Effects of M/A Islands Microstructure Characteristic on Mechanic Properties of High Grade Pipeline Steel

2010 ◽  
Author(s):  
Ke Tong ◽  
Xiaodong Shao ◽  
Lixia Zhu ◽  
Qiang Liu ◽  
Jinfeng Li
Keyword(s):  
Volume Fraction ◽  
Pipeline Steel ◽  
Yield Ratio ◽  
Material Strength ◽  
High Grade ◽  
Microstructure Characteristics ◽  
Average Dimension ◽  
Microstructure Characteristic

The microstructure characteristic of martensite/austenite (M/A) islands of X80-1#, X80-2#, X100-3#, X100-4# steel pipelines come from different manufacturer were investigated by OM and SEM contrastively, and the influence of M/A islands microstructure characteristics of pipelines were studied combining with tests of mechanic properties. The result shows that the effect of the M/A islands volume fraction, average dimension, form and distribution on the material strength, yield ratio and toughness were distinct. When the M/A islands distribute uniformly with small size and spherical or crossed strip form, under the certain volume fraction, the pipeline steel exhibits excellent strength-toughness matching.

Research and Prospect on Relationship Between Microstructure Characteristics and Strength-Toughness of High Grade Pipeline Steel

2010 ◽  
Author(s):  
Ke Tong ◽  
Chuanjing Zhuang ◽  
Xiaodong He ◽  
Xinli Han ◽  
Juan Song
Keyword(s):  
Grain Size ◽  
Oil And Gas ◽  
Pipeline Steel ◽  
Rapid Development ◽  
In Situ Observation ◽  
High Grade ◽  
Banded Structure ◽  
Microstructure Characteristics ◽  
Effective Grain Size ◽  
Microstructure Characteristic

The strength property of high grade pipeline steel has been obviously improved with the rapid development of the constructing of oil and gas pipelines. And the excellent strength-toughness matching of pipeline steel is very important. The major affecting factor on strength-toughness of pipeline steel is microstructure characteristic. In this paper, the research status of pipeline steel microstructure characteristic including effective grain size, non-metallic inclusions and banded structure is summarized at home and abroad. In addition, the shortcomings of former research on the relationship between microstructure characteristics and strength-toughness are also analyzed for this pipeline steel. On this basis, a solution is put forward to investigate the characterization of effective grain size and micro-mechanical behavior of inclusions and banded structure with the method of electron backscatter diffraction and the method of SEM in situ observation. And the necessities and feasibilities of the solution are discussed.

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.

Effects of Finish Cooling Temperature on Microstructure and Properties of X100 Pipeline Steels

2016 ◽  
Vol 850 ◽  
pp. 993-999
Author(s):  
Shu Jun Jia ◽  
Qing You Liu ◽  
Ba Li ◽  
Hong Mei Hao
Keyword(s):  
Volume Fraction ◽  
Pipeline Steel ◽  
Steel Production ◽  
Mechanical Tests ◽  
Yield Ratio ◽  
Pipeline Steels ◽  
Cooling Temperature ◽  
Key Factor ◽  
X100 Pipeline Steel ◽  
Peak Value

The effect of finish cooling temperature on microstructure and mechanical properties of X100 pipeline steels were investigated through SEM, TEM and mechanical tests. The results showed that the effect of finish cooling temperature on tensile strength of studied steels were slight in the temperature range of 180°C~500°C. The yield ratio, yield strength and impact toughness all presented peak value when the finish cooling temperature was 360°C, however, both the volume fraction and particle size of MA component at 360°C finish cooling temperature had the minimum values. As a brittle hardening phase in bainite the increased number and enlarged size of the MA component were the key factor of the decrease of the yield ratio and toughness. Therefore, rational choosing finish cooling temperature could optimize the morphology and distribution of MA component to make sure the required strength and toughness for the X100 pipeline steel production.

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.

Influence of Volume Fraction of Bainite on Mechanical Properties of X80 Pipeline Steel with Excellent Deformability

2011 ◽  
Vol 695 ◽  
pp. 271-274
Author(s):  
Xiao Yong Zhang ◽  
Hui Lin Gao ◽  
Xue Qin Zhang ◽  
Yan Yang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Yield Strength ◽  
Volume Fraction ◽  
Pipeline Steel ◽  
Dual Phase ◽  
Absorption Energy ◽  
Impact Absorption Energy ◽  
Impact Absorption ◽  
Work Hardening Exponent

The pipeline steel with excellent deformability with ferrite and bainite dual-phase microstructure are obtained by inter-critically accelerating cooling method, aiming to get good deformation capability of avoiding failure from the geological disasters such as landslides and earthquake. The influence of volume fraction of bainite on the mechanical properties of dual-phase pipeline steels was investigated by means of microscopic analysis method and mechanical properties testing. The results indicated that both yield strength and ultimate tensile strength of the steels increase almost linearly with the increasing volume fraction of bainite, while ductility, work hardening exponent and impact absorption energy decrease. When the volume fraction of bainite is about 50%, the yield strength, the yield strength/tensile strength ratio (Y/T), work hardening exponent, uniform elongation and impact absorption energy of X80 pipeline steels with excellent deformability is 665MPa, 0.8, 0.12, 8% and 245J respectively.

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