Microstructure and Mechanical Properties of Dissimilar Friction Welding Ti-6Al-4V Alloy to Nitinol

Rehman, Ateekh Ur; Babu, N. Kishore; Talari, Mahesh Kumar; Usmani, Yusuf Siraj; Alkhalefah, Hisham

doi:10.3390/met11010109

Cited by 14 publications

(16 citation statements)

References 28 publications

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“…The faster cooling in turn could affect the microstructure in the rotating alloy depending on its sensitivity to such a minor temperature drop. The friction welding experimental procedure has been detailed elsewhere [16]. The welding parameters are listed in Table 2.…”

Section: Experimental Techniquesmentioning

confidence: 99%

Rotary Friction Welding of Inconel 718 to Inconel 600

Rehman

Usmani

Al-Samhan

et al. 2021

Metals

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Nickel-based superalloys exhibit excellent high temperature strength, high temperature corrosion and oxidation resistance and creep resistance. They are widely used in high temperature applications in aerospace, power and petrochemical industries. The need for economical and efficient usage of materials often necessitates the joining of dissimilar metals. In this study, dissimilar welding between two different nickel-based superalloys, Inconel 718 and Inconel 600, was attempted using rotary friction welding. Sound metallurgical joints were produced without any unwanted Laves or delta phases at the weld region, which invariably appear in fusion welds. The weld thermal cycle was found to result in significant grain coarsening in the heat effected zone (HAZ) on either side of the dissimilar weld interface due to the prevailing thermal cycles during the welding. However, fine equiaxed grains were observed at the weld interface due to dynamic recrystallization caused by severe plastic deformation at high temperatures. In room temperature tensile tests, the joints were found to fail in the HAZ of Inconel 718 exhibiting good ultimate tensile strength (759 MPa) without a significant loss of tensile ductility (21%). A scanning electron microscopic examination of the fracture surfaces revealed fine dimpled rupture features, suggesting a fracture in a ductile mode.

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Section: Experimental Techniquesmentioning

confidence: 99%

Rotary Friction Welding of Inconel 718 to Inconel 600

Rehman

Usmani

Al-Samhan

et al. 2021

Metals

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“…As evidenced in the previous paragraphs, fusion [11][12][13][14]17,18] and solid-state welding [9,15,16,19,20] techniques were shown to have been quite successful in joining Nitinol to Nitinol, whereas in dissimilar combination welds, Nitinol was poor at bonding with other materials, such as Ti-6Al-4V [11][12][13][14][15][16]. It has to be noted here that most of these studies concentrated mainly on fusion welding techniques, but not solid-state welding.…”

Section: Schematic Of Base Plates and Their Setup In The Linear Frict...mentioning

confidence: 84%

“…Rehman et al deployed rotary friction welding, another type of solid-state welding, to join Nitinol to Ti-6Al-4V [16]. The joints showed promising strengths of up to 50% of the base metals' strength.…”

Section: Introductionmentioning

confidence: 99%

Characterisation of Microstructure and Mechanical Properties of Linear Friction Welded α+β Titanium Alloy to Nitinol

et al. 2021

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A variable area nozzle integrated into the design of a high-bypass-ratio turbofan engine effectively saves up to 10% in aircraft fuel consumption. Additionally, noise emissions can be lowered at airports during take-off and landing by having better control of the nozzle diameter. Shape memory capabilities of Nitinol alloys could be availed in the form of actuators in the construction of such a nozzle. However, these Nitinol actuators must be joined to Ti-6Al-4V, a prominent alloy making up most of the rest of the nozzle. Because of the huge differences in the physical and metallurgical properties of these alloys, fusion welding is not as effective as solid-state welding. In the current study, a linear friction welding process was adopted to join Ti-6Al-4V to Nitinol successfully. The effect of friction welding on the evolution of weld macro and microstructures; hardness and tensile properties were studied and discussed. The macrostructure of Ti-6Al-4V and Nitinol’s dissimilar joint revealed flash formation mainly on the Ti-6Al-4V side due to its reduced flow strength at high temperatures. Optical microstructures revealed fine grains in Ti-6Al-4V immediately adjacent to the interface due to dynamic recrystallisation and strain hardening effects. In contrast, Nitinol remained mostly unaffected. An intermetallic compound (Ti2Ni) was seen to have formed at the interface due to the extreme rubbing action, and these adversely influenced the tensile strength and elongation values of the joints.

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“…The welding procedure corresponding to the rotary friction welding machine has been explained in ref. [ 18 ]. A typical friction welding cycle comprises five process parameters: friction pressure, burn-off length or friction time, spindle speed, upset pressure, and upset time.…”

Section: Methodsmentioning

confidence: 99%

Influence of Post Weld Heat Treatment on the Grain Size, and Mechanical Properties of the Alloy-800H Rotary Friction Weld Joints

et al. 2021

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This study evaluated the microstructure, grain size, and mechanical properties of the alloy 800H rotary friction welds in as-welded and post-weld heat-treated conditions. The standards for the alloy 800H not only specify the composition and mechanical properties but also the minimum grain sizes. This is because these alloys are mostly used in creep resisting applications. The dynamic recrystallization of the highly strained and plasticized material during friction welding resulted in the fine grain structure (20 ± 2 µm) in the weld zone. However, a small increase in grain size was observed in the heat-affected zone of the weldment with a slight decrease in hardness compared to the base metal. Post-weld solution heat treatment (PWHT) of the friction weld joints increased the grain size (42 ± 4 µm) in the weld zone. Both as-welded and post-weld solution heat-treated friction weld joints failed in the heat-affected zone during the room temperature tensile testing and showed a lower yield strength and ultimate tensile strength than the base metal. A fracture analysis of the failed tensile samples revealed ductile fracture features. However, in high-temperature tensile testing, post-weld solution heat-treated joints exhibited superior elongation and strength compared to the as-welded joints due to the increase in the grain size of the weld metal. It was demonstrated in this study that the minimum grain size requirement of the alloy 800H friction weld joints could be successfully met by PWHT with improved strength and elongation, especially at high temperatures.

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Microstructure and Mechanical Properties of Dissimilar Friction Welding Ti-6Al-4V Alloy to Nitinol

Cited by 14 publications

References 28 publications

Rotary Friction Welding of Inconel 718 to Inconel 600

Rotary Friction Welding of Inconel 718 to Inconel 600

Characterisation of Microstructure and Mechanical Properties of Linear Friction Welded α+β Titanium Alloy to Nitinol

Influence of Post Weld Heat Treatment on the Grain Size, and Mechanical Properties of the Alloy-800H Rotary Friction Weld Joints

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