Effect of Cooling Process on Microstructure Especially Precipitation Behavior of High-Strength Pipeline Steel

2020 ◽  
Author(s):  
Zheng Hesong ◽  
Niu Tao ◽  
Li Fei
Keyword(s):  
Pipeline Steel ◽  
Nano Particles ◽  
Precipitation Process ◽  
High Grade ◽  
Laminar Cooling ◽  
Precipitation Behavior ◽  
Cooling Process ◽  
Controlled Cooling ◽  
Two Stage ◽  
High Deformability

Abstract The effect of different cooling processes on microstructure especially precipitation behavior and properties of high grade pipeline steel was investigated in this paper. The results showed that: By two stage controlled cooling process, ferrite-bainite phase was obtained in X80 pipeline steel with high deformability, the average size of Martensite and Austenitic islands (M/A) was approximately 1μm, the Uniform Elongation (UEl) was 10%. Whereas granular bainite was obtained after conventional laminar cooling process and fine M/A of 1∼2μm size dispersed in grains or along grain boundaries. Compared with conventional pipeline steel, high deformability pipeline steel through two stage controlled cooling process had higher Elongation (El), impact toughness and lower yield ratio, due to the existence of ferrie+bainite phase structure which reduced yield strength (YS) and enhanced deformation performance and fracture toughness. Additionally, the effect of precipitation strengthening of high grade pipeline steel produced by Ultra-fast cooling (UFC) process was superior to that produced by conventional laminar cooling process. A significant amount of nano particles precipitated with the size of 1nm to 5nm were obtained through the UFC process. The application of UFC made the precipitation process avoid the nose temperature of precipitation temperature time (PTT) curve, thus the size of nano particles were smaller and the distribution of precipitation was more dispersive.

Microstructure and Mechanical Properties of X80/X100 High Deformability Pipeline Steel

2011 ◽  
Vol 399-401 ◽  
pp. 139-143
Author(s):  
Dian Xiu Xia ◽  
De Liang Meng ◽  
Shou Yong An ◽  
Yong Lin Kang
Keyword(s):  
Pipeline Steel ◽  
Large Strain ◽  
High Strength ◽  
Longitudinal Direction ◽  
Granular Bainite ◽  
Dual Phase ◽  
Cooling Process ◽  
Bainite Structure ◽  
Lath Bainite ◽  
High Deformability

In the present study, X80 and X100 grade high deformability pipeline steels have been processed by using TMCP and followed two-stage cooling process. The microstructures of the X80HD (HD, high deformability) and X100HD steels were both characterized by ferrite-bainite dual phase. The grains sizes of ferrite were mostly less than 5μm and the volume fractions were about 20~25% in X80HD and 10~15% in X100HD steel. The bainite structure in X80HD steel was granular bainite (GB); while in X100HD steel large amounts of lath bainite (LB) were also formed besides GB, and bainite grains were much finer. Ferrite-bainite dual phase microstructure has large strain hardenability that resulting high strength and high deformability combination. Both the steels exhibit high strength/toughness in transverse direction and high deformability in longitudinal direction. The X100HD steel with more volume of LB and less volume of PF has higher strength but lower deformability than that of X80HD steel.

Intelligent Setting Method of Laminar Cooling Process for Hot Rolled Strip

2013 ◽  
Vol 756-759 ◽  
pp. 4377-4381
Author(s):  
Jing Hou ◽  
Jin Xiang Pian ◽  
Yan Ling Sun ◽  
Ke Xu
Keyword(s):  
Working Condition ◽  
Cooling Water ◽  
Water Volume ◽  
Rolled Strip ◽  
Model Parameters ◽  
Case Based Reasoning ◽  
Laminar Cooling ◽  
Cooling Process ◽  
Coiling Temperature ◽  
Operation Condition

In order to improve the control accuracy of the coiling temperature of strip in the laminar cooling process when working condition is varying, an intelligent setting method of the cooling water volume is researched in this paper. The strip coiling temperature mechanism model is built firstly. Secondly, the key model parameters are identified with case-based reasoning (CBR) technology to improve the model accuracy. Lastly, the cooling water volume setting method based the model is proposed where disturbance input method is applied. The simulation result showed that the proposed method can improve the strip coiling temperature accuracy when the operation condition is changing. The strip coiling temperature accuracy can be improved due to the CBR technology which can adjust the key model parameters according to the varying operation condition. So, the setting values based the improved model are adjusted with the changing working condition, with self-adaptive ability.

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.

scholarly journals Two-stage particle separation channel based on standing wave surface acoustic wave

2021 ◽  
Author(s):  
Xueye Chen ◽  
Yaolong Zhang
Keyword(s):  
Sound Pressure ◽  
High Efficiency ◽  
Microfluidic Channel ◽  
Particle Separation ◽  
Disease Diagnosis ◽  
Nano Particles ◽  
Two Stage ◽  
Separation Channel ◽  
Practical Applications ◽  
Electrode Voltage

Abstract Microfluidic technology has great advantages in the precise manipulation of micro and nano particles, and the collection method of micro and nano particles based on ultrasonic standing waves has attracted much attention for its high efficiency and simplicity of structure. This paper proposes a two-stage particle separation channel using ultrasound. In the microfluidic channel, two different sound pressure regions are used to achieve the separation of particles with positive acoustic contrast factors. Through numerical simulation, the performance of three common piezoelectric substrate materials was compared qualitatively and quantitatively, and it was found that the output sound pressure intensity of 128°YX-LiNbO3 was high and the output was stable. At the same time, the influence of the number of electrode pairs of the interdigital transducer and the electrode voltage on the output sound wave is studied. Finally, 15 pairs of electrode pairs are selected, and the electrode voltages of the two sound pressure regions are 2.0V and 3.0V respectively. After selecting the corresponding parameters, the separation process was numerically simulated, and the separation of three kinds of particles was successfully achieved. This work has laid a certain theoretical foundation for rapid disease diagnosis and real-time monitoring of the environment in practical applications.

FE Analysis of Hot Strips’ Temperature Distribution in Laminar Cooling Process

2014 ◽  
Vol 900 ◽  
pp. 647-650
Author(s):  
Yu Qing Zheng ◽  
Jing Yu Cui
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Rolled Strip ◽  
Fe Model ◽  
Laminar Cooling ◽  
Cooling Process ◽  
Transfer Coefficients ◽  
Position Effects ◽  
Simulation Accuracy ◽  
Hot Rolled

The temperature distribution of the hot-rolled strip in the ROT cooling process was calculated and analyzed using ABAQUS in this paper. The complicated heat transfer coefficients of hot strip considering the position effects of top and bottom nozzles, and the non-uniform heat transfer situation along the width direction were defined by user subroutine. The simulation results were in good correlation with test results. It’s helpful for further analysis to improve the temperature distribution uniformity and the simulation accuracy for FE model, and guide the on-site production.

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