Development of grain structure in β-phase field during friction stir welding of Ti–6Al–4V alloy

Mironov, S.; Zhang, Y.; Sato, Yutaka; Kokawa, Hiroyuki

doi:10.1016/j.scriptamat.2008.02.014

Cited by 98 publications

(66 citation statements)

References 11 publications

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“…For example, the grains were nominally equiaxed in the central stir zone, but tended to be elongated in the local shear direction on the advancing and retreating sides. Similar observations were made by Lienert et al [42] and Mironov et al [14] for friction stir welded Ti-6-4. Mironov et al [14] interpret this as evidence that the grain refinement mechanism is ''elongation and transverse subdivision'' of the b grains.…”

Section: A Stir Zone Microstructuressupporting

confidence: 90%

“…Similar observations were made by Lienert et al [42] and Mironov et al [14] for friction stir welded Ti-6-4. Mironov et al [14] interpret this as evidence that the grain refinement mechanism is ''elongation and transverse subdivision'' of the b grains. These observations were made on the advancing and retreating side transition zones both inside and outside what the authors demarcated as the stir zone border.…”

Section: A Stir Zone Microstructuressupporting

confidence: 90%

“…In contrast to both of these studies, Mironov et al [14] invoked two different recrystallization mechanisms to explain two different types of b grain morphology during FSW of Ti-6-4 above the b transus. The first was discontinuous recrystallization stimulated by local grain boundary migration, which formed fine scale b grains in the stir zone.…”

Section: A Review Of Grain Refinement During Fsw and Processing Of Amentioning

confidence: 98%

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Microstructure and Texture Evolution during Friction Stir Processing of Fully Lamellar Ti-6Al-4V

Pilchak

Williams

2010

Metall Mater Trans A

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Friction stir processing (FSP) was used to locally refine a thin surface layer of the coarse, fully lamellar microstructure of investment-cast Ti-6Al-4V. Depending on the peak temperature reached in the stir zone during processing relative to the b transus, three distinct classes of microstructures were observed. Using accepted wrought product terminology, they are equiaxed, bimodal, and lamellar, except for the case of FSP, the length scale of each was smaller by at least an order of magnitude compared to typical wrought material. The evolution of an initially strain-free fully lamellar microstructure to each of these three refined conditions was characterized with scanning electron microscopy, transmission electron microscopy and electron backscatter diffraction. The fundamental mechanisms underlying grain refinement during FSP, including both the morphological changes and the formation of high-angle grain boundaries, were discussed.

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Section: A Stir Zone Microstructuressupporting

confidence: 90%

Section: A Stir Zone Microstructuressupporting

confidence: 90%

Section: A Review Of Grain Refinement During Fsw and Processing Of Amentioning

confidence: 98%

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Microstructure and Texture Evolution during Friction Stir Processing of Fully Lamellar Ti-6Al-4V

Pilchak

Williams

2010

Metall Mater Trans A

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“…In the last three decades, friction stir welding has emerged as a new welding technology, and was adapted for welding thin sheets, not only for butt joints but also lap joints. However, owing to the high melting point of titanium alloy and the high contact forces between metal sheets and the friction tool, the choice of friction tool material is difficult and limited [16][17][18].…”

Section: Methodsmentioning

confidence: 99%

Characteristics of Resistance Spot Welded Ti6Al4V Titanium Alloy Sheets

Zhang

Chen

et al. 2017

Metals

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Ti6Al4V titanium alloy is applied extensively in the aviation, aerospace, jet engine, and marine industries owing to its strength-to-weight ratio, excellent high-temperature properties and corrosion resistance. In order to extend the application range, investigations on welding characteristics of Ti6Al4V alloy using more welding methods are required. In the present study, Ti6Al4V alloy sheets were joined using resistance spot welding, and the weld nugget formation, mechanical properties (including tensile strength and hardness), and microstructure features of the resistance spot-welded joints were analyzed and evaluated. The visible indentations on the weld nugget surfaces caused by the electrode force and the surface expulsion were severe due to the high welding current. The weld nugget width at the sheets' faying surface was mainly affected by the welding current and welding time, and the welded joint height at weld nugget center was chiefly associated with electrode force. The maximum tensile load of welded joint was up to 14.3 kN in the pullout failure mode. The hardness of the weld nugget was the highest because of the coarse acicular α structure, and the hardness of the heat-affected zone increased in comparison to the base metal due to the transformation of the β phase to some fine acicular α phase.

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“…Ref. [7][8][9] pointed that on cooling after -transform during Friction stir welding (FSW) or FSP, -Ti can nucleate at triple-points to grain-boundary (GB), coarsen to cover the prior-GBs, and grow from the formed GB-into t he neighboring prior-grains with Burgers orientation relation. Thus, the final microstructure of regions containing GB -and acicular was formed (Fig.2d).…”

Section: Introductionmentioning

confidence: 99%

Microstructural Characteristics of Surface Composite on Titanium Alloy Fabricated via a Novel Method of Friction-Stir Nitriding

Li¹

2016

Proceedings of the 2015 2nd International Forum on Electrical Engineering and Automation (IFEEA 2015)

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Abstract. The microstructural evolutions and properties of the surface composite produced via the friction stir nitriding (FSN) method on Ti-6Al-4V alloy were investigated. Due to the optimized process parameters and suitable mixed gas proportion for a limited combustion reaction between Ti and N 2 , a composite layer with the thickness of ~200 m beneath an outermost thin TiN layer was fabricated. The composite layer was composed of three microstructure types. Formation mechanisms for microstructure evolutions during FSN on titanium alloy were detailed in terms of three steps. IntroductionTitanium alloys would have much wider usage in various industrial sectors if their wear-resistance could be significantly improved [1]. To solve this problem, the surface micro-structure of titanium can be modified via nitriding techniques, such as plasma, laser, and gas nitriding [2]. The nitrogen has a high solubility in -Ti to significantly strengthen the surface layer due to the formation of the compound layer containing of TiN and/or Ti 2 N [2]. In the present paper, a novel nitriding method called friction-stir nitriding (FSN) is proposed. Multiple research results announced that friction stir processing (FSP) is emerging as a very attractive method used primarily to provide the localized modification of microstructures in the surface layers of metal components or to in-situ form a wear-resistant composite surface [3][4][5]. Actually, FSN is employed for titanium and its alloys depending on the basic principles of FSP technique and a limited combustion reaction of Ti in a mixed atmosphere of Ar 2 and N 2 gases during FSP procedure. It is well-known that the wearable TiN x compounds can be synthesized via a rapid combustion reaction between Ti and N 2 gas [6]. Interests in this alternative nitriding method of FSN for preparing composite surface layer embedded in the Ti matrix are motivated by low cost production, the considerable surface-layer thickness and no debonding issues due to the inherent material continuity between the treated layer and substrate.

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Development of grain structure in β-phase field during friction stir welding of Ti–6Al–4V alloy

Cited by 98 publications

References 11 publications

Microstructure and Texture Evolution during Friction Stir Processing of Fully Lamellar Ti-6Al-4V

Microstructure and Texture Evolution during Friction Stir Processing of Fully Lamellar Ti-6Al-4V

Characteristics of Resistance Spot Welded Ti6Al4V Titanium Alloy Sheets

Microstructural Characteristics of Surface Composite on Titanium Alloy Fabricated via a Novel Method of Friction-Stir Nitriding

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