Search
Now showing items 151-160 of 1223
Aufsatz
Data‑driven prediction of the surface layer state in hard‑turning for optimization of component quality
(2024-01-30)
Data-driven approaches are an effective solution for modeling problems in machining. To increase the service life of hardturned components, it is important to quantify the correlation between the cutting parameters such as feed rate, cutting speed and depth of cut and the near-surface properties. For obtaining high-quality models with small data sets, different data-driven approaches are investigated in this contribution. Additionally, models that enable uncertainty quantification are crucial for effective decision-making ...
Aufsatz
Gradual Coordination and Reversible P–P Bond Activation of a P3-Unit with Transition Metal Carbony
(2024-03-20)
Coordination of a stereochemically defined P3-chain to a series of transition metal carbonyls [M(CO)x]z− (M = Mn (x = 5, z = 1), Fe (x = 4, z = 2) or Co (x = 4, z = 1)) is explored using a 3]ferrocenophane scaffold. A gradual transition from 𝜼1-, 𝜼2- to 𝜼3-coordination is observed where in the 𝜼2-mode the terminal positions of the phosphorus chain are bridged. With an excess of cobalt carbonyl successive P–P bond activation and gradual separation of the central phosphorus atoms from the phosphorus chain has been ...
Aufsatz
Nitrogen fixation of lablab and finger millet in South-India
(2023-12-21)
Background
In a long-term rotation experiment (2016–2022) with different nitrogen (N) fertilizer levels in subtropical South-India, crop yields of low N plots were unexpectedly high. We therefore hypothesized that in the absence of mineral N application, these yields are largely due to N inputs by N₂ fixation in the component crops. To assess the diazotrophic N₂-fixation of lablab (Lablab purpureus L. Sweet) and possible associative N₂-fixation of finger millet (Eleusine coracana L. Gaertn), a controlled experiment ...
Aufsatz
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 ...