Search
Now showing items 11-20 of 2006
Aufsatz
Effect of Tool Temperature on Mechanical Properties and Microstructure of Thermo-Mechanically Processed AA6082 and AA7075 Aluminum Alloys
(2020-06-08)
The present work focuses on the effect of thermo-mechanical processing on the mechanical properties and microstructural evolution of AA6082 and AA7075 aluminum alloys using a novel forming process, i. e. integrating solution heat treatment, hot forming and tool quenching. Different tool temperatures ranging from 24 °C to 350 °C were applied to investigate their influence on mechanical strength and ductility. By using various tool temperatures, this study aims to provide insights needed for tailoring the mechanical ...
Aufsatz
Plantain mycorrhization with native consortium of arbuscular mycorrhizal fungi (AMF) induce solubilisation of metals (Fe2+ and Al3+) in soil from Azaguié (south-east of Côte d’Ivoire)
(2023-04-28)
New agroecological practices propose to manage soil fertility using soil microorganisms such as arbuscular mycorrhizal fungi (AMF). However, few studies have been conducted on the impact of plantain mycorrhization and metal (Fe²+ and Al³+) solubilisation in soil. This study evaluates the effectiveness of native AMF on plantain growth and metal leaching from soil. Trap plants (maize, sorghum and cowpea) were grown to produce various inoculums. Then, plantains were grown under controlled conditions, with six treatments ...
Aufsatz
Predicting Flow Stress Behavior of an AA7075 Alloy Using Machine Learning Methods
(2022-09-09)
The present work focuses on the prediction of the hot deformation behavior of thermo-mechanically processed precipitation hardenable aluminum alloy AA7075. The data considered focus on a novel hot forming process at different tool temperatures ranging from 24°C to 350°C to set different cooling rates after solution heat-treatment. Isothermal uniaxial tensile tests in the temperature range of 200°C to 400°C and at strain rates ranging from 0.001 s-¹ to 0.1 s-¹ were carried out on four different material conditions. ...
Aufsatz
Effects of Aging under Stress on Mechanical Properties and Microstructure of EN AW 7075 Alloy
(2021-07-20)
In the present study, microstructural and mechanical properties of EN AW 7075 following stress-aging were assessed. For this purpose, properties of stress-aged samples were compared with values obtained for conventionally aged counterparts. It is revealed that the strength and hardness of EN AW 7075 can be increased by the presence of external stresses during aging. Precipitation kinetics were found to be accelerated. The effects of conventional and stress-aging on the microstructure were analyzed using synergetic ...
Aufsatz
Effect of Friction Stir Processing on Microstructural, Mechanical, and Corrosion Properties of Al-Si12 Additive Manufactured Components
(2020-01-03)
Additive manufacturing (AM) is an advanced manufacturing process that provides the opportunity to build geometrically complex and highly individualized lightweight structures. Despite its many advantages, additively manufactured components suffer from poor surface quality. To
locally improve the surface quality and homogenize the microstructure, friction stir processing (FSP) technique was applied on Al-Si12 components produced by selective laser melting (SLM) using two different working media. The effect of FSP on ...
Aufsatz
Influence of complex geometries on the properties of laser-hardened surfaces
(2020-04-25)
Laser surface hardening provides for many advantages in terms of flexible production due to very localized and controlled energy input into the material. Laser processing offers the possibility to treat surfaces in order to locally strengthen the areas that are prone to fatigue cracking. It is well known that laser energy absorption depends on many parameters, e.g., the surface structure and the surface orientation. The incident angle of the laser beam plays a key role in this regard. When complex geometries like ...
Aufsatz
Effect of Post-Process Machining on Surface Properties of Additively Manufactured H13 Tool Steel
(2018-08-28)
Der Werkzeugstahl AISI H13 zeichnet sich durch einen hohen Verschleißwiderstand und eine gute Temperaturwechselbeständigkeit aus. Hauptanwendungsbereiche des H13 sind Druckguss- und Schmiedewerkzeuge. Die Verarbeitung von H13 durch additive Fertigungsverfahren, wie z. B. dem selektiven Laserschmelzen (selective laser melting, SLM), eröffnet neue Gestaltungsmöglichkeiten, wie z. B. die Integration interner Kühlkanäle, die es erlauben, das Einsatzverhalten der Werkzeuge zu verbessern. Aufgrund hoher Oberflächenrauheiten ...
Aufsatz
A Screening Approach for Rapid Qualitative Evaluation of Residual-Stress States – Application to Laser-Hardened Microalloyed Steel
(2019-06-11)
Surface hardening and compressive residual stresses are keys to superior part performance in numerous applications. In this context the development of advanced laser surface treatments for new materials and complex sample shapes is a time con-suming process. Eventually, determination of residual stress states by means of X-ray diffraction in the whole surface and subsurface region, respectively, is one of the main time consuming facors in terms of characterization. In many applications the provision of an adequate ...
Aufsatz
Consequences of Deep Rolling at Elevated Temperature on Near-Surface and Fatigue Properties of High-Manganese TWIP Steel X40MnCrAl19-2
(2021-11-05)
Due to pronounced work-hardening induced by the complex interplay of deformation mechanisms such as dislocation slip, twinning and/or martensitic phase transformation, high-manganese steels represent a class of materials well-suited for mechanical surface treatment. In the present study, the fatigue behavior of a high-mangsanese steel showing twinning-induced plasticity (TWIP) effect at room temperature (RT) was investigated after deep rolling at 550 °C. Results are compared to a former study discussing the behavior ...
Aufsatz
Supervision: Kunst oder Wissenschaft?
(2001)
In der Betrachtung der Supervision begegnen sich zwei unterschiedliche Perspektiven. Einerseits wird Supervision als schlichte Anwendung wissenschaftlich gewonnener Erkenntnisse gewertet. Andererseits lässt sie sich jedoch auch als eine "Kunst" begreifen. Die Autoren gehen davon aus, dass sich professionelles supervisorisches Handeln nicht hierarchisch einem wissenschaftlichen Regelwerk unterstellen lässt, sondern dass beide Bereiche gleichberechtigt ihren je eigenen Diskurs- und Handlungsformen folgen. Sinnvoll ...