Effect of rotation rate on microstructure and texture evolution during friction stir welding of Ti–6Al–4V plates

Yoon, Shin-Eui; Ueji, Rintaro; Fujii, Hidetoshi

doi:10.1016/j.matchar.2015.06.025

Cited by 68 publications

(26 citation statements)

References 31 publications

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“…The lower heat input condition showed a lower maximum intensity (Imax) in the entire weld, however, the area includes a lamellar structure (A in the 150 rpm joint) which showed a higher texture intensity. Yoon et al (2015) already pointed out that the areas include lamellar structure exhibited a higher texture intensity in the FSW joints of the Ti-6Al-4V alloy. The maximum texture intensity increases when the thermal cycle of the FSW includes the phase transformation to the lamellar structure probably due to the variant selection effect.…”

Section: Structure Distribution In Thicknessmentioning

confidence: 91%

“…This grain size distribution in thickness should be due to the temperature gradient. Yoon et al (2015) has already clarified the grain size distribution in thickness of the Ti-6Al-4V alloy joints and the distribution should be due to the temperature gradient caused by the lower thermal conductivity. The mean equiaxed α grain size in the top, the center and the bottom part of the SZ was 1.5, 1.2 and 0.7 ㎛, respectively.…”

Section: Structure Distribution In Thicknessmentioning

confidence: 99%

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Microstructure and texture distribution of Ti–6Al–4V alloy joints friction stir welded below β-transus temperature

Yoon

Ueji

Fujii

2016

Journal of Materials Processing Technology

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Ti-6Al-4V alloy plates with a thickness of 5 mm were successfully joined by friction stir welding (FSW) at a significantly lower than the β-transus temperature, and the microstructure and texture evolution in the stir zone (SZ) along the thickness and transverse directions of the joint were clarified. The fully equiaxed α structure was observed even near the top surface in the 50 rpm joint, while a mixture of the lamellar structure with equiaxed α grains was found near the top surface in the 150 rpm joint. The existence of the lamellar structure resulted in a strong [0001]α concentration in this area due to the variant selection during the phase transformation. A bimodal structure was formed in the retreating side (RS) of the SZ obtained at 50 rpm, and a higher area fraction of the coarse grain structure was found in the RS of the SZ center than in the RS located 0.1 mm from the top surface due to the gradients in the strain, strain rate and temperature. The local texture measured by EBSD clarified that [0001]α was perpendicular to the welding direction on the advancing side (AS), and gradually rotated toward to the welding direction when the measurement positions were moved to the RS in the SZ of the Ti alloy joints. The difference in the distribution of the [0001]α concentration direction in

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Section: Structure Distribution In Thicknessmentioning

confidence: 91%

Section: Structure Distribution In Thicknessmentioning

confidence: 99%

Microstructure and texture distribution of Ti–6Al–4V alloy joints friction stir welded below β-transus temperature

Yoon

Ueji

Fujii

2016

Journal of Materials Processing Technology

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“…The former has been discussed by Lienert [9] and also the authors' previous paper [23] in which the reason for the distribution is mainly due to the temperature gradient in the thickness. The lower temperature with plastic deformation provides a finer microstructure via recrystallization and grain growth.…”

Section: Microstructure Evolution Of Weldmentioning

confidence: 93%

Effect of initial microstructure on Ti–6Al–4V joint by friction stir welding

2015

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Ti-6Al-4V alloy plates with three types of initial microstructures, which have different densities of the high angle boundaries, were joined by friction stir welding (FSW), and the microstructure evolution in the stir zone by the FSW was clarified. Concerning the morphology of the microstructure, all three joints show similar characteristics; the top surface of the SZs exhibited a mixture of the lamellar structure with equiaxed α grains and the area fraction of the equiaxed α grain gradually increased with the increasing distance from the top surface due to the temperature gradient. On the other hand, the mean α grain size of the fully equiaxed α structure area decreased with the increasing initial density of high angle boundaries. This accelerated grain refinement was discussed based on the effect of the inhomogeneous microstructure on the recrystallization.

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“…Thus, a new set of fine grains are observed in the stir zones of the joints fabricated using THC and TTC tools in both the cooling conditions. In the TMAZ, the heat input and the deformation is not sufficient to recrystallize the grains (Yoon et al 2015). Thus, elongated coarse grains are observed in both the joints.…”

Section: The Effect Of Tool Pin Profiles On Microstructurementioning

confidence: 98%

The effect of pin profiles on the microstructure and mechanical properties of underwater friction stir welded AA2519-T87 aluminium alloy

Sabari

Malarvizhi

Balasubramanian

2016

Int J Mech Mater Eng

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Background: AA2519-T87 is a new armour grade aluminium alloy employed in the fabrication of light combat military vehicles. Joining of this material using fusion welding processes, results in the formation of solidification defects like porosity, alloy segregation and hot cracking. In order to overcome the solidification related problems, solid state welding processes such as friction stir welding (FSW) can be used. Though the joining takes place below the melting temperature of the material, the thermal cycle experienced by the thermo-mechanical-affected zone (TMAZ) and heat-affected zone (HAZ) is causing grain coarsening and precipitates dissolution in the age-hardenable aluminium alloys, which deteriorate the joint properties. To get rid of this problem, underwater friction stir welding (UWFSW) process can be employed. The water cooling reduces the heat, and thus, the thermal softening required taking place in TMAZ and HAZ. Therefore, the material flow is entirely different in FSW and UWFSW.

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Effect of rotation rate on microstructure and texture evolution during friction stir welding of Ti–6Al–4V plates

Cited by 68 publications

References 31 publications

Microstructure and texture distribution of Ti–6Al–4V alloy joints friction stir welded below β-transus temperature

Microstructure and texture distribution of Ti–6Al–4V alloy joints friction stir welded below β-transus temperature

Effect of initial microstructure on Ti–6Al–4V joint by friction stir welding

The effect of pin profiles on the microstructure and mechanical properties of underwater friction stir welded AA2519-T87 aluminium alloy

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