A comparison between fracture toughness at different locations of longitudinal submerged arc welded and spiral submerged arc welded joints of API X80 pipeline steels

Great thanking to almighty God for giving me the patience and ambitious and blessing me to complete this work. I would like to give my sincere thanks also to my supervisor, professor Dr. Elsadig Mahdi Saad for his supporting, encouraging and advising throughout the thesis preparation, and for his assisting and providing of all necessaries to carry out this work. Finally, yet importantly, I would like to express my thanks and appreciate to the workshop team at Qatar University, Mr. Sunith & Mr. Judith for their help in preparing the pipe samples, and to Eng. Mohamed Karim & Eng. Mohamed Gebril for their exceptional efforts and help in carrying out the experiments. vii TABLE OF CONTENTS

show abstract

“…They concluded that fracture toughness of base metal was the highest compared to HAZ. (Chen, Lu, Chen, & Wang, 2015).…”

Section: Wz Haz Hazmentioning

confidence: 99%

New approach of pipelines joining using fiber reinforced plastics composites

Farag

Mahdi

2019

Composite Structures

View full text Add to dashboard Cite

show abstract

“…In addition, various welding parameters such as heat input, cooling time, preheat temperature and groove design significantly affects joint properties. 6 Previous studies have reported that high heat input increases the size of HAZ and impairs the resulting fracture toughness. [5][6][7] As per Dhua et al, 8 heat input (2 kJ/mm) has a significant effect on the toughness of HAZ.…”

Section: Introductionmentioning

confidence: 99%

“…Extensive literature has expressed concern that microstructural transformations occur in HAZ during welding, which exhibits degraded mechanical behaviour in highstrength low-alloy steels. [5][6][7][8][9][10][11][12][13] As per peak temperature experienced, subzones of HAZ has been classified, namely, coarse grain HAZ (CGHAZ ≥ 1200 C), fine grain HAZ (FGHAZ ≥ Ac 3 ) and intercritical HAZ (Ac 1 ≤ ICHAZ ≥ Ac 3 ) depending on their relative distance from the centre of the weld zone and peak temperatures. 14 Earlier studies have documented that fusion line and CGHAZ possessed poor combination of strength and toughness resulting in immature failure of welded joints.…”

Section: Introductionmentioning

confidence: 99%

Influence of heat input on microstructure and fracture toughness property in different zones of X80 pipeline steel weldments

Singh

Arora

Kumar

et al. 2020

Fatigue Fract Eng Mat Struct

View full text Add to dashboard Cite

In this paper, microstructure observations and mechanical behaviour of fusion line and offsetting positions from fusion line by 1, 2 and 3 mm were analysed. For the welding of X80 pipeline steel plates, different magnitudes of heat inputs such as high heat input (HHI) 25 kJ/cm, medium heat input (MHI) 20 kJ/cm and low heat input (LHI) 15 kJ/cm were employed. Critical values of J-integral (J 0.2) and crack tip opening displacement (CTOD 0.2) for predetermined regions in the X80 weldment were determined as per ASTM-E1820a. M-A constituents of different sizes such as small (1-2 μm), large >2 μm and slender (>4 μm) were observed in the microstructure of subzones of weldments for different heat inputs. Formation of granular bainite, M-A constituents and inclusions of Ti, Si, Mo in the microstructure impaired fracture toughness property. In the X80 weldment, the fusion line (FL) for HHI was found weakest in terms of fracture resistance, which subsequently increases the risk of fracture.

show abstract

“…Longitudinal submerged arc welded pipes use for long-distance transport of oil and gas [1], especially in harsh seismic zone [2], tundra, and high drop terrain [3]. At present, the development of the pipeline steel strength is meaningless only by the improvement of the toughness, weldability, and corrosion resistance of the steel correspondingly increases.…”

Section: Introductionmentioning

confidence: 99%

Mechanical properties and microstructure of longitudinal submerged arc welded joint of a new C–Mn steel sheet cladding fine grained ferrite in surface layer for a long distance transport pipeline

Fan

Luo

Gao

et al. 2020

Mater. Res. Express

View full text Add to dashboard Cite

A new type of C-Mn pipeline steel plates with the ult5ra-fine grained ferrite in surface layer and the fine-grained ferrite in the central layer has been developed successfully. In order to manufacture the long distance oil pipelines using this new ultra-fine grain pipeline steel sheet, the microstructure and mechanical properties of the welded joints by the Longitudinal Submerged Arc Welding (LSAW), especially the impact toughness, need to be evaluated. Tensile tests, impact tests, are used to study the mechanical properties in this paper according the Chinese National standards. The metallographic technique and SEM are adapted to analyze the microstructure and impact fracture morphology of the LSAW joint. The research results show that the HAZ near the fusion line is a weak part of impact toughness of LSAW joint. However, the base metal is of the fine-grained and ultra-fine grained microstructure itself, and the heat treatment effects between the post-process welding seam and preprocess welding seam on the multi-layer and multi-pass submerged arc welding process, the impact toughness of the HAZ is greatly improved. The whole welded joint is better than the performance of ordinary pipeline steel, which is satisfied with the welding performance requirements of steel sheet engineering application, and can be used in long distance pipeline manufacturing projects.

show abstract

A comparison between fracture toughness at different locations of longitudinal submerged arc welded and spiral submerged arc welded joints of API X80 pipeline steels

Cited by 36 publications

References 25 publications

New approach of pipelines joining using fiber reinforced plastics composites

New approach of pipelines joining using fiber reinforced plastics composites

Influence of heat input on microstructure and fracture toughness property in different zones of X80 pipeline steel weldments

Mechanical properties and microstructure of longitudinal submerged arc welded joint of a new C–Mn steel sheet cladding fine grained ferrite in surface layer for a long distance transport pipeline

Contact Info

Product

Resources

About