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32 pages, 27453 KiB

Open AccessArticle

The Effects of Layer Thickness on the Mechanical Properties of Additive Friction Stir Deposition-Fabricated Aluminum Alloy 6061 Parts

by Hamed Ghadimi, Mojtaba Talachian, Huan Ding, Selami Emanet and Shengmin Guo

Metals 2024, 14(1), 101; https://doi.org/10.3390/met14010101 - 14 Jan 2024

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Abstract

Solid-state additive friction stir deposition (AFSD) is a thermomechanical-based additive manufacturing technique. For this study, AFSD was utilized to produce aluminum alloy 6061 (AA6061) blocks with varying layer thicknesses (1 mm, 2 mm, and 3 mm). The mechanical properties were assessed through uniaxial [...] Read more.

Solid-state additive friction stir deposition (AFSD) is a thermomechanical-based additive manufacturing technique. For this study, AFSD was utilized to produce aluminum alloy 6061 (AA6061) blocks with varying layer thicknesses (1 mm, 2 mm, and 3 mm). The mechanical properties were assessed through uniaxial tensile tests and Vickers microhardness measurement, and statistical analysis was employed to investigate differences among data groups. The results revealed that the deposition layer thickness influences tensile properties in the building (Z) direction, while the properties in the X and Y directions showed minor differences across the three AFSD blocks. Furthermore, variations in tensile properties were observed depending on the sample orientation in the AFSD blocks and its depth-wise position in the part in the building direction. The microhardness values decreased non-linearly along the building direction, spread across the width of the part’s cross-section, and highlighted that the deposition layer thickness significantly affects this property. The 1 mm block exhibited lower average microhardness values than the 2 mm and 3 mm blocks. The temperature histories and dynamic heat treatment are influenced by the deposition layer thickness and depend on the location of the point being studied in the part, resulting in variations in the microstructure and mechanical properties along the building direction and across the part’s width. Full article

(This article belongs to the Special Issue Microstructure and Properties of Metallic Materials Produced by Additive Manufacturing)

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14 pages, 22422 KiB

Open AccessArticle

Analysis of Face-Centered Cubic Phase in Additively Manufactured Commercially Pure Ti

by Claire L. Adams and David P. Field

Metals 2023, 13(12), 2005; https://doi.org/10.3390/met13122005 - 13 Dec 2023

Viewed by 1021

Abstract

Metal additive manufacturing is a developing technique with numerous advantages and challenges to overcome. As with all manufacturing techniques, the specific raw materials and processing parameters used have a profound influence on microstructures and the resulting behavior of materials. It is important to [...] Read more.

Metal additive manufacturing is a developing technique with numerous advantages and challenges to overcome. As with all manufacturing techniques, the specific raw materials and processing parameters used have a profound influence on microstructures and the resulting behavior of materials. It is important to understand the relationship between processing and microstructures of Ti to advance knowledge of Ti-alloys in the additive field. In this study, a face-centered cubic (FCC) phase was found in grade 2 commercially pure titanium specimens, additively manufactured with directed energy deposition in an argon atmosphere. Two scanning speeds (500 and 1000 mm/min) and three scanning patterns (cross-hatched and unidirectional patterns) were investigated. Electron backscatter diffraction and energy-dispersive X-ray spectroscopy were used for microstructural and compositional analysis. Inverse pole figure, phase, and kernel average misorientation (KAM) maps were analyzed in this work. Larger amounts of the FCC phase were found in the unidirectional scanning patterns for the slower scanning speed, while the cross-hatched pattern for both scanning speeds showed a lower amount of FCC. Higher KAM averages were present in the faster scanning speed specimens. According to EDS scans, small amounts of nitrogen were uniformly distributed throughout the specimens, leading to the possibility of interstitial content as a contributing factor for development of the observed FCC phase. However, there is no clear relationship between nitrogen and the FCC phase. The formation of this FCC phase could be connected to high densities of crystalline defects from processing, plastic deformation, or the distribution of interstitials in the AM structure. An unexpected Kurdjumow–Sachs-type orientation relationship between the parent beta phase and FCC phase was found, as

{\{110\}}_{B C C} ∥ {\{111\}}_{F C C}

,

{⟨111⟩}_{B C C} ∥ {⟨110⟩}_{F C C}

. Full article

(This article belongs to the Special Issue Microstructure and Properties of Metallic Materials Produced by Additive Manufacturing)

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16 pages, 3254 KiB

Open AccessArticle

Ratcheting–Fatigue Damage Assessment of Additively Manufactured SS304L and AlSi10Mg Samples under Asymmetric Stress Cycles

by M. Servatan, S. M. Hashemi and A. Varvani-Farahani

Metals 2023, 13(9), 1534; https://doi.org/10.3390/met13091534 - 30 Aug 2023

Cited by 1 | Viewed by 920

Abstract

The present study aims to investigate the interaction of ratcheting and fatigue phenomena for additively manufactured (AM) samples of SS304L and AlSi10Mg undergoing uniaxial asymmetric stress cycles. Overall damage was accumulated through fatigue and ratcheting on AM samples prepared from three-dimensional-printed plates along [...] Read more.

The present study aims to investigate the interaction of ratcheting and fatigue phenomena for additively manufactured (AM) samples of SS304L and AlSi10Mg undergoing uniaxial asymmetric stress cycles. Overall damage was accumulated through fatigue and ratcheting on AM samples prepared from three-dimensional-printed plates along vertical and horizontal directions. Fatigue damage was evaluated based on the strain energy density fatigue approach and ratcheting damage was calculated through use of an isotropic–kinematic hardening framework. The isotropic description through the Lee–Zavrel (L–Z) model formed the initial and concentric expansion of yield surfaces while the Ahmadzadeh–Varvani (A–V) kinematic hardening rule translated yield surfaces into the deviatoric stress space. Ratcheting of AM samples was simulated using finite element analysis through use of triangular and quadrilateral elements. Ratcheting values of the AM samples were simulated on the basis of Chaboche’s materials model. The predicted and simulated ratcheting damage curves placed above the experimental fatigue–ratcheting experimental data while predicted fatigue damage curves collapsed below the measured values. The overall damage was formulated to partition damage weights due to fatigue and ratcheting phenomena. Full article

(This article belongs to the Special Issue Microstructure and Properties of Metallic Materials Produced by Additive Manufacturing)

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