  
Kaikai Li ◽  
Wei Wu ◽  
Guangxu Cheng ◽  
Yun Li ◽  
Haijun Hu ◽  
...  
Keyword(s):  
Natural Gas ◽  
Corrosion Rate ◽  
Tensile Stress ◽  
Partial Pressure ◽  
Corrosion Behavior ◽  
Pipeline Steel ◽  
Applied Pressure ◽  
Chloride Concentration ◽  
X70 Pipeline Steel ◽  
Co2 Partial Pressure

Natural gas transmission pipeline is prone to internal corrosion due to the combination of corrosive impurities in the pipe (such as CO2, H2S and chlorides) and applied pressure of the pipeline, which seriously affects the safe operation of the pipeline. In this work, the corrosion behavior of a typical X70 pipeline steel was investigated by using potentiodynamic polarization and electrochemical impendence spectroscopy (EIS). The polarization and EIS data under different CO2 partial pressures (0–1 atm), H2S concentrations (0–150 ppm), chloride concentrations (0–3.5 wt%) and tensile stress (0–400 MPa) were obtained. The results show that corrosion rate increases with the increase of CO2 partial pressure and chloride concentration, respectively, while first increases and then decreases with the increase H2S concentrations. The corrosion rate is less affected by elastic tensile stress. In addition, a quantitative prediction model for corrosion rate of natural gas pipeline based on adaptive neuro-fuzzy inference system (ANFIS) was established by fitting the experimental data which maps the relationship between the key influencing factors (i.e. CO2 partial pressure, H2S concentration, chloride concentration and tensile stress) and the corrosion rate. The prediction results show that the relative percentage errors of the predicted and experimental values are relatively small. The prediction accuracy of the model satisfies the engineering application requirement.

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