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Wire arc additive manufacturing (WAAM) presents a highly promising alternative to conventional subtractive manufacturing methods to produce metallic components, particularly in the aerospace industry, where there is a demand for 17–4 precipitation-hardened (PH) stainless steel structures. This study focuses on investigating the microstructural characteristics, showing microhardness evaluations, and analyzing the tensile properties of the as-printed parts during the 17–4 PH manufacturing process at different locations and directions. The fabrication is carried out using gas metal wire arc additive manufacturing (GM-WAAM). As a result, it was found that the microstructure of the as-deposited part showed a complex configuration consisting of both finely equiaxed and coarsely formed δ-ferrite phases with vermicular and lathy morphologies. These phases were dispersed inside the martensitic matrix, while a small amount of retained austenite was also present. It was observed that the volume fraction of retained austenite (20–5%) and δ-ferrite phases (15.5–2.5%) decreased gradually from the bottom to the top of the as-deposited wall. This reduction in the fractions of these phases resulted in a progressive increase in both hardness (∼37%) and ultimate tensile strength (UTS) along the building direction. This study successfully fabricates a high-strength and ductile 17–4 PH as-printed part using WAAM. The findings provide evidence supporting the feasibility of employing WAAM for producing defect-free, high-strength components on a large scale while maintaining mechanical properties similar or better than wrought alloy 17–4 PH.
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Integrating robotic wire arc additive manufacturing and machining: hybrid WAAM machining
Wire arc additive manufacturing (WAAM) has received increasing use in 3D printing because of its high deposition rates suitable for components with large and complex geometries. However, the lower forming accuracy of WAAM than other metal additive manufacturing methods has imposed limitations on manufacturing components with high precision. To resolve this issue, we herein implemented the hybrid manufacturing (HM) technique, which integrated WAAM and subtractive manufacturing (via a milling process), to attain high forming accuracy while taking advantage of both WAAM and the milling process. We describe in this paper the design of a robot-based HM platform in which the WAAM and CNC milling are integrated using two robotic arms: one for WAAM and the other for milling immediately following WAAM. The HM was demonstrated with a thin-walled aluminum 5356 component, which was inspected by X-ray micro-computed tomography (μCT) for porosity visualization. The temperature and cutting forces in the component under milling were acquired for analysis. The surface roughness of the aluminum component was measured to assess the surface quality. In addition, tensile specimens were cut from the components using wire electrical discharge machining (WEDM) for mechanical testing. Both machining quality and mechanical properties were found satisfactory; thus the robot-based HM platform was shown to be suitable for manufacturing high-quality aluminum parts.
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- Award ID(s):
- 2219347
- PAR ID:
- 10472065
- Editor(s):
- Andrew Yeh-Ching Nee, editor-ion-chief
- Publisher / Repository:
- Springer
- Date Published:
- Journal Name:
- The International Journal of Advanced Manufacturing Technology
- ISSN:
- 0268-3768
- Subject(s) / Keyword(s):
- Hybrid manufacturing WAAM Machining Robots
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Wire arc additive manufacturing (WAAM) is an effective technique for producing medium to large-size components, due to its convenience and sustainability in fabricating large-scale parts with high deposition rates, employing low-cost and simple equipment, and attaining high material efficiency. Thus, WAAM attracts different industrial sectors and has experienced great growth, particularly over the last decade to overcome production market’s challenges. Consequently, fabricating parts in WAAM, mostly resulted in heterogeneity in microstructure of three different zones towards the buildup direction due to different cooling rates; upper zone (thin surface layer of fine grains), middle zone (undesired large columnar grains covers 90% of the produced part), and lower zone (intermediate columnar grains close to substrate material). Accordingly, producing parts consisting of different zones affects the final component's mechanical properties. Therefore, controlling the formation of these zones is a key role in improving WAAM technique. Altering torch motion and cooling rates were found to be effective methods to control the homogeneity of the final component in WAAM.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1007/s00170-023-12517-4
