An Experimental Evaluation of Electron Beam Welded Thixoformed 7075 Aluminum Alloy Plate Material

Chegeni, Ava Azadi; Kapranos, P.

doi:10.3390/met7120569

Cited by 6 publications

(3 citation statements)

References 18 publications

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“…Aluminum alloys with high amounts of alloying elements and extended mushy zone, such as Al2024 and Al7075, are more prone to weld solidification cracking [4]. So far, several investigations have been conducted to address this challenge for a variety of processes, including resistance welding [5,6], metal inert gas (MIG) welding [7,8], tungsten inert gas (TIG) welding [7,[9][10][11], laser welding [11,12], and electron beam welding [13,14]. Among effective approaches demonstrated so far are welding parameters optimization [7,10,15], using pulsed current instead of continuous current in arc welding [16,17], as well as switching from fusion welding to solid state welding methods such as friction welding [18] and friction stir welding [19,20].…”

Section: Introductionmentioning

confidence: 99%

An adapted approach for solidification crack elimination in Al7075 TIG welding

Abdollahi,

Nganbe,

Kabir

2024

Mater. Res. Express

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Solidification cracking is a long-standing issue in fusion welding of high-strength aluminum alloys like Al7075, imposing limitations on their aerospace and automotive applications. The current study introduces a novel adapted approach in solidification crack elimination by incorporating TiC nanoparticles into the fusion zone using a filler paste as an easier to fabricate alternative to filler metals investigated so far. To assess the weldability of the proposed method, 3-mm thick Al7075 sheets were TIG welded (i) autogenously without any TiC nanoparticles (autogenous), (ii) heterogeneously using 1 vol.% TiC-nanoparticle enhanced Al7075 filler metal (heterogeneous filler metal), and (iii) heterogeneously using an in-house fabricated Al7075 paste containing 1 vol.% TiC nanoparticles (heterogeneous filler paste). Macroscopic analysis of weld specimens proved that both heterogeneous welding approaches effectively eliminated solidification cracks. This was confirmed by Houldcroft solidification susceptibility index deduction tests that demonstrated a strong reduction in solidification crack susceptibly in all heterogeneous joints as compared to the autogenous joint. Microstructural analysis confirmed the transformation from columnar to equiaxed grain morphology in the fusion zone as crucial factor in crack elimination. Overall, the proposed filler paste method represents a highly cost-efficient approach for eliminating solidification cracks in TIG joining of difficult to weld aluminium alloys.

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Section: Introductionmentioning

confidence: 99%

An adapted approach for solidification crack elimination in Al7075 TIG welding

Abdollahi,

Nganbe,

Kabir

2024

Mater. Res. Express

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“…The microstructure of the electron beam welded joints differs in the heat-affected zone and the weld bead, which are observed in titanium alloys, aluminum alloys, and nickel-based alloys of welded joints [11,14,15,16]. Interestingly, despite the vacuum condition used in the welding process, the welding defects in the form of the welded pores and inclusions are still observed in the welded joints.…”

Section: Introductionmentioning

confidence: 99%

Influence of Welded Pores on Very Long-Life Fatigue Failure of the Electron Beam Welding Joint of TC17 Titanium Alloy

et al. 2019

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The electron beam welding process is widely used in the connection among titanium alloy material parts of aero-engines. Its mechanical properties need to meet the requirements of long life and high reliability. In this paper, the static strength and the fatigue failure behavior of the electron beam weldments of TC17 titanium alloy were investigated experimentally under low amplitude high frequency (20 kHz), and the mechanical response and failure mechanism under different external loading conditions were analyzed. In summary, the samples were found to have anisotropic microstructure. The tensile strength of the PWHT of TC17 EBW joint was ~4.5% lower than that of the base metal. Meanwhile, compared with the base metal, the fatigue strength was reduced by 45.5% at 109 cycles of fatigue life. The fracture analysis showed that the fatigue failure of the welded joint of TC17 alloy was caused by the welded pores and the fatigue cracks initiated from the welded pores. A fine granular area (FGA) was observed around the crack initiation region. The existence of pores caused the stress intensity factor of the fine granular area (KFGA) to be inversely proportional to the fatigue life. The KFGA calculation formula was modified and the fatigue crack propagation threshold of the welded joint of TC17 alloy was calculated (3.62 MPa·m1/2). Moreover, the influences of the effective size and the relative depth of the pores on the very long fatigue life of the electron beam welded joint of TC17 titanium alloy were discussed.

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“…Therefore, an innovative route that can avoid the above mentioned problems inherent in fusion welding is required. Thixojoining is a possible technique that can weld the AISI D2 cold-work tool steel free from the above mentioned problems, as the process is carried at the semisolid state where the mechanisms of solidification and heat flow are different from other welding processes [2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Microstructure and Mechanical Properties of Thixowelded AISI D2 Tool Steel

Mohammed

Omar

Al-Zubaidi

et al. 2018

Metals

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Rigid perpetual joining of materials is one of the main demands in most of the manufacturing and assembling industries. AISI D2 cold work tool steels is commonly known as non-weldable metal that a high quality joint of this kind of material can be hardly achieved and almost impossible by conventional welding. In this study, a novel thixowelding technology was proposed for joining of AISI D2 tool steel. The effect of joining temperature, holding time and post-weld heat treatment on microstructural features and mechanical properties were also investigated. Acceptable joints without defect were achieved through the welding temperature of 1300 • C, while the welding at lower temperature resulted in a series of cracks across the entire joint that led to spontaneous fracture after joining. Tensile test results showed that maximum joint tensile strength of 271 MPa was achieved at 1300 • C and 10 min holding time, which was 35% of that of D2 base metal. Meanwhile, tensile strength of the joined parts after heat treatment showed a significant improvement over the non-heat treated condition with 560 MPa, i.e., about 70% of that of the strength value of the D2 base metal. This improvement in the tensile strength attributed to the dissolution of some amounts of eutectic chromium carbides and changes in the microstructure of the matrix. The joints are fractured at the diffusion zone, and the fracture exhibits a typical brittle characteristic. The present study successfully confirmed that by avoiding dendritic microstructure, as often resulted from the fusion welding, high joining quality components obtained in the semi-solid state. These results can be obtained without complex or additional apparatuses that are used in traditional joining process.

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An Experimental Evaluation of Electron Beam Welded Thixoformed 7075 Aluminum Alloy Plate Material

Cited by 6 publications

References 18 publications

An adapted approach for solidification crack elimination in Al7075 TIG welding

An adapted approach for solidification crack elimination in Al7075 TIG welding

Influence of Welded Pores on Very Long-Life Fatigue Failure of the Electron Beam Welding Joint of TC17 Titanium Alloy

Microstructure and Mechanical Properties of Thixowelded AISI D2 Tool Steel

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