Neu entwickelte TiAl‐Basislegierungen für den Leichtbau von Triebwerks‐ und Motorkomponenten – Eigenschaften,Herstellung, Anwendung

Newly Developed TiAl Base Alloys for Lightweight Components in Jet Engines and Internal Combustion Engines – Properties, Production, Application Titanium aluminides are a most promising high temperature materials alternative to conventional heat‐resistant steels and superalloys for high‐performance automotive and aircraft engine applications. Intermetallic TiAl base alloys offer striking advantages for high temperature and mechanical loading applications. The specific weight of about 3.8 ‐ 4.1 g/ccm is low, the oxidation and burn resistance at temperatures up to 800 °C are good. The elastic stiffness is high and the temperature strength is enhanced. Feasible applications in combustion engines are valves, pistons and exhaust gas turbocharger rotors. Blades, vanes and discs for jet engines are under development, as well. Due to the extraordinary high specific Young’s modulus (ca. 46 GPa ccm/g) and 0.2 %‐yield strength up to 1 GPa of the TiAl base alloys in the as‐extruded state some applications at lower temperatures have also been taken into consideration, e.g. connecting rods and piston pins. The paper reviews constitutional related properties of the advanced TiAl base alloys with the respect to the industrial manufacturing of components and structural applications.     

PVD‐Nanocomposite‐Beschichtungen für die Zerspanungs‐ und Umformtechnik

PVD Nanocomposite coatings for the machine cutting and deformation technique Physically and chemically separated wear‐protection layers exhibit increasingly more complex structures. Similarly to the a coil of compact materials increase also here solutions develop as composite materials, which are offered in the form of Nanocomposites. An industrially available solution represents the system MeN/Si₃N₄. This is to be introduced concerning its characteristics as well as its application type within the range of the machine cutting and deformation technique.     

Charakterisierung des Ermüdungsverhaltens hochbeanspruchter Eisenbahnvollräder für den Hochgeschwindigkeitspersonenverkehr bei betriebsrelevanten Temperaturen

Fatigue assessment of highly loaded railway monobloc‐wheels for application in high‐speed passenger‐traffic trains under thermal service conditions Railway wheel steels rank among the most loaded components of railway vehicles. Whereas increasing driving speeds increase in particular the cyclic mechanical loading, increasing acceleration and braking torques lead to enormous thermal loads. Hence, a detailed knowledge about the microstructure‐related characterisation of the fatigue behaviour of railway wheel steels under thermal service conditions is the fundamental precondition for a save and economic operation of railway systems. Current investigations concentrate on the fatigue behaviour of actual UIC‐conform high‐speed passenger‐traffic railway wheel steels, which were provided in industrial relevant heat treatment conditions. Microstructural gradients are a consequence of the industrial heat treatment and the size of the component. Specimens were machined from defined depth positions of the wheel rim from original monobloc wheels. Plastic strain amplitude, change in temperature and change in electrical resistance measurement techniques were used to characterise the fatigue behaviour in detail. The specimen position and therefore the local microstructure influence the fatigue behaviour in a characteristic manner.     

Ermittlung von Berechnungskennwerten an Karosseriewerkstoffen – Bericht über ein Gemeinschaftsprojekt der Stahl‐ und Automobilindustrie

Determination of input data for numerical design of sheet steels – Report on a common research project of the steel and automotive industry Within the scope of a common research project of the steel and automotive industry, 20 sheet steels have been investigated to obtain input data for FE‐analysis. In detail, elastic, plastic and fatique characteristical values were determined by several testing institutes for a period of 3 years. The investigated sheet steels differ with regard to the microstructure and the steel concept. Beside several ferritic steels, multiphase steels like dual phase‐, complex phase‐ and TRIP steels as well as 2 austenitic stainless steels were characterised. The starting materials and selected steels with a defined predeformation and heat treatment were investigated. Within this project, the partners developed a testing and documentation precept in which the ways and means were fixed to reach the defined steel condition and to enable a standardised testing and data output for the material database, realised by the automotive industry. Before the actual elastic, plastic and fatique testing, a reception test for all steels was carried out to characterise the materials with regard to the microstructure, surface condition, chemical composition and mechanical properties, obtained in the quasistatic tensile test. The results of the different testing institutes (elastic, plastic and fatique) will be presented in separate publications in detail. As a result of this project it became obvious that the investigated steels can be divided into steel groups which show a similar strain hardening behaviour. Thus, a prediction of mechanical values and flow curves for cognate steels within one steel group seems to be possible. This subject will be the focus of further investigations within the scope of a new project started on January 1^st, 2003.     

Erprobungsmethodik für zyklisch überelastisch beanspruchte Bauteile unter Torsion – Bauschinger‐Kenngrößen für 54SiCr6

Power transmission contains several torsion‐stressed parts. Especially shafts and springs are numerous considered. Helical springs as a special type of springs are mainly stressed by torsion load. During operation the spring's load is basically elastic. In some cases, like overload or machine disaster, the load exceeds the spring's yield stress. For a single event the deformations can be calculated easily by using flow charts. However in other cases the spring will be stressed several times with alternating plastic load. Therefore the calculation will not be as easy as in the single load case. Especially the hardening and softening mechanisms have major influence on material behavior. For high strength steel this material behavior is not fully investigated right now. Present article shows a way how to investigate several important Bauschinger parameters based on plastic torsion load for the high strength steel 54SiCr6. Finally it can be shown that 54SiCr6 is influenced by the Bauschinger effect. On the other hand the needed material characteristic can be investigated by the shown methodology. Based on the identified data, analytical and numerical calculation of alternating plastic torsion load can be done.     

Bandsägen für die Steinbearbeitung – aktuelle Technologieentwicklung

Bandsawing machines for stone cutting – state of the art Due to an EU‐research‐project BaSST a new process was developed to cut slabs and tiles in granite, marble and sandstone out of a huge stoneblock by means of a bandsaw. Such natural stones are very hard, the cutting forces generated to the sawband have to be limited. This was realized with a pivoting sawband, which allows to vary the effective length of engagement depending of the dimension of the material. Simoultaneausly a sawband with diamond cutting segments was developed and tested. Over a long period of optimization a long lifetime of the sawband was reached. The end of the service life was determined by normal wear of the cutting segments and not by breakage of the sawband together with very high cutting rates and excellent cutting surfaces. The outstanding advantage of this new cutting process is a high flexibility for the production, so far unknown till now, a very good cut quality and a remarkable reduced waste of material due to the thin sawband. The number of slabs cut from a block can be doupled due to the thin kerf of the sawband. The new cutting process allows to cut slabs and tiles from a block in a very economic way and under best environmental conditions.     

Performance labels for assessing the sustainability of buildings – from offices to detached and semi‐detached houses / Gütesiegel für die Nachhaltigkeitsbewertung von Gebäuden – Vom Bürobau bis zu Ein‐ bis Zweifamilienwohnhäusern

For some time now, certain types of buildings in Germany have been required to undergo a sustainability assessment. Increasingly, that now also includes residential buildings. A research project is currently underway to develop and test suitable criteria for the assessment of small residential buildings, the preliminary results of which were showcased at the BAU 2015 trade fair in Munich. With the help of examples, this article presents the criteria and provides some information on their application.     

National Standards of the People’s Republic of China – Thoughts of revision on technical specification for application of autoclaved aerated concrete / Nationale Standards der Volksrepublik China – Gedanken zur Überarbeitung der technischen Spezifikationen für die Anwendung von dampfgehärtetem Porenbeton

The revision task on technical specification for application of autoclaved aerated concrete products JGJ/T17 is under way, which was assigned in November 2013.The framework, thoughts and contents of revision on the specification are presented in this paper.