Research and Development Into Low Temperature Toughness of Large Diameter Heavy Wall X80 Pipeline Steel at Shougang Steel

2012 ◽  
Author(s):  
Wenhua Ding ◽  
Zhonghang Jiang ◽  
Jiading Li ◽  
Shaopo Li ◽  
Chunhe Zha ◽  
...  
Keyword(s):  
Low Temperature ◽  
Research And Development ◽  
Oil And Gas ◽  
Volume Fraction ◽  
Pipeline Steel ◽  
Large Diameter ◽  
X80 Pipeline Steel ◽  
Low Temperature Toughness ◽  
Process Strategy ◽  
Rough Rolling

In recent years the trend in oil and gas transmission pipelines has been toward higher operating pressures. This trend, while the desire to keep steel costs low, has resulted in an increased demand for large diameter heavy wall X80 with good low temperature toughness. It is well known that improving the low temperature toughness with increasing wall thickness of the pipeline is very difficult. To overcome the difficulty of producing consistent low temperature toughness in heavy wall pipe Shougang Steel Research in cooperation with the Shougang Steel Qinhuangdao China (Shouqin) 4.3 m heavy wide plate mill research was conducted. This paper describes the background, composition design and process strategy to produce good low temperature toughness in heavy wall API plate. The importance of the slab reheating schedule and recrystallized rolling process/schedule that occurs during the roughing process will be discussed. The effect of per pass reductions and work roll speed rotation on the strain introduced was analyzed by means of the numerical simulation technology. Furthermore, the center thickness microstructure and low temperature toughness of plate under the different rolling schedules were researched. The results showed a low reheating temperature and slow rough rolling speed should be implemented. The per pass reductions during recrystallized rough rolling should be increased in a steady fashion, with special emphasis on the reduction of the final roughing pass prior to the intermediate hold (transfer thickness for finishing). When the final roughing pass had a per pass reduction of more than 15%, the main microstructure of plate consists of uniform (surface to center) fine ferrite/acicular ferrite with a small volume fraction of M-A constituent. This fine uniform microstructure results in good low temperature fracture toughness in heavier plate thicknesses. Results of this research and development work will be discussed.

Development of X80M Line Pipe Steel for Spiral Welded Pipes With Low Temperature Toughness and Excellent Weldability

2014 ◽  
Author(s):  
Nuria Sanchez ◽  
Özlem E. Güngör ◽  
Martin Liebeherr ◽  
Nenad Ilić
Keyword(s):  
Low Temperature ◽  
Life Cycle Cost ◽  
Volume Fraction ◽  
Large Diameter ◽  
Pipe Production ◽  
Strain Accumulation ◽  
Long Distance ◽  
Line Pipe ◽  
Low Temperature Toughness ◽  
Welded Pipe

The unique combination of high strength and low temperature toughness on heavy wall thickness coils allows higher operating pressures in large diameter spiral welded pipes and could represent a 10% reduction in life cycle cost on long distance gas pipe lines. One of the current processing routes for these high thickness grades is the thermo-mechanical controlled processing (TMCP) route, which critically depends on the austenite conditioning during hot forming at specific temperature in relation to the aimed metallurgical mechanisms (recrystallization, strain accumulation, phase transformation). Detailed mechanical and microstructural characterization on selected coils and pipes corresponding to the X80M grade in 24 mm thickness reveals that effective grain size and distribution together with the through thickness gradient are key parameters to control in order to ensure the adequate toughness of the material. Studies on the softening behavior revealed that the grain coarsening in the mid-thickness is related to a decrease of strain accumulation during hot rolling. It was also observed a toughness detrimental effect with the increment of the volume fraction of M/A (martensite/retained austenite) in the middle thickness of the coils, related to the cooling practice. Finally, submerged arc weldability for spiral welded pipe manufacturing was evaluated on coil skelp in 24 mm thickness. The investigations revealed the suitability of the material for spiral welded pipe production, preserving the tensile properties and maintaining acceptable toughness values in the heat-affected zone. The present study revealed that the adequate chemical alloying selection and processing control provide enhanced low temperature toughness on pipes with excellent weldability formed from hot rolled coils X80 grade in 24 mm thickness produced at ArcelorMittal Bremen.

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.

The Analysis of Low Temperature Toughness on X80 Pipeline Steel Welded Joint

2018 ◽  
Vol 71 (10) ◽  
pp. 2517-2526 ◽  
Author(s):  
Bin Wang ◽  
Yingchao Xu ◽  
Jing Hu ◽  
Senfeng Zhang ◽  
Chengwu Cui ◽  
...  
Keyword(s):  
Low Temperature ◽  
Welded Joint ◽  
Pipeline Steel ◽  
X80 Pipeline Steel ◽  
Low Temperature Toughness

Effect of Ferrite Volume Fraction on Mechanical Properties of X80 Pipeline Steel

2014 ◽  
Vol 989-994 ◽  
pp. 212-215
Author(s):  
J. Liu ◽  
G. Zhu ◽  
W. Mao
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Work Hardening ◽  
Single Phase ◽  
Volume Fraction ◽  
Pipeline Steel ◽  
X80 Pipeline Steel ◽  
Hardening Behavior ◽  
Two Phases ◽  
Better Than

The effect of volume fraction of ferrite on the mechanical properties including strength, plasticity and wok hardening was systematically investigated in X80 pipeline steel in order to improve the plasticity. The microstructures with different volume fraction of ferrite and bainite were obtained by heat-treatment processing and the mechanical properties were tested. The work hardening behavior was analyzed by C-J method. The results show that the small amount of ferrite could effectively improve the plasticity. The work hardening ability and the ratio of yield/tensile strength with two phases of ferrite/bainite would be obviously better than that with single phase of bainite. The improvement of plasticity could be attributed to the ferrite in which more plastic deformation was afforded.

Experimental Study of Fatigue Crack Overload Retardation in X80 Grade Steel

2008 ◽  
Author(s):  
Qingquan Duan ◽  
Hong Zhang ◽  
Feng Yan
Keyword(s):  
Fatigue Crack ◽  
Crack Growth ◽  
Oil And Gas ◽  
Prediction Models ◽  
Pipeline Steel ◽  
Compact Tension ◽  
X80 Pipeline Steel ◽  
Oil And Gas Pipelines ◽  
Crack Retardation ◽  
Grade Steel

The tests of fatigue crack overload retardation were performed to gain a some what deeper understanding of overload retardation. We present an experimental investigation of fatigue crack retardation behavior caused by intermediate single peak tensile overload under constant amplitude cyclic loading. The compact tension (CT) specimens of API grade X80 pipeline steel were used in fatigue test. The results show there was an instant crack extension during overloading for the tested overload ratios. As soon as the overload cycle was removed, instant delay in crack growth occurred. The results should be of interest for fracture mechanics prediction models on fatigue crack growth under variable amplitude loading and overloading effect for oil and gas pipelines.

scholarly journals Experimental Research on Fatigue Properties of X80 Pipeline Steel for Synthetic Natural Gas Transmission

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Li Yan–hua ◽  
Feng Hui ◽  
Chi Qiang ◽  
Fei Fan ◽  
Gao Xiong-xiong ◽  
...  
Keyword(s):  
Natural Gas ◽  
Base Metal ◽  
Hydrogen Content ◽  
Volume Fraction ◽  
Pipeline Steel ◽  
Fatigue Properties ◽  
High Grade ◽  
Long Distance ◽  
X80 Pipeline Steel ◽  
Synthetic Natural Gas

In recent years, many synthetic natural gas demonstration projects have been put into operation all over the world, and hydrogen is usually contained in synthetic natural gas. X80 is the most commonly used high-grade pipeline steel in the construction of natural gas pipelines. The compatibility between high-grade pipeline steel and hydrogen directly affects safety and reliability of long-distance pipelines. Therefore, in order to study the effect of hydrogen content on fatigue properties of high-grade pipeline steel, fatigue specimens were taken from base metal, spiral welds, and girth weld of submerged arc spiral welded pipes, respectively. Specifically, the total pressure was 12 MPa and hydrogen content was from 0 to 5vol%. Experimental results indicate that the hydrogen significantly increases the fatigue crack growth rate for both base metal, spiral weld, and heat-affected zone of X80 pipeline steel for about ten times compared with reference environment nitrogen, hydrogen would greatly reduce the fatigue life of the X80 pipeline steel, and the fatigue lifetime would decrease with the increase in hydrogen volume fraction. In order to ensure the safe operation of SNG pipeline, the hydrogen content should be controlled as low as possible.

Fracture and Crack Propagation Behavior of 560 MPa Microalloyed Pipeline Steel under Different Cooling Schedules

2017 ◽  
Vol 898 ◽  
pp. 1094-1102 ◽  
Author(s):  
Jin Hua Zhao ◽  
Dong Fang Li ◽  
Guo Yuan ◽  
Xue Qiang Wang ◽  
Rui Hao Li ◽  
...  
Keyword(s):  
Grain Size ◽  
Low Temperature ◽  
Crack Propagation ◽  
Pipeline Steel ◽  
Crack Arrest ◽  
Dominant Factor ◽  
Cooling Schedules ◽  
Effective Grain Size ◽  
Mixed Microstructure ◽  
Low Temperature Toughness

Three kinds of pipeline steel with different microstructures were fabricated by varying cooling schedules during thermo-mechanical controlled processing (TMCP). Charpy impact property of the pipeline steels were obtained, and the fracture and crack-arrest mechanisms were further studied. The results indicated that the steels were classified into two kinds according to their microstructures, the mixture of acicular ferrite (AF), quasi-polygonal ferrite (QF), granular bainite (GB) and small fraction of degenerate pearlite (DP), and the mixed microstructure of AF and GB, respectively. The processed steel with microstructure of AF and GB exhibited more excellent low-temperature toughness and crack-arrest properties with upper shelf energy of ~281 J and energy transition temperature of ~-76°C. The mixed microstructure (AF + GB) possessing smaller effective grain size hindered the propagating of crack and consumed large amount of energy during fracture. The effective grain size of microstructure was the dominant factor controlling low-temperature toughness and crack-arrest properties of pipeline steel, which increased the high-angle boundary length per unit area and further increased the crack propagation energy during fracture.

Research and Development of Deep-Sea Pipeline Steel

2010 ◽  
Vol 152-153 ◽  
pp. 1492-1498
Author(s):  
Jin Qiao Xu ◽  
Bin Guo ◽  
Lin Zheng ◽  
Yin Hua Li ◽  
Le Yu
Keyword(s):  
Low Temperature ◽  
Deep Sea ◽  
Pipeline Steel ◽  
High Strength ◽  
Steel Company ◽  
Line Pipe ◽  
Iron And Steel ◽  
Company Group ◽  
Pipeline Project ◽  
Low Temperature Toughness

This paper provides a detailed description of deep-sea pipeline steel developed at Wuhan Iron and Steel Company(Group), WISCO for short. The thickness of the trial produced plates is 28mm. The chemical composition of low C-high Mn-Nb-Ti with proper content of other alloys and thermo-mechanical controlled process were applied. The results show that the deep-sea pipeline steel developed at Wuhan Iron and Steel Company has a good match of high strength, low temperature toughness and excellent deformability with fine uniform microstructure. The LSAW line pipe manufactured by JCOE method has high strength, good low temperature toughness and low yield ratio which comprehensively meet the requirements of the South China Sea Liwan pipeline project.

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