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Liquid Silicone Rubber Foams Made with Water as Blowing Agent
(2021-08-18)
Liquid silicone rubber (LSR) is primarily used in injection molding. Foamed molded parts made of LSR are almost nonexistent because the process reliability of LSR foam injection molding is currently not given. It makes sense to have suitable foaming processes for this material as well, because the density of this elastomer is about 1.15 g cm−3. With the injection molding process presented herein for foaming LSR, density reductions of up to 40% can be achieved. In this process, up to 3% by weight of water is added to ...
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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 ...
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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 ...
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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 ...
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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 ...
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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. ...
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Hot Work Tool Steel Processed by Laser Powder Bed Fusion: A Review on Most Relevant Influencing Factors
(2021-03-26)
As a representative of a common carbon-bearing hot work tool steel AISI H13 is in focus of the present review paper. Most relevant details for processing of AISI H13 by laser powder bed fusion (L-PBF) are systematically investigated. Three common stages of process parameter development and material assessment, respectively, are in focus: general processibility, process refinement, and deduction of process–microstructure–property relations, i.e., understanding of the interplay of relevant elementary mechanisms. On the ...
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CuCrZr processed by laser powder bed fusion — Processability and influence of heat treatment on electrical conductivity, microstructure and mechanical properties
(2021-06-16)
CuCrZr parts were fabricated by laser beam powder bed fusion (LB-PBF) technique and subjected to different heat treatments. As a result, four different conditions were considered for further investigations, that is, the as-built condition, conditions of maximum hardness (MH) and maximum electrical conductivity (MC), and a condition representing a compromise between hardness and conductivity (H&C). Microstructural evolution and performance under monotonic and cyclic loading were studied. Fracture surfaces revealed ...
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On the Microstructural and Cyclic Mechanical Properties of Pure Iron Processed by Electron Beam Melting
(2021-03-10)
Additive manufacturing (AM) processes such as electron beam melting (EBM) are characterized by unprecedented design freedom. Topology optimization and design of the microstructure of metallic materials are enabled by rapid progress in this field. The latter is of highest importance as many applications demand appropriate mechanical as well as functional material properties. For instance, biodegradable implants have to meet mechanical properties of human bone and at the same time guarantee adequate cytocompatibility ...
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Thermal Stability of Residual Stresses in Differently Deep Rolled Surface Layers of Steel SAE 1045
(2021-05-07)
The stability of compressive residual stresses generated by deep rolling plays a decisive role on the fatigue behavior of specimens and components, respectively. In this regard, deep rolling at elevated temperature has proven to be very effective in stabilizing residual stresses when fatigue analysis is conducted at ambient temperature. However, since residual stresses can be affected not only by plastic deformation but also when thermal energy is provided, it is necessary to analyze the influence of temperature and ...