scholarly journals Research on Acicular Ferrite Nucleation Induced by Inclusions in Pipeline Steel Welding Heat Affected Zone

2015 ◽  
Author(s):  
Jian-Ming Wang ◽  
Yan Liu ◽  
Kai Wang ◽  
Yang Liu
Keyword(s):  
Heat Affected Zone ◽  
Acicular Ferrite ◽  
Pipeline Steel ◽  
Ferrite Nucleation

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

Nucleation of Intragranular Acicular Ferrite in the Heat Affected Zone of Ti-Bearing Hsla Steel

2010 ◽  
Vol 168-170 ◽  
pp. 837-841
Author(s):  
Li Qing Zhang ◽  
Kai Ming Wu
Keyword(s):  
Heat Affected Zone ◽  
Acicular Ferrite ◽  
Hsla Steel ◽  
High Strength ◽  
Complex Oxides ◽  
Low Alloy Steel ◽  
X Ray ◽  
Nucleation Sites ◽  
Intragranular Acicular Ferrite ◽  
Ferrite Nucleation

The nucleation of intragranular acicular ferrite in the welding heat-affected zone of Ti-bearing high strength low alloy steel was investigated by means of electron microscopy. It was found that intragranular acicular ferrite nucleation sites under different welding heat inputs (4.3kJ/mm and 10.0kJ/mm) are titanium complex oxides on which manganese (Mn) sulfides are precipitated. The complex compound is a Si and Mn-enriched oxide. Analysis of the oxide by means of enenrgy dispersive X-ray spectrum indicated that the oxide has higher absorption ability of Si than that of Mn.

scholarly journals The Microstructure and Property of the Heat Affected zone in C-Mn Steel Treated by Rare Earth

2019 ◽  
Vol 38 (2019) ◽  
pp. 362-369 ◽  
Author(s):  
Ming-ming Song ◽  
Yu-min Xie ◽  
Bo Song ◽  
Zheng-liang Xue ◽  
Nan Nie ◽  
...  
Keyword(s):  
Rare Earth ◽  
Impact Toughness ◽  
Heat Affected Zone ◽  
Acicular Ferrite ◽  
Steel Matrix ◽  
Impact Properties ◽  
Treated Steel ◽  
The Impact ◽  
Welding Processes ◽  
Mn Steel

AbstractThe microstructures and impact properties of the heat affected zone (HAZ) in steel treated by rare earth (RE) under different welding processes were discussed. The effect of Al on the impact properties of the HAZ in RE treated steel was analyzed. It finds that when the welding t8/5 is smaller than 111 s, the main microstructure in steels is bainite/widmanstatten. The impact toughness of the HAZ is lower than that of the steel matrix. When t8/5 is more than 250 s, the microstructure is mainly acicular ferrite (AF) in the steel treated by RE, and the impact toughness of HAZ is obviously improved. Even under the welding processing with t8/5 about 600 s in RE treated steel can still obtain a lot of AF. While in the steel killed by Al and treated by RE, the main microstructure is parallel cluster of bainite/widmanstatten, and the impact toughness of HAZ is significantly lower than that of low-Al RE treated steel. Al can deteriorate the optimizing of RE treatment on HAZ.

scholarly journals Microstructure and Corrosion Resistance to H2S in the Welded Joints of X80 Pipeline Steel

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1325 ◽  
Author(s):  
Jian-Bao Wang ◽  
Guang-Chun Xiao ◽  
Wei Zhao ◽  
Bing-Rong Zhang ◽  
Wei-Feng Rao
Keyword(s):  
Corrosion Resistance ◽  
Heat Affected Zone ◽  
Welded Joints ◽  
Electrochemical Impedance ◽  
Pipeline Steel ◽  
Electrochemical Corrosion ◽  
Open Circuit ◽  
Coarse Grained ◽  
Granular Bainite ◽  
X80 Pipeline Steel

The microstructure and corrosion resistance in H2S environments for various zones of X80 pipeline steel submerged arc welded joints were studied. The main microstructures in the base metal (BM), welded metal (WM), coarse-grained heat-affected zone (CGHAZ), and fine-grained heat-affected zone (FGHAZ) were mainly polygonal ferrite and granular bainite; acicular ferrite with fine grains; granular bainite, ferrite, and martensite/austenite constituents, respectively. The corrosion behavior differences resulted from the microstructure gradients. The results of the micro-morphologies of the corrosion product films and the electrochemical corrosion characteristics in H2S environments, including open circuit potential and electrochemical impedance spectroscopy, showed that the order of corrosion resistance was FGHAZ > BM > WM > CGHAZ.

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.

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