Microstructure and Mechanical Properties of Fiber Laser-Metal Active Gas Hybrid Weld of X80 Pipeline Steel

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Lei Zhenglong ◽  
Tan Caiwang ◽  
Chen Yanbin ◽  
Sun Zhongshao
Keyword(s):  
Fiber Laser ◽  
Acicular Ferrite ◽  
Pipeline Steel ◽  
Welding Process ◽  
Granular Bainite ◽  
Hybrid Welding ◽  
X80 Pipeline Steel ◽  
The Difference ◽  
Pipeline Welding ◽  
And Performance

Fiber laser-metal active gas (MAG) hybrid welding process was explored to join X80 pipeline steel to improve the efficiency and performance of pipeline welding. During the hybrid welding process, five different positions are applied to simulate the practical pipe girth welding. The weldability is evaluated concerning the bead shape, hardness, tensile, impact properties, and microstructures of welded joints. The results reveal that the tensile strength is higher than that of the base metal and the weld has a good impact ductility and an excellent bend performance. At the same time, the difference in microstructure between the laser zone and arc zone of laser-MAG hybrid welding of X80 pipeline steel is observed. Compared with the arc zone, the laser zone has finer weld grains and a narrower heat affected zone (HAZ). The fusion zone microstructure of the arc zone mainly consists of columnar proeutectoid ferrite (PF) and fine acicular ferrite (AF), whereas that of laser zone comprises acicular ferrite, upper bainite (Bu), and granular bainite (BG), which verifies technical feasibility of hybrid welding in pipeline steel and lays a good foundation for practical application.

Mechanical Properties and CO2 Corrosion Behavior of High Strength and Toughness X80 Pipeline Steel

2014 ◽  
Vol 1010-1012 ◽  
pp. 1709-1712
Author(s):  
Li Dong Wang ◽  
Feng Lei Liu ◽  
Hui Bin Wu
Keyword(s):  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Acicular Ferrite ◽  
Pipeline Steel ◽  
High Strength ◽  
Strengthening Mechanism ◽  
Granular Bainite ◽  
X80 Pipeline Steel ◽  
Better Than ◽  
Strength And Toughness

A type of X80 grade high strength and toughness pipeline steel was designed and researched. The strengthening mechanism of the steel was analyzed by SEM, TEM and XRD, and the CO2corrosion behavior of the steel was simulated by high-temperature and high-pressure autoclave. The result shows that the microstructure of the base metal is mainly acicular ferrite with a small amount of granular bainite. Acicular ferrite consists of laths which occlude and interweave with each other, and there are many dislocation and carbonitrides distributing in acicular ferrite, which made the pipeline steel have good strength and toughness. Under the simulation of the actual working conditions, the activity of reactants is low at 30°C, so the corrosion rate is smaller at this temperature; the maximum of corrosion rate occurs at 60°C; when the temperature increases to 90°C, the corrosion rate is lower than that of 60°C, that is because hindering corrosion effect which take by the acceleration deposit of corrosion product is better than the acceleration corrosion reactions.

Microstructure and Mechanical Properties of X80 Pipeline Steel Backing Welded Joint by Fiber Laser-MAG Hybrid Welding

2013 ◽  
Vol 40 (4) ◽  
pp. 0403002
Author(s):  
雷正龙 Lei Zhenglong ◽  
檀财旺 Tan Caiwang ◽  
陈彦宾 Chen Yanbin ◽  
刘德健 Liu Dejian ◽  
胡席远 Hu Xiyuan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fiber Laser ◽  
Welded Joint ◽  
Pipeline Steel ◽  
Hybrid Welding ◽  
X80 Pipeline Steel ◽  
Microstructure And Mechanical Properties

The Toughness Index of X80 Mother Linepipe Steel and Its Optimum Microstructure

2008 ◽  
Author(s):  
Xiaoli Zhang ◽  
Yaorong Feng ◽  
Yinglai Liu ◽  
Chuanjing Zhuang
Keyword(s):  
Experimental Data ◽  
Acicular Ferrite ◽  
Pipeline Steel ◽  
Granular Bainite ◽  
X80 Pipeline Steel ◽  
Type Steel ◽  
Toughness Index ◽  
X80 Steel ◽  
Linepipe Steel ◽  
Selection Of

Large amount of experimental data indicated, that the index of CVN toughness and shearing area of mother pipe of X80 are (200J, 90%). And the results showed that when charpy toughness was closing to 200J, the shearing area would reach to 90%; when the charpy toughness increased continuously, the shearing area would not increase further more. So the selection of charpy toughness value as 200J for pipeline steels is reasonable, and also its corresponding shearing area. To gain thus component index, the optimum microstructure of X80 steel should be strip-like ferrite mastered, small amount of granular bainite contained-acicular ferrite type steel, and, in which the size of MA island should be less than 1μm. This kinds of optimum microstructure of X80 pipeline steel will exert its softening role in improving toughness and simultaneity not decrease its strength.

Fracture Toughness of Different Locations in API X80 Pipeline Steel on Low Constraint SENT Specimens

2016 ◽  
Vol 853 ◽  
pp. 251-255
Author(s):  
Hong Sheng Lu ◽  
Yong He Yang ◽  
Gang Chen ◽  
Xu Chen ◽  
Xin Wang
Keyword(s):  
Welded Joints ◽  
Weak Link ◽  
Pipeline Steel ◽  
Welding Process ◽  
Resistance Curve ◽  
X80 Pipeline Steel ◽  
Three Samples ◽  
Inner Surface ◽  
Notch Orientation ◽  
Low Constraint

With the considerable use of high-grade pipeline steel in onshore and offshore project, welded joints are recognized as the weak link in pipeline because of the non-uniform microstructural regions induced by welding heat input. At first, the microstructural of different regions in API X80 pipeline welded joints was characterized and quantified by SEM, which indicate that the pipeline steel is a typical acicular ferrite steel. In this paper we investigated the J-integral resistance curve (J-R curve) in different locations of API X80 pipeline welded joints through low constraint SENT specimens with side grooves at room temperature. The effect of notch orientation (longitudinal-radial (L-R) and transverse-radial (T-R)) on resistance curve were investigated in base metal, which reveal the orientation almost have no effect on resistance curve. As the welded joints adopted in this study is two-pass steel arc welds, so the J-R curves of the inner surface, the outer surface and through-thickness surface notches specimens in the weld metal were investigated. The inner surface sample have the highest toughness through three samples because of the effect of second pass welding process. The effect of constraint on resistance curve was conduct between low constraint SENT specimen and high constraint SENB specimen, which found that the lower constraint corresponding to the higher resistance curve. After finishing the test, crack advancing plan of different positions were etched and observed by OM to demonstrate that the crack path always in the region which we would like to test.

Fiber Laser-TIG Hybrid Welding Process of 316 Stainless Steel Plate

Applied laser ◽  
2014 ◽  
Vol 34 (1) ◽  
pp. 46-50
Author(s):  
尹燕 Yin Yan ◽  
曾智 Zeng Zhi ◽  
他进国 Ta Jinguo ◽  
王占冲 Wang Zhanchong ◽  
张瑞华 Zhang Ruihua
Keyword(s):  
Stainless Steel ◽  
Fiber Laser ◽  
Steel Plate ◽  
Welding Process ◽  
Hybrid Welding ◽  
Stainless Steel Plate ◽  
316 Stainless Steel

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.

scholarly journals Effect of Tempering Temperature after Thermo-Mechanical Control Process on Microstructure Characteristics and Hydrogen-Induced Ductility Loss in High-Vanadium X80 Pipeline Steel

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2839
Author(s):  
Longfei Li ◽  
Bo Song ◽  
Biwen Yang ◽  
Lei Wang ◽  
Wensen Cheng
Keyword(s):  
Hydrogen Diffusion ◽  
Pipeline Steel ◽  
Control Process ◽  
Granular Bainite ◽  
X80 Pipeline Steel ◽  
Tempering Temperature ◽  
Mechanical Control ◽  
Ductility Loss ◽  
Vanadium Carbides ◽  
20 Nm

In this study, an optimum tempering temperature after a thermo-mechanical control process (TMCP) was proposed to improve the hydrogen-induced ductility loss of high-vanadium X80 pipeline steel. The results showed that with increasing tempering temperature from 450 to 650 °C, the size and quantity of granular bainite decreased but the spacing of deformed lath ferrite and the fraction of massive ferrite increased. The number of fine vanadium carbides increased as well. However, as the tempering temperature increased to 700 °C, the microstructure of T700 steel completely converted to massive ferrite and the grain size became larger. Additionally, the amount of nanoscale precipitates decreased again, and the mean size of precipitates evidently increased in T700 steel. The steel tempering at 650 °C, containing the most vanadium precipitates with a size less than 20 nm, had the lowest hydrogen diffusion coefficient and the best resistance to hydrogen-induced ductility loss.

Continuous Cooling Phase Transformation Rules of High Nb X80 Pipeline Steel

2016 ◽  
Vol 850 ◽  
pp. 916-921
Author(s):  
Pei Pei Xia ◽  
Liu Qing Yang ◽  
Xiao Jiang Guo ◽  
Ye Zheng Li
Keyword(s):  
Phase Transformation ◽  
Cooling Rate ◽  
Acicular Ferrite ◽  
Thermal Deformation ◽  
Pipeline Steel ◽  
Phase Transformation Temperature ◽  
X80 Pipeline Steel ◽  
Continuous Cooling ◽  
Simulation Testing ◽  
Cooling Phase

The microstructural evolution of the high Nb X80 pipeline steel in Continuous Cooling Transformation (CCT) by Gleeble-3500HS thermal mechanical simulation testing system was studied, the corresponding CCT curves were drawn and the influence of some parameters such as deformation and cooling rate on microstructure of high Nb X80 pipeline steel was analyzed. The results show that as cooling rate increased, the phase transformation temperature of high Nb X80 steel decreased, with the microstructure transformation from ferrite-pearlite to acicular ferrite and bainite-ferrite. When cooling rate was between 20°C/s and 30°C/s, the microstructure was comparatively ideal acicular ferrite, thermal deformation accelerates phase transformation notably and made the dynamic CCT curves move upward and the initial temperature of phase transformation increase obviously. Meanwhile the thermal deformation refined acicular ferrite and extended the range of cooling rate accessible to acicular ferrite.

Effects of Cooling Processes on Microstructure Evolution of X80 Pipeline Steel

2014 ◽  
Vol 788 ◽  
pp. 378-383 ◽  
Author(s):  
Feng Qin Ji ◽  
Guo Dong Wang
Keyword(s):  
Low Temperature ◽  
Pipeline Steel ◽  
Bainitic Ferrite ◽  
Development Trend ◽  
Optical Microscope ◽  
Granular Bainite ◽  
X80 Pipeline Steel ◽  
Pipeline Steels ◽  
Low Temperature Toughness ◽  
Strength And Plasticity

With the development of pipeline industry, the pipeline steels with higher strength and plasticity, better low-temperature toughness and weldability are the main development trend. For bainitic pipeline steels, M/A constituent is the main hard phase. Although the M/A constituent can enhance the strength, the larger block-form M/A constituent can deteriorate low-temperature toughness. Therefore, it is essential to further investigate how to refine the M/A constituent. In the present paper, X80 pipeline steel was cooled to room temperature with various cooling paths after hot compression deformation at the temperature of 800oC. The evolution of microstructure of X80 pipeline steel has been analyzed by optical microscope (OM) and scanning electron microscope (SEM). The experimental results show that increasing the cooling rate can significantly refine M/A constituent and promote the formation of granular bainite, and the bainitic ferrite can be also greatly refined. In addition, the effects of five final temperatures of fast cooling were also investigated.

Improvement in Ovality of Pipeline Steel X80 with Weld Power under Multi-Wire SAW Welding Process

2011 ◽  
Vol 239-242 ◽  
pp. 1823-1831 ◽  
Author(s):  
Yi Bo Li ◽  
Ming Hui Huang ◽  
Xin Jiang Lu
Keyword(s):  
Oil And Gas ◽  
Pipeline Steel ◽  
Welding Process ◽  
Element Model ◽  
Simulation Method ◽  
Source Model ◽  
Long Distance ◽  
X80 Pipeline Steel ◽  
Wire Saw ◽  
Welding Processes

Pipeline steel X80 is a kind of advanced high grade steel and commonly used in long-distance transportation of oil and gas. Ovality of the pipe plays key role in improving its crushing strength. In this paper, a simulation method is proposed to improve the performance of ovality of X80 Pipeline Steel. First, a 3D thermo-mechanical coupled finite element model of the multi-wire SAW welding processes is built using MSC.MARC, upon which parameters of double ellipsoid heat source model is determined. Then, the relationship between weld power and ovality is studied under difference process inputs and a satisfactory weld power is found to decrease the ovality of the pipeline steel. Finally, validation and prediction of deformation and ovality of the pipeline is carried out via plate welding experiments.

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