Thermal analysis and microstructural evaluation of conventional land developed high speed tool steels

Thermal analyses and microstructural evaluation were carried out for the conventional AISI M2 and M10 high speed steels as well as for alloys with varying Nb and/or Ti contents to assess their liquidus, solidus and other high temperature reactions. It has been found that the slope change of cooling curves marks the formation of MC type carbides, while the break is due to the crystallization of delta ferrite and much larger volume fraction of different type of carbides including M6C mostly by eutectic reactions. Results show that the formation of dendrites is the most basic characteristic of the solidification process for the AISI M2 and M10 alloys but for the steels containing niobium and/or titanium carbides, these primary carbides insert an inoculating effect and modify the coarse dendritic structure.     

Technologien zur Speicherung von Wasserstoff. Teil 1: Wasserstoffspeicherung im engeren Sinn

The efficient and dense storage of hydrogen still is a challenge for research and development. Next to compression and liquefaction, there are a number of alternative approaches, which try to enhance storage density by bonding hydrogen to another substance. Physisorbing as well as chemisorbing organic and inorganic carrier systems are possible. Many of these technologies have not yet exceeded the technology readiness level of lab‐scale tests. However, some of the technologies have already reached significantly higher technological levels. The first part of this study discusses storage approaches with recovery of elemental hydrogen.     

Bemessungs‐ und Ausführungshinweise für Aufbeton auf Brückenfahrbahnplatten

Durch die ständige Erhöhung der Verkehrsbelastungen in den letzten Jahrzehnten und durch die Verwendung moderner Fahrzeugrückhaltesysteme sind ältere Brücken häufig nicht mehr in der Lage, ohne Verstärkungsmaßnahmen den Anforderungen des modernen Straßenverkehrs zu genügen. Eine bewährte Methode, die Tragfähigkeit einer Brücke zu erhöhen, besteht darin, auf das entsprechend vorbehandelte Rohtragwerk eine bewehrte Platte, welche mit dem Bestand kraftschlüssig verbunden ist, zu betonieren. Für die Bemessung sind der Eurocode und die in den europäisch technischen Dübelzulassungen (ETA) angegeben Bemessungsvorschriften (ETAG, TR, ...) anzuwenden. Der Anwender steht vor einer Fülle von breit gefächerten Wahlmöglichkeiten innerhalb dieser Vorschriften. Auf Basis der Erkenntnisse von mehreren Versuchsprogrammen gibt in Österreich die RVS 15.02.34 Anweisungen für die Fugenvorbereitung, die Rezeptur und den Einbau des Aufbetons und für die zugehörige Interpretation des Eurocodes und der Dübelbemessungsvorschriften bei der Bemessung der Schubfuge. Design and Detailling of Concrete Overlays Due to a permanent increase of traffic loads during the last decades and due to installation of modern vehicle restraint systems older bridges are often overloaded and thus have to be strengthened. Casting a concrete overlay on the existing structure is a state of the art method in order to increase the bearing capacity. The key is to prepare the interface in a way that no slip will occur between old and new concrete when forces are transferred over the interface. Mandatory for designing the concrete overlay is the Eurocode and in the European Technical Approvals (ETA) for dowels referred design guidelines (ETAG, TR, ...). However, the designer has to choose within a lot of options. On the basis of several research programs the RVS 15.02.34 gives recommendations for the preparation of the old concrete, the composition of the new concrete, casting and curing as well as choosing the associated options of the Eurocode within the structural design and detailing of the interface.     

Procedure for reliable durability validation of train axles

The structural durability of wheelset axles depends on the operational loading as well as on the fatigue strength of axles. To validate an axle design the time‐varying stresses in individual critical areas of the axle, represented by their stress spectra, must be taken into account. The allowable stresses in individual axle areas depend both on the fatigue strength and on the spectrum of operational stresses. The procedure for the axle structural durability validation, presented in this paper, includes the numerical fatigue life estimation as well as the experimental durability approval. Also the influences of axle design, material properties and manufacturing technology on structural durability are discussed.