scholarly journals Precipitates in Nb and Nb–V Microalloyed X80 Pipeline Steel

2013 ◽  
Vol 19 (S5) ◽  
pp. 62-65 ◽  
Author(s):  
Zhongyi Li ◽  
Delu Liu ◽  
Jianping Zhang ◽  
Wenhuai Tian
Keyword(s):  
Hot Rolling ◽  
Microalloyed Steel ◽  
Pipeline Steel ◽  
Titanium Nitrides ◽  
Vanadium Compounds ◽  
X80 Pipeline Steel ◽  
Energy Filtering ◽  
Transmission Electron ◽  
The Matrix ◽  
X80 Steel

AbstractPrecipitates in two X80 pipeline steels were studied by transmission electron microscopy equipped with an energy filtering system. The steels are microalloyed with niobium and niobium–vanadium (Nb–V), respectively, and produced by continuous hot rolling. Besides the precipitates TiN and (Ti, Nb) (C, N), which were 10–100 nm in size, a large number of precipitates smaller than 10 nm distributed in the two steels have been observed. In the Nb–V microalloyed steel, only a few titanium nitrides covered by vanadium compounds on the surface have been observed. It is inferred that the vanadium exists mainly in the matrix as a solid solution element. The fact has been accepted that there was no contribution to the precipitation strengthening of the X80 steel by adding 0.04–0.06% vanadium under the present production process. By contrast, the toughness of the Nb–V steel is deteriorated. Therefore, a better toughness property of the Nb microalloyed X80 results from the optimum microalloying composition design and the suitable accelerating cooling after hot rolling.

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.

SEM In Situ Investigation on Fatigue Cracking Behavior of X80 Pipeline Steel with Inclusions

2011 ◽  
Vol 284-286 ◽  
pp. 1096-1100 ◽  
Author(s):  
Ke Tong ◽  
Yan Ping Zeng ◽  
Xin Li Han ◽  
Yao Rong Feng ◽  
Xiao Dong He
Keyword(s):  
Crack Initiation ◽  
Pipeline Steel ◽  
Fatigue Cracking ◽  
Fatigue Loading ◽  
In Situ Observation ◽  
X80 Pipeline Steel ◽  
Cracking Behavior ◽  
The Matrix ◽  
Extension Period

The micro-mechanical behavior of inclusions in X80 pipeline steel under fatigue loading was investigated by means of SEM in situ observation. The influence of sizes and shapes of inclusion on crack initiation and propagation was analyzed. The result shows that for large-size single-particle inclusion, cracks initiate from the interior under the fatigue loading. When a certain circulation cycles are reached, cracks initiate at the matrix near the sharp corner of the inclusion. The cracks extend at the matrix during the stable extension period and unstable extension period following the crack initiation, until fracture occurred. For chain inclusion, cracks first initiate at the interface between inclusion and matrix within the chain area, and the circulation cycles needed for initiation are far less than single inclusion. Cracks steadily extend after the initiation, and then fracture after very short circulation cycles. A chain of inclusion with the shape corners is serious harmful to the fatigue properties.

Quenching Temperature‘s Impact on the Microstructure and Mechanical Properties of X80 Pipeline Steel

2011 ◽  
Vol 308-310 ◽  
pp. 762-766
Author(s):  
Yong Jie Ma ◽  
Xi Lu Liu ◽  
Guang Liang Zhang
Keyword(s):  
Mechanical Properties ◽  
Pipeline Steel ◽  
X80 Pipeline Steel ◽  
Quenching Temperature ◽  
Austenite Grain ◽  
State Study ◽  
Lath Bainite ◽  
Small Needle ◽  
X80 Steel ◽  
Increased Strength

The state study on mechanical properties’ changes of X80 steel at different quenching temperature. The results showed that the quenching temperature is 1000 °C, X80 Austenite grain coarsening is serious, leading to the production of coarse lath bainite ferrite, resulting in increased strength of X80 steel, toughness and hardness of a serious reduction; When the quenching temperature is 930 °C, and assisted by the appropriate temperatures, can make the X80 steel the small needle-like ferrite-based organizations, to obtain good hardness, strength, ductility and toughness of the match.

scholarly journals Electrochemical Investigation of Corrosion of X80 Steel under Elastic and Plastic Tensile Stress in CO2 Environment

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 949 ◽  
Author(s):  
Wei Wu ◽  
Hailong Yin ◽  
Hao Zhang ◽  
Jia Kang ◽  
Yun Li ◽  
...  
Keyword(s):  
Corrosion Rate ◽  
Tensile Stress ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Pipeline Steel ◽  
Open Circuit ◽  
Co2 Corrosion ◽  
X80 Pipeline Steel ◽  
X80 Steel ◽  
Co2 Environment

An investigation into the electrochemical corrosion behavior of X80 pipeline steel under different elastic and plastic tensile stress in a CO2-saturated NaCl solution has been carried out by using open-circuit potential, potentiodynamic polarization, electrochemical impedance spectroscopy, and surface analysis techniques. The results show that the corrosion rate of X80 steel first increases and then slightly decreases with the increase of elastic tensile stress, whereas the corrosion rate sharply increases with the increase of plastic tensile stress. Both elastic and plastic tensile stress can enhance steel corrosion by improving the electrochemical activity of both anodic and cathodic reactions. Moreover, compared with elastic tensile stress, plastic tensile stress has a more significant effect. Furthermore, electrochemical reactions for CO2 corrosion and mechanoelectrochemical effect are used to reasonably explain the corrosion behavior of stressed X80 steel in CO2 environment.

Effects of Hydrogen on Electrochemical Behaviors of X80 Steel in Simulated Soil Solution

2011 ◽  
Vol 335-336 ◽  
pp. 468-473 ◽  
Author(s):  
Chuan He ◽  
Xu Chen ◽  
Yang Xu ◽  
Zhi Yong Liu
Keyword(s):  
Soil Solution ◽  
Current Density ◽  
Polarization Resistance ◽  
Pipeline Steel ◽  
Charge Transfer Resistance ◽  
X80 Pipeline Steel ◽  
Transfer Resistance ◽  
Hydrogen Charging ◽  
Charging Time ◽  
X80 Steel

X80 pipeline steel specimens were treated by electrochemical hydrogen charging under various current density and charging time. The polarization resistance and corrosion rate of X80 steel were analyzed in Yingtan simulated soil solution under the different hydrogen charging conditions. The results showed that hydrogen accelerated anodic dissolution and enhanced corrosion sensitivity. With hydrogen in the steel, the charge transfer resistance and polarization resistance decreased, double electric layer capacitor and corrosion current increased. The effects were enhanced with the increase of hydrogen charging time and current density.

Effect of Applied Potentials on Stress Corrosion Cracking Susceptibility of X80 Pipeline Steel in Simulated Soil Solution

2010 ◽  
Vol 146-147 ◽  
pp. 920-925 ◽  
Author(s):  
Yuan Cheng ◽  
Hong Ying Yu ◽  
Li Xin Zhang ◽  
Ying Wang ◽  
Xu Meng ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Stress Corrosion ◽  
Soil Solution ◽  
Stress Corrosion Cracking ◽  
Pipeline Steel ◽  
Corrosion Cracking ◽  
X80 Pipeline Steel ◽  
X80 Steel ◽  
Scanning Electron

The stress corrosion cracking susceptibility of X80 pipeline steel was investigated in a simulated soil solution using slow strain rate tensile (SSRT) tests. The different potentials were applied in the tests. The fracture surfaces were observed using scanning electron microscopy (SEM). The X80 steel was susceptible to SCC in simulated solution. The SCC susceptibility had no apparent change with the anodic potentials applied. The fracture mechanism was anodic dissolution. However, the SCC susceptibility increased with the decrease of the cathodic potentials obviously. The cracking was induced by the Hydrogen diffusing into the metal.

Effect of Potentials on Stress Corrosion Cracking of X80 Pipeline Steel in Simulated Soil Solution

2011 ◽  
Vol 197-198 ◽  
pp. 1549-1554 ◽  
Author(s):  
Yuan Cheng ◽  
Hong Ying Yu ◽  
Ying Wang ◽  
Xu Meng ◽  
Li Xin Zhang ◽  
...  
Keyword(s):  
Strain Rate ◽  
Stress Corrosion ◽  
Soil Solution ◽  
Anodic Dissolution ◽  
Stress Corrosion Cracking ◽  
Fracture Mechanism ◽  
Pipeline Steel ◽  
Corrosion Cracking ◽  
X80 Pipeline Steel ◽  
X80 Steel

The stress corrosion cracking (SCC) susceptibility of X80 pipeline steel, which was used in the Second West-East Gas Pipeline, was investigated in simulated soil solution of Xinzhou in Hubei province of China. The SCC susceptibility was studied using the slow strain rate tensile (SSRT) tests in which different potentials were applied. The fracture surfaces were observed using SEM. X80 steel was susceptible to SCC in simulated solution. The SCC was not serious with the anodic potentials applied. The fracture mechanism was anodic dissolution. But the SCC was affected obviously with different cathodic potentials because of the different influence of the hydrogen.

Quantitative Energy-filtering Transmission Electron Microscopy in Materials Science

2000 ◽  
Vol 6 (2) ◽  
pp. 161-172 ◽  
Author(s):  
Werner Grogger ◽  
Ferdinand Hofer ◽  
Peter Warbichler ◽  
Gerald Kothleitner
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Materials Science ◽  
Steel Specimen ◽  
Elemental Distribution ◽  
Secondary Phases ◽  
Energy Filtering ◽  
Transmission Electron ◽  
The Matrix ◽  
Titanate Ceramics

Energy-filtered transmission electron microscopy (EFTEM) can be used to acquire elemental distribution images at high lateral resolution within short acquisition times. In this article, we present an overview of typical problems from materials science which can be preferentially solved by means of EFTEM. In the first example, we show how secondary phases in a steel specimen can be easily detected by recording jump ratio images of the matrix element under rocking beam illumination. Secondly, we describe how elemental maps can be converted into concentration maps. A Ba-Nd-titanate ceramics serves as a typical materials science example exhibiting three different compounds with varying composition.

Frequency Domain Analysis and Application of Electrochemical Noise of X80 Pipeline Steel

2014 ◽  
Vol 1015 ◽  
pp. 659-662
Author(s):  
Peng Xin Feng ◽  
Wen Long Xu ◽  
Hai Tao Lai ◽  
Xun Zhu ◽  
Wen Wei Lu ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Electrochemical Noise ◽  
Pipeline Steel ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Metal Corrosion ◽  
Linear Segment ◽  
X80 Pipeline Steel ◽  
X80 Steel ◽  
Moisture Potential

In this paper, frequency domain analysis and application of electrochemical noise of X80 Pipeline Steel in Xinzhou Soil is researched. In the frequency data analysis of electrochemical noise, there are three characteristic parameters. It can be seen from experiments that X80 steel buried in Xinzhou soil with14% moisture content shows that metal corrosion is still not change much. And, it can be inferred that corrosion of X80 pipeline steel in Xinzhou soil with 18% moisture, corrosion is uniform while the morphology is not the uniform , it is the morphology that some pitting are connecting into the film. In Xinzhou soil with 22% moisture, potential PSD figure is different after corrosion happened for one day and three days. Thus, the corrosion type can be determined by high-frequency slope of the linear segment of potential PSD figure.

Fractal characteristics of AC corrosion morphology of X80 pipeline steel in coastal soil solution

2019 ◽  
Vol 66 (6) ◽  
pp. 868-878
Author(s):  
Yu Fu ◽  
Jie Kou ◽  
Cuiwei Du
Keyword(s):  
Fractal Dimension ◽  
Soil Solution ◽  
Corrosion Behavior ◽  
Pipeline Steel ◽  
Three Dimensional ◽  
Uniform Corrosion ◽  
X80 Pipeline Steel ◽  
Corrosion Morphology ◽  
Content Type ◽  
X80 Steel

Purpose Pipelines are seriously corroded due to the close distance between pipelines and high voltage transmission lines. The purpose of this paper is to study the influence of alternating current (AC) on corrosion behavior of X80 pipeline steel in coastal soil solution. Design/methodology/approach The corrosion behavior of X80 steel under different AC densities in coastal soil solution was investigated by electrochemical measurements and image processing technology. Furthermore, a quantitative description model of AC corrosion through fractal dimension of corrosion image was established. Findings The results show that under low AC density the X80 steel is mainly uniform corrosion, and once AC density reaches 150 A/m2, the corrosion morphology gradually turns to pitting corrosion with irregular circle. For another aspect, the fractal dimension of corrosion images shows that the two/three-dimensional fractal dimension increase with the increase of AC density, presenting a linear and an exponential relationship respectively. In addition, the variation of the three-dimensional fractal dimension is the same as that of average corrosion rate. The threshold of the increasing trend of fractal dimension as well as corrosion type is 150 A/m2. Originality/value The investigation provides a quantitative method to describe AC corrosion morphology through fractal dimension. Furthermore, the method is of benefit to process corrosion images automatically.

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