Suche
Anzeige der Dokumente 11-20 von 27
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
Innovative Materials for Novel Concepts for Internal Heat Exchangers
(2018-07-27)
Internal heat exchangers are often employed in solar thermal applications as well as in many other applications that involve heat, and, for the most part, consist of metallic materials (copper, stainless steel). Corrugated stainless steel tubes are easy to assemble, and are commonly used in various storage geometries. In order to significantly reduce costs, alternative materials, such as plastics, can function as excellent substitutes. Alternative heat exchangers for the following examinations using various materials ...
Aufsatz
The Manufacture of Hot-Compacted Layered Composite Systems Made of Oriented Semifinished PP-Films
(2014-03-04)
Monoaxial stretched PP-films are used for the manufacture of hot-compacted layered composites. These are layered with stretched co-extruded coupling agent films, and are consolidated to laminates by means of a hot-compaction process, which employs pressure and temperature. This paper aims to examine the influence of the process settings on the properties of the composites during the hot-compaction process. For this purpose, the mechanical values will be determined by means of tensile testing variously compacted and ...
Aufsatz
On the Effect of Quenching on Postweld Heat Treatment of Friction-Stir-Welded Aluminum 7075 Alloy
(2019)
This work focuses on the effect of postweld heat treatment (PWHT) on the mechanical properties and microstructural evolution of aluminum 7075 alloy processed via friction stir welding (FSW). FSW is known to be capable of grain refinement in the nugget zone (NZ). Two different quench media (water and air) were employed for PWHT. Regardless of the quench media, the PWHT led to the occurrence of grain growth in the NZ of the FSWed aluminum 7075 alloy. Abnormal grain growth occurred in the water quenched specimen. It is ...
Aufsatz
Effect of grain size on the very high cycle fatigue behavior and notch sensitivity of titanium
(2019)
The very high-cycle fatigue performances of coarse-grained and ultrafine-grained titanium samples with different geometries at ambient temperature and various stress amplitudes were investigated. Severe plastic deformation improves monotonic strength of titanium at the cost of a loss in ductility. Ultrafine-grained titanium demonstrates a superior fatigue performance compared to that of coarse-grained counterparts in the high-cycle fatigue regime, however, suffers notch sensitivity. Furthermore, in the very high-cycle ...
Aufsatz
Parameter identification for constitutive models of innovative textile composite materials using digital image correlation
(2019-11-18)
This contribution focuses on an innovative composite material consisting of textile layers made from continuous wooden fibers embedded in a thermoplastic matrix. A finite element simulation of potential use‐cases is planned to support the development process and to study the suitability of the material in an architectural context. The simulation is based on a constitutive model assuming homogenous orthotropic elastic behavior and will be expanded to include multiscale modeling in future research. The material parameters ...
Aufsatz
Energy Resolved Residual Stress Analysis with Laboratory X-Ray Sources
(2017-04-17)
It is well known that existing residual stress fields play an important role for strength and lifetime of components. Consequently there is a great interest in the availability of fast, reliable and possibly nondestructive methods for their determination. In this context, X-ray diffraction methods play an important role in technical practice as well as in scientific research. They are based on the determination of lattice strains from which residual stresses are determined applying Hooke's law with appropriate elastic ...
Aufsatz
Prozessintegration von induktiver Wärmebehandlung und Festwalzen – sichere und zuverlässige Komponenten mit hoher Schwingfestigkeit
(2017-02-08)
Mechanische Oberflächenbehandlungen, beispielsweise das Festwalzen, spielen in der technischen Praxis eine bedeutende Rolle und tragen wesentlich zur Steigerung der Zuverlässigkeit hochbeanspruchter Komponenten bei. In einer Reihe von Fällen wurde gezeigt, dass eine Erhöhung der Prozesstemperatur die Wirksamkeit der Verfahren noch steigert, weil dies zu einer besseren Stabilisierung der eingebrachten Druckeigenspannungen führt. Eine wesentliche Voraussetzung zur Einführung dieser Verfahren in die Praxis ist allerdings, ...
Aufsatz
Bend Straightening of a Carbonitrided Gear Shaft – Consequences on Residual Stresses and Retained Austenite near the Surface
(2017-06-20)
Carbonitriding of shafts in drive technology is strongly connected with distortion. Bend straightening is an important process step in order to eliminate distortion without removing the hardened surface layer. As shown in several investigations, even for simple part geometries, bending induced stresses and plastic deformations have a strong impact not only on the residual stress state but also on the microstructure after straightening. As gear shafts become increasingly filigree and complex in their geometry, the ...