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On the Monotonic and Cyclic Behavior of an Al-Mg-Zn-Cu-Si Compositionally Complex Alloy
(2023-08-03)
In present work, the monotonic and cyclic properties of a novel Al-Mg-Zn-Cu-Si compositionally complex alloy (CCA) are investigated. Microstructural studies reveal that a eutectic phase and fishbone-type structures are embedded in the Al-matrix. The mechanical properties of this CCA obtained under compressive loading are found to be promising. However, low ultimate strength and brittle behavior are seen under tension. The fatigue performance of the alloy in the low-cycle fatigue (LCF) regime is poor. Microstructural ...
Aufsatz
Hot Sheet Metal Forming Strategies for High-Strength Aluminum Alloys: A Review—Fundamentals and Applications
(2023-05-17)
In the past decade, aluminum alloys have become important structural materials in the automotive industry, thanks to their low density, high strength, high fracture toughness, and good fatigue performance. However, an important limitation of aluminum alloys is their poor formability at room temperature; as a result, numerous studies have been conducted with the aim of developing forming techniques to overcome this and facilitate the forming of more complex-shaped components. Following an overview on the metallurgical ...
Aufsatz
Experimental Analysis of the Stability of Retained Austenite in a Low-Alloy 42CrSi Steel after Different Quenching and Partitioning Heat Treatments
(2023-06-21)
Quenching and partitioning (Q&P) steels are characterized by an excellent combination of strength and ductility, opening up great potentials for advanced lightweight components. The Q&P treatment results in microstructures with a martensitic matrix being responsible for increased strength whereas interstitially enriched metastable retained austenite (RA) contributes to excellent ductility. Herein, a comprehensive experimental characterization of microstructure evolution and austenite stability is carried out on a ...
Aufsatz
Microstructural and mechanical properties of AlSi10Mg: Hybrid welding of additively manufactured and cast parts
(2022-12-07)
Welding and joining of hybrid components consisting of additively manufactured (AM) parts and conventionally processed parts offer new opportunities in structural design. In the present study, AlSi10Mg specimens were fabricated using two different manufacturing processes, i.e., laser-based powder-bed fusion of metals (PBF-LB/M) and casting, and welded by means of friction stir welding (FSW). Material strength of dissimilar welded joints was found to be governed by the as-cast material, which is characterized by a ...
Aufsatz
Additive Manufacturing of Binary Ni–Ti Shape Memory Alloys Using Electron Beam Powder Bed Fusion: Functional Reversibility Through Minor Alloy Modification and Carbide Formation
(2022-11-30)
Shape memory alloys (SMAs), such as Ni–Ti, are promising candidates for actuation and damping applications. Although processing of Ni–Ti bulk materials is challenging, well-established processing routes (i.e. casting, forging, wire drawing, laser cutting) enabled application in several niche applications, e.g. in the medical sector. Additive manufacturing, also referred to as 4D-printing in this case, is known to be highly interesting for the fabrication of SMAs in order to produce near-net-shaped actuators and ...
Aufsatz
Electron Beam Welding of Hot-Rolled Fe–Mn–Al–Ni Shape Memory Alloy Sheets
(2023-04-25)
The present study focuses on the weldability of hot-rolled Fe–Mn–Al–Ni shape memory alloy sheets by vacuum electron beam welding. Tailored process-specific welding parameters, such as preheating with electron beam or beam oscillation during welding, allowed defect-free joining with very thin weld seams and heat-affected zones. By applying a post-weld cyclic heat treatment, abnormal grain growth can be promoted across the weld seams. However, regardless of the selected welding parameters, some specimens are characterized ...
Aufsatz
Low-Cycle-Fatigue Performance of Stress-Aged EN AW-7075 Alloy
(2023-05-05)
The effect of a novel heat treatment, that is, aging under superimposed external stress, on the fatigue performance and microstructural evolution of a high-strength aluminum alloy (EN AW-7075) is presented. Stress aging, a combination of heat treatment and superimposed external stress, can enhance the mechanical properties of EN AW-7075 under monotonic loading due to the acceleration of precipitation kinetics. Scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM) reveal that a longer ...
Aufsatz
On the Reliability of Automated Analysis of Fracture Surfaces Using a Novel Computer Vision-Based Tool
(2023-08-05)
Fracture surface analysis is of utmost importance with respect to structural integrity of metallic materials. This especially holds true for additively manufactured materials. Despite an increasing trend of automatization of testing methods, the analysis and classification of fatigue fracture surface images is commonly done manually by experts. Although this leads to correct results in most cases, it has several disadvantages, e.g., the need of a huge knowledge base to interpret images correctly. In present work, an ...
Aufsatz
Cyclic Superelastic Behavior of Iron-Based Fe-Ni-Co-Al-Ti-Nb Shape Memory Alloy
(2023-01-03)
Iron-based shape memory alloys came into focus as promising candidate materials for large-scale structural applications owing to their cost-efficiency. In the present work, the superelastic properties of a recently introduced Fe-Ni-Co-Al-Ti-Nb shape memory alloy are investigated. For 〈001〉-oriented single-crystalline material in aged condition (650 °C/6 h), an incremental strain test reveals excellent superelasticity at −130 °C with fully reversible strains up to about 6%. Under cycling loading at different test ...
Aufsatz
Electrochemical polarization behavior and superelastic properties of a Fe–Mn–Al–Ni–Cr shape memory alloy
(2022-10-22)
The present study investigates the corrosion behavior of a Fe–Mn–Al–Ni–Cr shape memory alloy in a 5.0 wt% NaCl solution in combination with the functional properties. In a single crystalline condition, the investigated alloy shows a superior superelastic response with a maximum recovery strain of 5.2%. Furthermore, the results of the potentiodynamic polarization and impedance spectroscopy show that the addition of chromium generally improves corrosion resistance by increasing the resistance to localized corrosion. ...