Microstructural investigation of friction stir welded pure titanium

Lee, Wonbae; Lee, Chang-Young; Chang, Woong-Seong; Yeon, Yun-Mo; Jung, Seung‐Boo

doi:10.1016/j.matlet.2005.05.064

Cited by 192 publications

(116 citation statements)

References 10 publications

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“…Friction stir welding (FSW) as a solid state welding process is one of the most promising techniques for joining sheets and thin plates made of titanium alloys, avoiding a large number of difficulties arising from the use of fusion welding processes, and could be used for the manufacturing of large size components for aerospace applications [3][4][5][6]. Moreover, FSW could also be used as an alternative manufacturing technology for the fabrication of hollow components made of Ti alloys which are traditionally produced by a combination of diffusion bonding and superplastic forming [7,8]. Details regarding the principles of the FSW process are well discussed in other publications [6,7].…”

Section: Introductionmentioning

confidence: 99%

Tool Wear Characteristics and Effect on Microstructure in Ti-6Al-4V Friction Stir Welded Joints

Fall

Fesharaki

Khodabandeh

et al. 2016

Metals

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Abstract:In the present paper, tool wear and the rate of wear during friction stir welding (FSW) of Ti-6Al-4V alloy are investigated. A conical tungsten carbide tool was used to produce butt-type friction stir welded joints in two-millimeter thick Ti-6Al-4V sheets. An original design of a movable pin allowed for the examination of the tool damage for each process condition. The influence of tool degradation on the quality of the welded joints and the damage brought to the microstructure are examined and discussed. For this purpose, optical and scanning electron microscopies as well as EDX analyses were used to examine the tool wear and the resulting macrostructures and microstructures. The type and nature of the defects are also analyzed as a function of FSW processing parameters. Important geometry and weight variations were observed on the pin and shoulder for all welding conditions, in particular when low tool rotation and travel speeds were used. Experimental results also show that the radial wear of the pin is not uniform, indicating the presence of important frictional temperature gradients through the thickness of the joint. The maximum wear was measured at a location of about one millimeter from the pin root center. Finally, tool rotation was determined as the most significant process parameter influencing both tool wear and microstructure of the joints.

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Section: Introductionmentioning

confidence: 99%

Tool Wear Characteristics and Effect on Microstructure in Ti-6Al-4V Friction Stir Welded Joints

Fall

Fesharaki

Khodabandeh

et al. 2016

Metals

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“…FSW has mostly been applied as a solid-state welding technique to lightweight and low-melting-point materials such as Al 1,2 and Mg. 3,4 However, recently, FSW has been tested on materials that are strong and have a high melting point. [5][6][7][8][9] Some studies on FSW have also investigated the microstructure and 1 mechanical properties of pure Ti and Ti alloys; 5,[10][11][12][13][14][15] however, there is still a considerable gap in knowledge about this topic. The Ti-6Al-4V alloy is extremely hard and undergoes allotropic transformation; it also exhibits considerable microstructural evolution during FSW.…”

Section: Introductionmentioning

confidence: 99%

Effect of tool rotational speed on mechanical properties and microstructure of friction stir welding joints within Ti–6Al–4V alloy sheets

Lee

Baik

2017

Advances in Mechanical Engineering

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Friction stir welding of Ti-6Al-4V alloy sheets was successfully performed with a tungsten carbide (WC) tool, and the effect of the tool rotational speed on the microstructure and mechanical properties of the joints was evaluated. The microstructure was investigated using field emission scanning electron microscopy, electron backscattered diffraction and X-ray diffraction measurements. Tensile, Charpy impact and Vickers hardness tests were performed to evaluate the joints' mechanical properties. The process peak temperature of each welding condition was measured at the bottom of a specimen. Regardless of the welding conditions, the alpha (a) and alpha prime (a 0 ) phases were detected in the stir zone, whereas the base metal was composed of alpha (a) and beta (b) phases. The tensile strength and hardness of the stir zone increased as the tool rotational speed increased. The impact absorption energy was found to be equal to that of the base metal. Moreover, a phase transformation from the b to the a 0 phases occurred in the stir zone during friction stir welding and the evolution of the microstructure in the stir zone significantly affected the mechanical properties of the joints.

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“…The use of conventional fusion welding of titanium leads to the formation of brittleness, distortion and high residual stresses. Therefore, solid state joining processes are more appropriate to avoid problems caused by melting and freezing [7][8].…”

Section: Introductionmentioning

confidence: 99%

Friction Stir Welding of Dissimilar Joints Between Commercially Pure Titanium Alloy and 7075 Aluminium Alloy

2017

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SummaryIn this study, a joint between commercially pure titanium alloy and 7075 aluminium alloy was butt welded by using friction stir welding at a rotational speed of 1120 rpm and a traverse speed of 50 mmmin -1 . The evaluation of hardness and microstructure was performed by using scanning electron microscopy. The phases in the weld area were identified by applying the X-ray diffraction technique and the Energy Dispersive X-ray Spectroscopy (EDS) analysis was used for the evaluation of intermetallic compounds of the weld area. The weld zone is cone-shaped and consists of aluminium and titanium particles that play an important role in increasing hardness and tensile strength. The weld area has three zones, namely the titanium base metal zone, the aluminium base metal zone, and the titanium-aluminium intermetallic compound mixed zone. It was also observed that the joint area on the aluminium side includes the stirred area, the thermo-mechanically affected zone, and the heat-affected zone, while the titanium joint area contains the stirred zone and the heat-affected zone. The hardness value of the weld area was around 360 HV, which means that in this area, compared to the base metal of titanium and aluminium, hardness has increased by 6% and 20%, respectively. This can be attributed to severe plastic deformation and formation of intermetallic compounds of titanium and aluminium in this area.

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Microstructural investigation of friction stir welded pure titanium

Cited by 192 publications

References 10 publications

Tool Wear Characteristics and Effect on Microstructure in Ti-6Al-4V Friction Stir Welded Joints

Tool Wear Characteristics and Effect on Microstructure in Ti-6Al-4V Friction Stir Welded Joints

Effect of tool rotational speed on mechanical properties and microstructure of friction stir welding joints within Ti–6Al–4V alloy sheets

Friction Stir Welding of Dissimilar Joints Between Commercially Pure Titanium Alloy and 7075 Aluminium Alloy

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