Understanding the mechanical behaviour of 718 and 625 + nickel based super-alloys under cathodic polarization

Martelo, D.F.; Morana, Roberto; Akid, Robert

doi:10.1016/j.tafmec.2020.102871

Cited by 10 publications

(3 citation statements)

References 37 publications

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“…Therefore, to acquire great surface quality with minimal surface irregularities, the smallest RLT is anticipated. Therefore, the objective function of minimum SR was considered as per equation (7):…”

Section: Case A: Maximum Mrrmentioning

confidence: 99%

“…An austenitic structure in nickel-base super-alloys has an extended solubility for specific alloying additives and adequate characteristics to support the establishment of a particularly effective strengthening phase [6]. Ni-based super-alloys have ductility, higher cohesive energy, thermally induced creep, and a low diffusion coefficient [7]. Nickel-based super-alloys are identified as extremely difficult materials for machining to meet feature and manufacture requirements [8].…”

Section: Introductionmentioning

confidence: 99%

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Effect of Multi-walled carbon nanotubes on the performance evaluation of Nickel-based super-alloy–Udimet 720 machined using WEDM process

Chaudhari¹,

Ayesta

Doshi³

et al. 2022

Preprint

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The diverse capabilities of nickel-based super-alloy (Udimet 720), like robust mechanical strength, ductility, resistance to excessive temperature deformation, and advanced corrosion and oxidation resistance, make it suitable for use in multiple applications. These super-alloys are identified as extremely difficult materials for machining to meet feature and manufacturing requirements. In the present work, we demonstrated the machining of Udimet 720 by employing the wire-electrical discharge machining (WEDM) technique. Pulse-on-time (Ton), Pulse-off-time (Toff), current, and MWCNT amount were preferred as input variables. The effect of selected design variables was studied on material removal rate (MRR), surface roughness (SR), and recast layer thickness (RLT). Box Behnken design was utilized to design an experimental matrix. For statistical analysis, analysis of variance (ANOVA) was employed. From ANOVA, the current had the highest contributor with 35.85% to affect MRR, while MWCNT amount was found to be the highest contributor for deciding the values of both SR and RLT with contributions of 42.66% and 40.07%, respectively. The addition of MWCNT at 1 g/L has substantially improved MRR from 0.8546 g/min to 1.2199 g/min, SR reduced from 5.88 µm to 2.98 µm, and reduction in RLT from 17.8 µm to 11.61 µm. The passing vehicle search (PVS) algorithm was implemented, and the results of single-objective optimization presented the largest MRR of 1.8883 g/min, least SR of 1.89 µm, and least RLT of 9.70 µm. Additionally, a set of non-dominated solutions was obtained through Pareto optimal fronts. A small acceptable deviation was detected among the actual and forecasted results from PVS algorithm. It clearly reveals the acceptance of the PVS technique in the present study for Udimet 720. Lastly, the significance of MWCNT amount on surface textures was revealed by employing scanning electron microscopy (SEM).

show abstract

Section: Case A: Maximum Mrrmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Multi-walled carbon nanotubes on the performance evaluation of Nickel-based super-alloy–Udimet 720 machined using WEDM process

Chaudhari¹,

Ayesta

Doshi³

et al. 2022

Preprint

View full text Add to dashboard Cite

show abstract

“…The microstructure of the alloy is also known to strongly influence the susceptibility of the precipitation hardened alloys. In fact, it is suggested that the susceptibility of alloys 718 and 625 to HE increases with the volume fraction of precipitates in the matrix and at the grain boundaries [37], and that γ" phase has a detrimental effect on hydrogen embrittlement, whilst γ' has a beneficial effect [38].…”

Section: Introductionmentioning

confidence: 99%

Stress Corrosion Cracking of Additively Manufactured Alloy 625

et al. 2021

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Laser bed powder fusion (LPBF) is an additive manufacturing technology for the fabrication of semi-finished components directly from computer-aided design modelling, through melting and consolidation, layer upon layer, of a metallic powder, with a laser source. This manufacturing technique is particularly indicated for poor machinable alloys, such as Alloy 625. However, the unique microstructure generated could modify the resistance of the alloy to environment assisted cracking. The aim of this work was to analyze the stress corrosion cracking (SCC) and hydrogen embrittlement resistance behavior of Alloy 625 obtained by LPBF, both in as-built condition and after a standard heat treatment (grade 1). U-bend testing performed in boiling magnesium chloride at 155 and 170 °C confirmed the immunity of the alloy to SCC. However, slow strain rate tests in simulated ocean water on cathodically polarized specimens highlighted the possibility of the occurrence of hydrogen embrittlement in a specific range of strain rate and cathodic polarization. The very fine grain size and dislocation density of the thermally untreated specimens appeared to increase the hydrogen diffusion and embrittlement effect on pre-charged specimens that were deformed at the high strain rate. Conversely, heat treatment appeared to mitigate hydrogen embrittlement at high strain rates, however at the slow strain rate all the specimens showed a similar behavior.

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Effect of multi-walled carbon nanotubes on the performance evaluation of nickel-based super-alloy–Udimet 720 machined using WEDM process

Chaudhari

Ayesta

Doshi

et al. 2022

Int J Adv Manuf Technol

View full text Add to dashboard Cite

The diverse capabilities of nickel-based super-alloy (Udimet 720), like robust mechanical strength, ductility, resistance to excessive temperature deformation, and advanced corrosion and oxidation resistance, make it suitable for use in multiple applications. These super-alloys are identified as extremely difficult materials for machining to meet feature and manufacturing requirements. In the present work, we demonstrated the machining of Udimet 720 by employing the wire-electrical discharge machining (WEDM) technique. Pulse-on-time (Ton), pulse-off-time (Toff), current, and MWCNT amount were preferred as input variables. The effect of selected design variables was studied on material removal rate (MRR), surface roughness (SR), and recast layer thickness (RLT). Box-Behnken design was utilized to design an experimental matrix. For statistical analysis, analysis of variance (ANOVA) was employed. From ANOVA, the current had the highest contributor with 35.85% to affect MRR, while MWCNT amount was found to be the highest contributor for deciding the values of both SR and RLT with contributions of 42.66% and 40.07%, respectively. The addition of MWCNT at 1 g/L has substantially improved MRR from 0.8546 to 1.2199 g/min, SR reduced from 5.88 µm to 2.98 µm, and reduction in RLT from 17.8 to 11.61 µm. The passing vehicle search (PVS) algorithm was implemented, and the results of single-objective optimization presented the largest MRR of 1.8883 g/min, least SR of 1.89 µm, and least RLT of 9.70 µm. Additionally, a set of non-dominated solutions was obtained through Pareto optimal fronts. A small acceptable deviation was detected among the actual and forecasted results from PVS algorithm. It clearly reveals the acceptance of the PVS technique in the present study for Udimet 720. Lastly, the significance of MWCNT amount on surface textures was revealed by employing scanning electron microscopy (SEM).

show abstract

Understanding the mechanical behaviour of 718 and 625 + nickel based super-alloys under cathodic polarization

Cited by 10 publications

References 37 publications

Effect of Multi-walled carbon nanotubes on the performance evaluation of Nickel-based super-alloy–Udimet 720 machined using WEDM process

Effect of Multi-walled carbon nanotubes on the performance evaluation of Nickel-based super-alloy–Udimet 720 machined using WEDM process

Stress Corrosion Cracking of Additively Manufactured Alloy 625

Effect of multi-walled carbon nanotubes on the performance evaluation of nickel-based super-alloy–Udimet 720 machined using WEDM process

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