Microstructure and Toughness Properties of Subcritically, Intercritically and Supercritically Heat Affected Zones in X80 Pipeline Steel

2010 ◽  
Vol 154-155 ◽  
pp. 1850-1854 ◽  
Author(s):  
Sadegh Moeinifar
Keyword(s):  
Pipeline Steel ◽  
Charpy Impact ◽  
Initiation Site ◽  
Impact Testing ◽  
Peak Temperature ◽  
Coarse Grained ◽  
X80 Pipeline Steel ◽  
Brittle Phase ◽  
Charpy Impact Testing ◽  
Second Peak

The objective of this paper is to study the influence of second peak temperature during simulated welding on properties of the subcritically (S), intercritically (IC) and supercritically (SC) reheated coarse grained heat affected (CGHAZ) zones. This involved heating to a first peak temperature (TP1) of 1400 °C, then reheating to different second peak temperatures (TP2) of 700, 800 and 900 °C with a constant cooling rate of 3.75 °C/s. Toughness of the simulated reheated CGHAZ regions were assessed using Charpy impact testing at 0 and -50 °C. The blocky and connected M/A particles, along prior-austenite grain boundaries, act as a brittle phase for the initiation site of the brittle fracture. Charpy impact results indicated that IC CGHAZ had less absorbed energy with higher transition temperature and hardness.

Microstructure and Toughness Properties of Subcritically, Intercritically and Supercritically Heat Affected Zones in X80 Microalloyed Pipeline Steel

2011 ◽  
Vol 383-390 ◽  
pp. 5886-5893
Author(s):  
Sadegh Moeinifar
Keyword(s):  
Heat Affected Zone ◽  
Prior Austenite ◽  
Charpy Impact ◽  
Impact Testing ◽  
Peak Temperature ◽  
Coarse Grained ◽  
Secondary Peak ◽  
Thermal Cycles ◽  
Austenite Grain ◽  
Prior Austenite Grain

The influence of the real and simulated thermal cycles with different secondary peak temperatures on the properties of the reheated coarse grained heat affected zone (CGHAZ) in the X80 microalloyed steel has been investigated. The four wires tandem submerged arc welding process with different heat input values was used to generate real double passes thermal cycles. The simulated thermal cycles involved heating to the first peak temperature (TP1) of 1400 °C and then reheating to different secondary peak temperatures (TP2) of 700, 800 and 900 °C with cooling rates of 3.75 and 2 °C/s. The toughness of the simulated reheated CGHAZ with different peak temperature was assessed using Charpy impact testing at 0 °C and -50 °C. It is clear that the reheated CGHAZ thermal cycles with different second peak temperatures have a significant effect on morphology of the martensite/austenite (M/A) constituent. The blocky and connected M/A constituent along the prior-austenite grain boundaries as a brittle phase for crack initiation. The Charpy impact results indicated that intercritically reheated coarse grained heat affected zone had less absorbed energy with higher transition temperature and hardness. In the same prior-austenite grain size, cycles 2 and 4 with lower cooling rate (2 °C/s) have larger size of M/A constituents. The M/A constituent size such as mean diameter and length are important factors influencing Charpy impact properties of the simulated reheated CGHAZ.

Alfa fibers for Cereplast bio-composites reinforcement: Effects of chemical and biological treatments on the mechanical properties

2021 ◽  
pp. 096739112110060
Author(s):  
Mouna Werchefani ◽  
Catherine Lacoste ◽  
Hafedh Belguith ◽  
Chedly Bradai
Keyword(s):  
Charpy Impact ◽  
Impact Testing ◽  
Hot Water ◽  
Cellulose Content ◽  
Twin Screw ◽  
Electron Microscopy Analysis ◽  
Alfa Fibers ◽  
Charpy Impact Testing ◽  
Water Treatments ◽  
The Impact

The present work is a comparative study of the impact of Alfa fiber modifications on the Cereplast composites mechanical behavior. Various treatments have been employed, including mechanical, soda, saltwater-retting, hot-water treatments and enzymatic treatment using xylanase. Chemical and morphological analyses were carried out in order to determine the changes of the biochemical composition and the dimensions of fibers. Cereplast composites reinforced with Alfa fibers were fabricated using a twin-screw extrusion followed by an injection molding technique with a fiber load of 20 wt. %. Resulting materials were assessed by means of tensile, flexural and Charpy impact testing. Scanning Electron Microscopy analysis was carried out to investigate the interfacial properties of the composites. The results have shown a significant enhancement of mechanical strengths and rigidities for the xylanase-treated fiber composites, owing to the increase of cellulose content, the enhancement of defibrillation level and the improvement of matrix-fiber adhesion. The data proved that the technology of enzymes can be used as a powerful and eco-friendly approach to modify fiber surfaces and to increase their potential of reinforcement.

Charpy Impact Testing at 20°K

1965 ◽  
pp. 56-62 ◽  
Author(s):  
T. F. Kiefer ◽  
R. D. Keys ◽  
F. R. Schwartzberg
Keyword(s):  
Charpy Impact ◽  
Impact Testing ◽  
Charpy Impact Testing

Microstructure - Texture Related Toughness Anisotropy of API-X80 Pipeline Steel Characterized by Means of 3D-EBSD Technique

2007 ◽  
Vol 558-559 ◽  
pp. 1429-1434 ◽  
Author(s):  
Roumen H. Petrov ◽  
Orlando León García ◽  
Nuria Sánchez Mouriño ◽  
Leo Kestens ◽  
Jin Ho Bae ◽  
...  
Keyword(s):  
Grain Shape ◽  
Pipeline Steel ◽  
Rolling Direction ◽  
Charpy Impact ◽  
Shape Reconstruction ◽  
Rolled Plate ◽  
X80 Pipeline Steel ◽  
Standard Size ◽  
Industrial Grade ◽  
Ebsd Technique

The variations of in plane Charpy toughness anisotropy as a function of the microstructure and texture of an industrial grade of API –X80 pipeline steel was studied. Standard size Charpy samples with a long axis orientated at 0, 22.5, 45, 67.5 and 90° with respect to the rolling direction of the plate were tested at different temperatures varying from -196°C to 20°C. Microstructure and texture of the plates were investigated by means of electron backscattering diffraction (EBSD), XRD and the recently developed 3D EBSD technique. The spatial grain shape orientation distribution was examined on samples which were cut from the middle thickness of an industrial rolled plate by means of 3D EBSD and following grain shape reconstruction and approximation of the grain shape with ellipsoids. It was found that the experimentally observed 3D microstructures could well be correlated to the anisotropy of the measured Charpy impact toughness of the steel for the Charpy samples. The Charpy toughness anisotropy of the plates in the transition region where both ductile and brittle fractures take place can be related to the microstructural anisotropy characterized by the grain shape orientation and the spatial distribution of the 2nd phase.

scholarly journals Microstructure and Corrosion Resistance to H2S in the Welded Joints of X80 Pipeline Steel

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1325 ◽  
Author(s):  
Jian-Bao Wang ◽  
Guang-Chun Xiao ◽  
Wei Zhao ◽  
Bing-Rong Zhang ◽  
Wei-Feng Rao
Keyword(s):  
Corrosion Resistance ◽  
Heat Affected Zone ◽  
Welded Joints ◽  
Electrochemical Impedance ◽  
Pipeline Steel ◽  
Electrochemical Corrosion ◽  
Open Circuit ◽  
Coarse Grained ◽  
Granular Bainite ◽  
X80 Pipeline Steel

The microstructure and corrosion resistance in H2S environments for various zones of X80 pipeline steel submerged arc welded joints were studied. The main microstructures in the base metal (BM), welded metal (WM), coarse-grained heat-affected zone (CGHAZ), and fine-grained heat-affected zone (FGHAZ) were mainly polygonal ferrite and granular bainite; acicular ferrite with fine grains; granular bainite, ferrite, and martensite/austenite constituents, respectively. The corrosion behavior differences resulted from the microstructure gradients. The results of the micro-morphologies of the corrosion product films and the electrochemical corrosion characteristics in H2S environments, including open circuit potential and electrochemical impedance spectroscopy, showed that the order of corrosion resistance was FGHAZ > BM > WM > CGHAZ.

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