Comparative study of microstructure and toughness of automatic welded joints of X70 pipeline steel with no slope and 25° slope

Li, Liying; Fu, Jinqiu; Wang, Xuejun; Liu, Kai; Niu, Xianwei; Niu, Shengyuan; Li, Xueda; Han, Bin

doi:10.1016/j.ijpvp.2023.105054

Cited by 8 publications

(1 citation statement)

References 20 publications

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“…Welding is an important process in the production and laying of oil and gas pipeline steel pipes. Multi-pass welding is widely used in pipeline manufacturing and field girth welding [5][6][7][8][9]. Compared to the base material, the thermal cycle experiences a series of peak temperatures during welding that can alter the microstructure and properties in the heat-affected zone (HAZ).…”

Section: Introductionmentioning

confidence: 99%

Effect of Nb Content and Second Heat Cycle Peak Temperatures on Toughness of X80 Pipeline Steel

Chen,

Yang,

et al. 2023

Materials

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The microstructure evolution and variation of impact toughness in the heat-affected zone (HAZ) of X80 pipeline steel with different Nb content under different peak temperatures in the secondary thermal cycle were studied through welding thermal simulation, the Charpy impact test, EBSD analysis, SEM observation, and TEM observation in this study. The results indicate that when the peak temperatures of the second pass were lower than Ac1, both X80 pipeline steels had high impact toughness. For secondary peak temperatures in the range of Ac1 to Ac3, both X80 pipeline steels had the worst impact toughness, mainly due to the formation of massive blocky M-A constituents in chain form on grain boundaries. When the secondary peak temperatures were higher than Ac3, both X80 pipeline steels had excellent impact toughness. Smaller grain size and higher proportions of HAGBs can effectively improve the impact toughness. Meanwhile, high Nb X80 pipeline steel had higher impact absorption energy and smaller dispersion. Adding an appropriate amount of Nb to X80 pipeline steel can ensure the impact toughness of SCCGHAZ and SCGHAZ in welded joints.

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Section: Introductionmentioning

confidence: 99%

Effect of Nb Content and Second Heat Cycle Peak Temperatures on Toughness of X80 Pipeline Steel

Chen,

Yang,

et al. 2023

Materials

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Study on the Microstructural and Proficiencies of Heat‐Affected Zone in High‐Slope Mountainous Welded Pipeline Steels

Sui,

Huang,

Chang

et al. 2024

steel research int.

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The failure rate of pipelines in mountainous areas is much higher than that in other service areas. To ensure the efficiency and quality of the project, automatic welding has become a development trend. The heat‐affected zone (HAZ) as a weak area, to a large extent, reflects the quality of welded joints. Herein, the microstructure and mechanical properties of HAZ on both sides of welded joints under a 30° large slope are characterized by high‐resolution transmission electron microscopy, electron backscattered diffraction, and Charpy impact. The results show that the properties of HAZ are affected by many strengthening mechanisms such as grain refinement, solid solution, dislocation, and precipitation, among which grain refinement plays a leading role. The slope will affect the NbC phase size and grain size, resulting in differences in HAZ properties on both sides. The grain size of each microzone in the lower side HAZ is coarsened compared to the higher side, and the dislocation density is lower, leading to a decrease in hardness and impact toughness, thus becoming the weakest region in the welded joint. Therefore, for welding under the condition of slope, attention must be paid to the influence of slope on the performance of welded joints.

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The effect of pipeline root weld microstructure on crack growth behaviour

Fan,

Shuai,

Shuai

et al. 2024

Engineering Failure Analysis

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Comparative study of microstructure and toughness of automatic welded joints of X70 pipeline steel with no slope and 25° slope

Cited by 8 publications

References 20 publications

Effect of Nb Content and Second Heat Cycle Peak Temperatures on Toughness of X80 Pipeline Steel

Effect of Nb Content and Second Heat Cycle Peak Temperatures on Toughness of X80 Pipeline Steel

Study on the Microstructural and Proficiencies of Heat‐Affected Zone in High‐Slope Mountainous Welded Pipeline Steels

The effect of pipeline root weld microstructure on crack growth behaviour

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