Control of macro-/microstructure and mechanical properties of a wire-arc additive manufactured aluminum alloy

Klein, Thomas; Schnall, Martin

doi:10.1007/s00170-020-05396-6

Cited by 48 publications

(11 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…LDM, WAAM) are also suitable for the production of AM components. Numerous metallic materials can be used, such as steels [2][3][4], aluminium materials [5][6][7] and nickel-based alloys [8][9][10]. Titanium and its alloys are of particular interest, especially to the aerospace industry, due to their excellent properties, including their high strength to density ratio and their resistance to corrosive environments [11].…”

Section: Introductionmentioning

confidence: 99%

Contactless temperature measurement in wire-based electron beam additive manufacturing Ti-6Al-4V

et al. 2021

View full text Add to dashboard Cite

The complex thermal cycles and temperature distributions observed in additive manufacturing (AM) are of particular interest as these define the microstructure and the associated properties of the part being built. Due to the intrinsic, layer-by-layer material stacking performed, contact methods to measure temperature are not suitable, and contactless methods need to be considered. Contactless infrared irradiation techniques were applied by carrying out thermal imaging and point measurement methods using pyrometers to determine the spatial and temporal temperature distribution in wire-based electron beam AM. Due to the vacuum, additional challenges such as element evaporation must be overcome and additional shielding measures were taken to avoid interference with the contactless techniques. The emissivities were calibrated by thermocouple readings and geometric boundary conditions. Thermal cycles and temperature profiles were recorded during deposition; the temperature gradients are described and the associated temperature transients are derived. In the temperature range of the α+β field, the cooling rates fall within the range of 180 to 350 °C/s, and the microstructural characterisation indicates an associated expected transformation of β→α'+α with corresponding cooling rates. Fine acicular α and α’ formed and local misorientation was observed within α as a result of the temperature gradient and the formation of the α’.

show abstract

Section: Introductionmentioning

confidence: 99%

Contactless temperature measurement in wire-based electron beam additive manufacturing Ti-6Al-4V

et al. 2021

View full text Add to dashboard Cite

show abstract

“…As also discussed by Zhang et al (2018), the CMT advanced process tends to lead to a finer grain size than the DCEP mode, as there is a dendrite fragmentation process promoted by a stronger stirring effect in the molten pool in first case, which is related to its periodic polarity inversion. However, also for the CMT advanced process, Zhang et al (2020) and Klein and Schnall (2020) observed that the grain size was coarser as the time in the positive semi-cycle was increased. In this circumstance, their studies suggest that this behavior results from the higher heat input attributed to the longer time spent in the positive polarity, i.e.…”

Section: Macro and Microstructural Characterizationmentioning

confidence: 94%

“…It is important to notice that a total of twenty short-circuits for the full cycle is kept. It is worth mentioning that another possible approach, not explored in the present work, would be the variation of the number of short-circuits in a full cycle while maintaining the same ratio between the EP and EN semi-cycles, as demonstrated by Klein and Schnall (2020) and Hwang et al (2020).…”

Section: Cold Metal Transfer Advanced Process Working Featuresmentioning

confidence: 99%

Effect of the CMT advanced process combined with an active cooling technique on macro and microstructural aspects of aluminum WAAM

Teixeira

Scotti

Reis

et al. 2021

RPJ

View full text Add to dashboard Cite

Purpose This paper aims to assess the combined effect of the Cold Metal Transfer (CMT) advanced process and of a thermal management technique (near immersion active cooling [NIAC]) on the macro and microstructure of Al wall-like preforms built by wire arc additive manufacturing (WAAM). As specific objective, it sought to provide information on the effects of the electrode-positive/electrode-negative (EP/EN) parameter in the CMT advanced process fundamental characteristics. Design/methodology/approach Initially, bead-on-plate deposits were produced with different EP/EN ratios, still keeping the same deposition rate, and the outcomes on the electrical signal traces and bead formation were analyzed. In a second stage, the EP/EN parameter and the layer edge to water distance (LEWD) parameter from the NIAC technique were systematically varied and the resultant macro and microstructures compared with those formed by applying natural cooling. Findings Constraints of EP/EN setting range were uncovered and discussed. The use of the NIAC technique favors the formation of finer grains. For a given EP/EN value, a variation in the NIAC intensity (LEWD value) showed marginal effect on grain size. When the EP/EN parameter effect is isolated, i.e. for a given LEWD setting, it was observed that an increase in the EP/EN level favors coarser grains. Originality/value Both the EP/EN parameter and the use of an active cooling technique (NIAC) might be used, even in combination, as effective tools for achieving proper macro and microstructure in WAAM of thin wall builds.

show abstract

“…This setup combines two CMT-systems. Recent works provided evidence for the suitability of CMT for WAAM of various aluminium alloys [8,[14][15][16]. The two torches (ML-AlSi7Mg and ML-AlSi12) were used with mean welding currents of 51 A and 65 A and mean voltages of 11.7 V and 15.9 V, respectively.…”

Section: Processingmentioning

confidence: 99%

“…The resulting droplet is deposited by a robotic or portal system according to a predefined track cumulatively resulting in the build-up of whole components or the modification of semifinished products [4]. The iterative droplet deposition sequence results in an accumulation of heat -an intrinsic process characteristic -determining the alloy dependent microstructure formation sequence [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

In situ alloying of aluminium-based alloys by (multi-)wire-arc additive manufacturing

2020

Self Cite

View full text Add to dashboard Cite

Wire-arc additive manufacturing (WAAM) has received considerable attention in the past years due to advantages in terms of deposition rate, design freedom, buy-to-fly ratio and economic factors. This process can generally be conducted using conventional or near-conventional welding equipment to fabricate intricate but relatively large-scale structures. The present contribution explores options to utilize this novel process not only for manufacturing of particular aluminium structures, but to create the actual alloy composition during processing. Thereby, the possibilities of dual-wire techniques based on cold metal transfer (CMT) to create alloys in the welding process in situ is investigated. For this purpose, a modified CMT twin welding system is used with standard wires differing significantly in their alloying content. The characterization of the chemical compositions at different specimen positions suggests good chemical homogeneity after initial process optimization steps. The microstructural homogeneity is analysed by means of optical light microscopy and scanning electron microscopy. Quantified phase fractions underpin non-equilibrium solidification conditions, when compared to theoretical equilibrium predictions. The assessment of the performed analyses suggests that dual-wire processes are powerful in terms of enhancing achievable depositions rates as well as enabling in situ alloying. This approach might be expandable to multi-wire-based techniques.

show abstract

Control of macro-/microstructure and mechanical properties of a wire-arc additive manufactured aluminum alloy

Cited by 48 publications

References 43 publications

Contactless temperature measurement in wire-based electron beam additive manufacturing Ti-6Al-4V

Contactless temperature measurement in wire-based electron beam additive manufacturing Ti-6Al-4V

Effect of the CMT advanced process combined with an active cooling technique on macro and microstructural aspects of aluminum WAAM

In situ alloying of aluminium-based alloys by (multi-)wire-arc additive manufacturing

Contact Info

Product

Resources

About