Inclusion Characteristics and Acicular Ferrite Nucleation in Ti-Containing Weld Metals of X80 Pipeline Steel

2018 ◽  
Vol 49 (6) ◽  
pp. 2124-2138 ◽  
Author(s):  
Bingxin Wang ◽  
Xianghua Liu ◽  
Guodong Wang
Keyword(s):  
Acicular Ferrite ◽  
Pipeline Steel ◽  
X80 Pipeline Steel ◽  
Weld Metals ◽  
Ferrite Nucleation

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.

Acicular ferrite nucleation mechanism in laser-MAG hybrid welds of X100 pipeline steel

2021 ◽  
pp. 130603
Author(s):  
Xiaonan Qi ◽  
Xiaonan Wang ◽  
Hongshuang Di ◽  
Xinjun Shen ◽  
Pengcheng Huan ◽  
...  
Keyword(s):  
Acicular Ferrite ◽  
Pipeline Steel ◽  
Nucleation Mechanism ◽  
X100 Pipeline Steel ◽  
Ferrite Nucleation

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 Texture Comparison of an Acicular Ferrite Pipeline Steel with Different Hot Rolling Process

2011 ◽  
Vol 399-401 ◽  
pp. 264-267
Author(s):  
Hai Yan Wang ◽  
Hui Ping Ren ◽  
Le Han ◽  
Zi Li Jin ◽  
Hao Sun
Keyword(s):  
Hot Rolling ◽  
Acicular Ferrite ◽  
Pipeline Steel ◽  
Orientation Distribution ◽  
Rolling Process ◽  
X80 Pipeline Steel ◽  
Hot Rolling Process ◽  
X80 Steel ◽  
Hot Rolled ◽  
Electron Back Scattered Diffraction

Microstructure of X80 pipeline steel with different hot rolling process was compared using Optical microscopy (OM), Bulk X-ray texture and micro orientation analysis was carried out by Orientation distribution function (ODF) and Electron back-scattered diffraction (EBSD), to analyze the various texture components of the pipeline steels under two different rolling processes. The results show that the final microstructures under the two schedules both present typical acicular ferrite characteristic. On the other side, the corresponding textures were found mainly comprised of two fibers in the rolling and normal direction in hot rolled X80 steel plate, there were obvious {112} , {110} , and {111} fiber, which seemed to be related with the mechanical properties anisotropy. Therefore, the influences of the microstructure and texture on the anisotropy were also discussed in this paper.

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.

Study on Microstructure and Properties of X80 Pipeline Steel

2014 ◽  
Vol 941-944 ◽  
pp. 138-141 ◽  
Author(s):  
Xiang Dong Huo ◽  
Feng Dong ◽  
Lie Jun Li
Keyword(s):  
Grain Refinement ◽  
Impact Energy ◽  
Acicular Ferrite ◽  
Precipitation Hardening ◽  
Pipeline Steel ◽  
High Strength ◽  
Experimental Methods ◽  
Microstructural Characteristics ◽  
X80 Pipeline Steel ◽  
Toughness Improvement

Experimental methods, such as OM, SEM and X-EDS, were used to study the microstructure of X80 pipeline steel. It mainly consists of fine acicular ferrite (AF). X80 pipeline steel possesses high strength and impact energy at-30°C approaches to 400J. Grain refinement and precipitation hardening are the main reasons for high strength, and toughness improvement can be attributed to grain refinement and particular microstructural characteristics of AF.

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.

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