Volume 54, Issue 10

Kurzfassung Die Kurbelwelle unterliegt im Betrieb einer komplexen Beanspruchung. Gerade die Übergangsradien der Lagerzapfen zu den Kurbelwangen sowie die Austritte der Ölbohrungen zur Schmierung der Haupt- und Hublagerzapfen stellen schwingbruchgefährdete Stellen dar, welche durch kostenintensive Fertigungs- und Oberflächenverfestigungsprozesse optimiert werden. Um die Untersuchung der Wirksamkeit dieser Maßnahmen in einer Betriebsfestigkeitsprüfung unter möglichst realitätsnaher Beanspruchung zu ermöglichen, wurde bei IABG mbH ein neues Kurbelwellenprüfkonzept entwickelt, welches im folgenden Beitrag vorgestellt und im Vergleich mit gängigen Kurbelwellenprüfverfahren diskutiert wird. Dieses Prüfverfahren ist gleichsam für Kurbelwellen von Reihen- als auch V-Motoren geeignet.

Kurzfassung Im Auslegungsprozess von Zylinderköpfen spielt die Bewertung der thermomechanischen Ermüdung eine wesentliche Rolle. Der IABG- Zylinderkopfprüfstand basiert auf einer innovativen Methode, die eine Beurteilung und Optimierung von Zylinderköpfen hinsichtlich thermomechanischer Ermüdung bereits in einem sehr frühen Entwicklungsstadium erlaubt. Durch die im Vergleich zu konventionellen Prüfmethoden deutlich kürzeren Versuchszeiten bietet der Prüfstand die Möglichkeit, die Entwicklungszeiten neuer Zylinderkopfkonzepte bei gleichzeitiger Reduzierung der Versuchskosten erheblich zu verkürzen. Der offene Aufbau des Prüfstandes ermöglicht zudem erstmals eine In-situ-Detektion des Anrisses sowie eine Verfolgung des Rissfortschrittes im Brennraumdach. Der vorliegende Artikel stellt das Prüfkonzept und die Ergebnisse eines Variantenvergleichs von konstruktiv identischen Zylinderköpfen mit unterschiedlichen Aluminium-Gusslegierungen vor.

This paper presents an assessment on fatigue crack propagation (FCG) behaviour and fractography observation of an aluminum alloy that was exposed under spectrum loadings. The FCG test has three types of cyclic loadings, namely, constant-amplitude loading (CAL) as well as high-to-low and low-to-high sequence loadings. All three have been performed with the Al6061-T6 specimens. The tests were performed using a 100 kN servo-hydraulic fatigue testing machine according to ASTM E647 standard. The results show that fatigue crack propagation and its fractography were influenced by the load interaction and the sequence, which affect the fracture behaviour of aluminum alloys. The fracture surface exhibited irregular local striation spacings under the spectrum loading. Moreover, the micrographs show increased plasticity throughout the crack propagation compared to CAL.

In this study, 10 mm thick AISI 1040 and AISI 304 steel plates were welded in the butt position without pretreatment by plasma transferred arc (PTA) welding technique. Therefore, mechanical behaviour, microstructure, penetration depth and length were investigated. After welding, microstructural changes in the interface regions of the welded specimens were examined by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). Micro-hardness as well as V-notch Charpy tests were performed to determine the mechanical properties of the welds. The influence of the welding parameters on the dimension and shape of the joints has been found out. From the results, it was derived that with the parameters used, a partly keyhole weld bead formed with a penetration depth of 10 mm and a width of 11 mm in butt position.

Silver foams with 70% porosity have been produced by the sintering and dissolution process (SDP) of fine silver powder. The powder was obtained from the reduction of rod-shaped silver sulfate, using glycerol mixed with sodium hydroxide as reducer and reaction accelerator, respectively. The foam shows three-level porosities, ranging from nanometer to millimeter level. The nanopores were created during the reduction process. The micropores were formed by the dissolution of remaining silver sulfate. The millipores were made from the removal of disaccharide powders. The pore architecture is unique and can be tailored by varying material and process parameters such as silver sulfate and disaccharide morphologies, reduction temperature and time as well as volume fraction of materials.

The goal of this study is to investigate the effect of friction time on mechanical and microstructural properties of dissimilar AISI 1040/AISI 2205 stainless steel couples. The experiments were carried out with continuous drive friction welding set-up. Friction welding experiments with different frictional times and constant friction pressure as well as rotational speed were carried out. The strength of the welds was determined by tensile strength tests. Hardness variation of the joint was also obtained. The results were compared with those of previous studies. The results of applied tests and observations showed that the properties of microstructure change and that the interface temperature increases with friction time. The best tensile strength of the joint was observed for the specimen welded at 1700 rpm rotation speed and a friction time of 3 s.

Application of deep cryogenic treatment instead of conventional heat treatment showed an increase in wear resistance of tools made of high speed steel which are exposed to very complex and demanding conditions in exploitation. The purpose of this study was to investigate the effect of deep cryogenic treatment in combination with plasma nitriding on the tribological properties of powder metallurgy high speed steel, grade PM S390 MC. On treated specimens hardness and fracture toughness was determined, the resistance to intensive adhesive wear (galling) and dry sliding wear (dry sliding wear resistance) were also tested. Test results show that deep cryogenic treatment in combination with plasma nitdriding contributes to better abrasive wear resistance and better galling properties of tested powder metallurgy high speed steel.

The aim of this study is to investigate effects on the residual stresses of the fibre orientations and stacking sequences of the inverted-tooth chains which are made of transversely reinforced steel fibre thermoplastic laminated composite materials. For this purpose, fifteen different tooth chain models were created and stress analysis was performed with ANSYS 11.0 finite element program. For each fibre orientation and stacking sequence values of the yield loads where yielding of the inverted-tooth chain just initiates were determined. Then, loads subjected to the inverted-tooth chains were incrementally increased beyond the yield limits to determine plastic and residual stresses that were obtained by removing applied loads from the inverted-tooth chain. As a result of the analysis, it was observed that all values of residual stress components increased depending on the rising applied loads for all fibre orientation as well as for all stacking sequences.

AA6061/Al alloy chips of different size and fly ash particles have been recycled using the solid state process. The effect of chip size and fly ash content on the microstructure, mechanical and wear properties of the recycled AA6061/Al two phase composites were investigated. Microstructural characterization revealed a uniform distribution of fly ash particles in recycled composites with fine chips and a good interface between fly ash particulates and AA6061/Al two phase matrixes. According to mechanical and wear results, the incorporation of fly ash particles in the AA6061/Al two phase matrix caused reasonable increase in hardness, compressive strength, and wear resistance. On the recycled composites fine chips, the destructive action of the steel ball was very limited compared to that of the Al 2 O 3 ball.

Kurzfassung Das Bunthärten wird traditionell zur hochwertigen, ästhetischen Oberflächenveredelung ferritisch-perlitischer Stähle vor allem für Komponenten von Jagd- und Sportwaffen verwendet. Diese weltweit von wenigen Werkstätten praktizierte Technologie war bisher empirisch orientiert und wurde weitgehend geheim gehalten. Die Struktur der buntgehärteten Randschichten wird hier mit der relativ neuen Methode der Glimmentladungsanalyse (GD-OES) untersucht und mit den Herstellungsparametern korreliert. Eine hochwertige Bunthärtung mit gewünschter marmorierter Farbstruktur und guten mechanischen und chemischen Eigenschaften ist an die Bildung von mehreren charakteristischen Randschichten mit typischen Kennwerten der chemischen Zusammensetzung, Struktur, Gefüge und deren Tiefenprofilen gebunden. Die untersuchten unlegierten und niedriglegierten Stähle haben vergleichbare Schichten, die durch technologie- und werkstoffspezifische Parameter erreicht werden.

Tin and lead based alloys are widely used as journal bearing materials in tribological applications. If Al or Zn with their sliding property will be added to such materials the tribological properties of journal bearings can be improved once more. In this study, wear properties of these journal bearings manufactured from SnPbAlZn, pure Sn, pure Pb, pure Al, and pure Zn bearings were investigated. Experiments were carried out in every 30 min for the total of 150 min by using radial journal bearing wear test rig. As a result wear properties can be improved by variation of SnPbAlZn material.