Fatigue Assessment of Friction Stir Welded DH36 Steel

Toumpis, Athanasios; Galloway, Alexander; Polezhayeva, Helena; Molter, Lars

doi:10.1002/9781119093343.ch2

Cited by 4 publications

(10 citation statements)

References 5 publications

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“…Despite the existence of defects in FSW joints, the process is still competitive to fusion welding techniques such as SAW. An example of that is found in a study carried out on FSW of DH36 steel in which fatigue resistance of FSW joints was reported to be acceptable and in the range of standard welded joints despite the existence of defects [9] . Threadgill 2007 [114] investigated flaws associated with FSW and did not consider them defects as the FSW samples were still meeting the mechanical test standards.…”

Section: Fsw Defectsmentioning

confidence: 97%

“…There are also no elements lost during the process, the mechanical properties such as tensile strength [8] and especially fatigue resistance [9] are increased after welding.…”

Section: 21advantagesmentioning

confidence: 99%

“…Toumpis et al 2015 [9] examined the evolution of mechanical properties of FSW DH36 steel Konkol and Mruczek 2007 , [23] studied the feasibility of FSW HSLA-65 steel 6mm plate thickness and compared the produced weld joints with SAW in term of distortion and microstructure evolution. FSW samples showed no transverse distortion, higher toughness and tensile strength than SAW samples.…”

Section: Microstructure Evolution and Mechanical Properties In Fsw Ofmentioning

confidence: 99%

“…AutoCAD drawings as shown in Figure 3.4 and Figure 3.5 were produced in order to determine the steady state region of the FSW so that material from this region could be examined. The sample dimension for fatigue and tensile testing according to EN-BS 895:1995 and BS 7270 [9] are shown in The tensile test samples were taken from the steady state region according to the British Standard EN-BS 895:1995 [182] . .5MPa were used [9] .…”

Section: Specimen Preparation (Fsw Dh36 Steel) For Tensile and Fatigumentioning

confidence: 99%

“…The sample dimension for fatigue and tensile testing according to EN-BS 895:1995 and BS 7270 [9] are shown in The tensile test samples were taken from the steady state region according to the British Standard EN-BS 895:1995 [182] . .5MPa were used [9] . Stress frequency was kept constant at 10Hz during the testing program.…”

Section: Specimen Preparation (Fsw Dh36 Steel) For Tensile and Fatigumentioning

confidence: 99%

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A mathematical and experimental analysis of friction stir welding of steel

Al-moussawi¹

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In the last decade there has been significant research into joining steel alloys using the Friction Stir Welding technique due to its ability to carry out welding below the melting point of the parent material and without using fillers such as in fusion welding techniques. This coincided with the increased use of DH36 and EH46 steel grades for ship building. The main reason for joining these steel grades by the friction stir welding technique is to reduce the weight of the vessel, as well as, the high welded joint quality especially mechanical properties such as fatigue and impact resistance. Other improved physical characteristics include increased tensile strength, microhardness and surface finish. This research project has attempted to model friction stir welding using Computational Fluid Dynamics (CFD). Three different approaches have been used when considering the interface between the tool and the workpiece; these are torque, sticking/slipping and fully sticking. The project also investigates the mechanical properties of the welded joints including tensile, fatigue and microhardness. The microstructural evolution of welded joints carried out using different welding parameters is also investigated. The phenomenon of elemental precipitation/segregation during the friction stir welding process has been investigated and the limit of tool rotational speed at which the segregation occurs has been determined by modelling and also by heat treatment to simulate FSW. The purpose of the heat treatment trials was to attempt to replicate the temperature and time that the parent materials experiences during the FSW process. Defects in the weld joints associated with unsuitable friction stir welding parameters were also investigated and two new types of defect have been identified for the first time. Finally, tool wear has been investigated in the different weld joints in order to understand the suitable welding parameters that can prolong tool life. IV Project Outcomes and Cooperation The following journal and conference papers have been published as part of the project outcomes. Conference Presentations.

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Section: Fsw Defectsmentioning

confidence: 97%

“…There are also no elements lost during the process, the mechanical properties such as tensile strength [8] and especially fatigue resistance [9] are increased after welding.…”

Section: 21advantagesmentioning

confidence: 99%

Section: Microstructure Evolution and Mechanical Properties In Fsw Ofmentioning

confidence: 99%

Section: Specimen Preparation (Fsw Dh36 Steel) For Tensile and Fatigumentioning

confidence: 99%

Section: Specimen Preparation (Fsw Dh36 Steel) For Tensile and Fatigumentioning

confidence: 99%

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A mathematical and experimental analysis of friction stir welding of steel

Al-moussawi¹

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Defects in Friction Stir Welding of Steel

Al-moussawi

Smith

2018

Metallogr. Microstruct. Anal.

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Defects associated with friction stir welding of two steel grades including DH36 and EH46 were investigated. Different welding parameters including tool rotational and tool traverse (linear) speeds were applied to understand their effect on weld seam defects including microcracks and voids formation. SEM images and infinite focus microscopy were employed to identify the defects types. Two new defects associated with the friction stir welding process are introduced in this work. The first defect identified in this work is a microcrack found between the plunge and the steady state region and attributed to the traverse moving of the tool with unsuitable speed from the plunge-dwell to the steady state stage. The tool traverse speed has recommended to travel 20 mm more with accelerated velocity range of 0.1 from the maximum traverse speed until reaching the steady state. The maximum recommended traverse speed in the steady state was also suggested to be less than 400 mm/min in order to avoid the lack in material flow. The second type of defect observed in this work was microcracks inside the stirred zone caused by elemental precipitations of TiN. The precipitates of TiN were attributed to the high tool rotational speed which caused the peak temperature to exceed 1200°C at the top of the stirred zone and based on previous work. The limit of tool rotational speed was recommended to be maintained in the range of 200-500 RPM based on the mechanical experiments on the FSW samples.

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Numerical optimisation of laser assisted friction stir welding of structural steel

Ahmad

Galloway

Toumpis

2019

Science and Technology of Welding and Joining

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Significant progress has been made on the implementation of friction stir welding (FSW) in the industry for aluminium alloys. However, steel FSW and other high temperature alloys is still the subject of considerable research, mainly because of the short life and high cost of the FSW tool. Different auxiliary energies have been considered as a means of optimising the FSW process and reducing the forces on the tool during the plunge and traverse stages, but numerical studies on steel are particularly limited. Building on the state-of-art, laser assisted steel FSW has been numerically developed and analysed as a viable process amendment. Laser assisted FSW increased the traverse speed up to 1500 mm/min, significantly higher than conventional steel FSW. The application of laser assistance with a distance of 20 mm from the rotating tool reduced the reaction force on the tool probe tip up to 55% as compared to standard FSW.

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Fatigue Assessment of Friction Stir Welded DH36 Steel

Cited by 4 publications

References 5 publications

A mathematical and experimental analysis of friction stir welding of steel

A mathematical and experimental analysis of friction stir welding of steel

Defects in Friction Stir Welding of Steel

Numerical optimisation of laser assisted friction stir welding of structural steel

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