Porosity in wire arc additive manufacturing of aluminium alloys

Hauser, Tobias; Reisch, Raven T.; Breese, Philipp P.; Lutz, Benjamin; Pantano, Matteo; Nalam, Yogesh; Bela, Katharina; Kamps, Tobias; Volpp, Jöerg; Kaplan, Alexander

doi:10.1016/j.addma.2021.101993

Cited by 55 publications

(36 citation statements)

References 24 publications

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“…In terms of printing defects, Figure 5 clearly demonstrates the presence of macroporosity and microporosity with sizes of 1 µm and up to 6 µm, respectively, in both the XY and XZ planes. This porosity can be identified as “keyholing porosity” or intralayer porosity, usually generated due to the use of an inert protective gas atmosphere and consequent gas entrapment [ 32 ], as can be expected from DED processes [ 41 , 42 , 43 ]. It should be pointed out that such porosity can have a significant detrimental effect on the mechanical properties and, in particular, on the fatigue endurance due to the fact that pores can act as fatigue initiation sites.…”

Section: Resultsmentioning

confidence: 99%

The Influence of Intralayer Porosity and Phase Transition on Corrosion Fatigue of Additively Manufactured 316L Stainless Steel Obtained by Direct Energy Deposition Process

et al. 2022

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A direct energy deposition (DED) process using wires is considered an additive manufacturing technology that can produce large components at an affordable cost. However, the high deposition rate of the DED process is usually accompanied by poor surface quality and inherent printing defects. These imperfections can have a detrimental effect on fatigue endurance and corrosion fatigue resistance. The aim of this study was to evaluate the critical effect of phase transition and printing defects on the corrosion fatigue behavior of 316L stainless steel produced by a wire laser additive manufacturing (WLAM) process. For comparison, a standard AISI 316L stainless steel with a regular austenitic microstructure was studied as a counterpart alloy. The structural assessment of printing defects was performed using a three-dimensional non-destructive method in the form of X-ray microtomography (CT) analysis. The microstructure was evaluated by optical and scanning electron microscopy, while general electrochemical characteristics and corrosion performance were assessed by cyclic potentiodynamic polarization (CCP) analysis and immersion tests. The fatigue endurance in air and in a simulated corrosive environment was examined using a rotating fatigue setup. The obtained results clearly demonstrate the inferior corrosion fatigue endurance of the 316L alloy produced by the WLAM process compared to its AISI counterpart alloy. This was mainly related to the drawbacks of WLAM alloys in terms of having a duplex microstructure (austenitic matrix and secondary delta-ferrite phase), reduced passivity, and a significantly increased amount of intralayer porosity that acts as a stress intensifier of fatigue cracking.

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Section: Resultsmentioning

confidence: 99%

The Influence of Intralayer Porosity and Phase Transition on Corrosion Fatigue of Additively Manufactured 316L Stainless Steel Obtained by Direct Energy Deposition Process

et al. 2022

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“…The strong influence of weld quality in terms of porosity and cracks on the pin's shear resistance attests the need for an optimized welding process as well as wire feedstock. Overall weld quality depends on a multitude of factors but for porosity the main contributors are suitable process parameters and usage of high-quality welding wire [20,22,23,[32][33][34]. The adaption of process parameters is limited by the restricted processing window for pin fabrication further amplifying the necessity of high-quality welding wires.…”

Section: Discussionmentioning

confidence: 99%

Mechanical and microstructural characterization of aluminium micro-pins realized by cold metal transfer

Schneider-Bröskamp¹,

Schnall²,

Birgmann³

et al. 2022

Preprint

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Advanced and reliable joining technologies for ultra-light weight structures combining aluminium with carbon fibre reinforced plastics (CFRP) are of great interest for aerospace industries. The combination of superior mechanical properties and low density offer a wide range of possible application. The European collaborative research project ADALFIC (Advanced Aluminium Fittings in CFRP tubes) focuses on the design, analysis, manufacturing and testing of ultra-lightweight CFRP tubes with integrated aluminium end fittings. These aluminium end fittings are equipped with very small, minimum-mass, spike-head pins realized by Fronius' cold-metal-transfer (CMT) Print welding technology. These pins are optimized for form-locked joints between aluminium and CFRP components. In this work the aluminium pins are characterized on a macroscopic and microscopic level using light optical microscopy and hardness testing. To evaluate the behavior of the pins under mode II load conditions a new shear testing method for pins was developed and implemented. With this test equipment the maximum shear force and ultimate shear strength of individual pins was measured at different temperatures and heat treatment conditions. The failure modes and fracture surfaces were analyzed via scanning electron microscopy. The results demonstrate that CMT aluminium pins are a viable, flexible and lightweight option for form-locked aluminium-CFRP joints.

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“…Existence of Porosity is one of crucial troubles in WAAM process, which can reduce the overall density of the produced parts and thus severely harm the mechanical properties of the fabricated components [59,86,87]. Pores can be mainly sorted into small and homogenously distributed hydrogen pores, with a diameter size up to 100 µm, and into big and in homogeneously distributed process pores [87]. Porosity is generated by various reasons including type of the used arc welding process, process parameters, inter pass temperature, wire alloy composition and quality [59].…”

Section: Poresmentioning

confidence: 99%

“…PN Anyalebechi [88], explained that gas porosity is usually caused by two concomitant mechanisms, namely, volumetric shrinkage and the change in the solubility and associated precipitation of hydrogen during solidification. Process related pores are distributed more inhomogeneously in aluminum and can be triggered by entrapment of shielding gas, air (oxygen and nitrogen), or other gases which cannot escape because of the rapid material solidification [87]. Fu Rui et al [89] stated that Hydrogen is believed to be the main cause of the porosity in WAAM aluminum alloys.…”

Section: Poresmentioning

confidence: 99%

A Brief Review on The Common Defects in Wire Arc Additive Manufacturing

Albannai¹

2022

ijcsrr

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Wire arc additive manufacturing (WAAM) process, which depends on conventional welding arc processes, is a promising option for industries when compared to typical manufacturing processes for assembling large and complicated products. WAAM process attracting manufacturing industries due to its potential to make large and complicated components with real sharp production run time with almost single step process. The process represents greater material savings, higher material buildup rate and speed, cost savings, lower cycle time, less impact on the environment, and capability of producing large size parts when evaluated with other fabrication methods. This paper focuses on WAAM process and reviews some of the common possible process defects found in variety of studies made previously to summaries a guideline for the causes of such defects and provides some prevention methods found by those studies. Of these common possible defects found in researchers works and reviewed in this work are pores, lack of fusion, cracks, and residual stress.

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Porosity in wire arc additive manufacturing of aluminium alloys

Cited by 55 publications

References 24 publications

The Influence of Intralayer Porosity and Phase Transition on Corrosion Fatigue of Additively Manufactured 316L Stainless Steel Obtained by Direct Energy Deposition Process

The Influence of Intralayer Porosity and Phase Transition on Corrosion Fatigue of Additively Manufactured 316L Stainless Steel Obtained by Direct Energy Deposition Process

Mechanical and microstructural characterization of aluminium micro-pins realized by cold metal transfer

A Brief Review on The Common Defects in Wire Arc Additive Manufacturing

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