Herstellung,Mikrostruktur und Korrosionsverhalten der konventionellen und ultrafeinkörnigen Legierung EN AW‐6082

Fabrication, microstructure and corrosion behaviour of the conventional and ultrafine‐grained AA6082 The effect on the corrosion behaviour of the commercially available AlSi1MgMn alloy (AA6082) with ultrafine grains in comparison to coarse grains, i.e. the conventional material state was investigated. The results of the electrochemical experiments are presented in correlation to the microstructure before and after the corresponding examinations. The quantification of the induced corrosion damage as well as the corrosion characteristics shows the reduced susceptibility of the material with ultrafine‐grained microstructure in contrast to the coarse‐grained initial state.     

Ausgewählte Ergebnisse der Untersuchung der Prozesse des Schmelzens und der Erstarrung beim Schmelzschweißen und Schmelzlöten mittels der materiellen Modellierung

In the article a method for the material modelling is described under application of visually transparent materials of the thermal and chemical solidification processes when welding and soldering. All solidification processes carried out independently of the form of the primary crystals, first about the planar one, then cellular and in the end dendritically growth the solidification structure. It is determined by the chemical composition of the weld and soldering good, the weld, soldering, crystallization or solidification speeds and by the temperature gradients at the solidification front particularly. The vacancy concentration is made by the temporary formation of so‐called zipper primary grain boundaries in the solidification structure when welding. Among other things a preferential growth direction of the primary crystals explains itself by the fast growth of so‐called victim crystals which completes the known theories of the preferential growth.     

Wasserstoffversprödung von Feinkornbaustählen in Abhängigkeit von der Legierungszusammensetzung,der Gefügeausbildung und der mechanischen Belastung

The Influence of Chemical Composition, Structure, and Mechanical Strain on the Hydrogen Embrittlement of Fine-Grained Low-Alloy Steels On specimens from fine-grained low-alloy steels StE 51 and StE 36 strain induced hydrogen embrittlement has been studied under increasing, pulsating, and static load conditions in hydrogen sulphide at various strain rates, gas pressures, gas compositions, and surface qualities. Both steels displayed equal sensitivity compared to mild constructional steels, Hydrogen pick-up occurred only during plastic-deformation of the specimens and led mainly to a decrease of the reduction of area and to the formation of side cracks in the necking zone. This type of embrittlement is important for constructions subjected to pulsating load conditions causing plastic deformation in areas with constructional notches. As part of the research and development project “Corrosion and Corrosion Prevention” this investigation was supported by the Federal Ministry of Research and Technology.     

Einfluß des Fe-Gehalts und der Auslagerungszeit auf mechanische,elektrische und magnetische Eigenschaften der Legierung CuNi 10(Fe)

The Influence of the Fe-Content and the Ageing Time on Mechanical, Electric and Magnetic Properties of the Alloy CuNi 10 (Fe) 6 batches of the technical alloy CuNi 10 Fe with Fe-contents varying from 0.04 to 1.52 wt- % were investigated concerning the influence of the Fe-content and of ageing at 400 ° on Vickers hardness, impact properties, tensile strength at 400 °, relative magnetization and electric conductivity. In addition stress rupture tests with continuous strain recording were performed at 400 ° with testing times up to 3000 hrs. The results indicate that when ageing the material at 400 ° the mechanical as well as the physical properties investigated are markedly influenced by the Fe-content in the alloy CuNi 10 Fe. This influence is also clearly perceptible in the stress rupture tests at 400 °. An explanation for this behaviour is given by the formation of Ni-Fe rich precipitates on the grain boundaries as well as in the grain interior in all batches with the exception of those with the lowest Fe-contents     

Gültigkeits- und Anwendungsbereich der Rißbruchmechanik

Fracture Mechanics Range of Validity and Application. The range of validity and application of the linear-elastic and elasto-plastic fracture mechanics is determined according to practicable quantitative criteria. The former is applicable to the low stress brittle fracture in brittle materials, the latter is applicable to the higher stress brittle and tear fracture in tougher materials. The real continuum mechanics fracture criterium is not yet determined. The linear-elastic fracture mechanics is widely applicable to fatigue fractures. Taking into account the interaction and sequence effect of low and high load amplitudes is necessary. The fracture mechanics approach to brittle and fatigue fracture is compared with traditional testing techniques.     

E-Modul und Kriechverhalten von Phenoplasten bei Raumtemperatur. Einfluß der Formstoffzusammensetzung

Relationship Between Composition, Elastic Modulus and Creep of Phenolic Plastics at Room Temperature The mechanical properties of thermosetting material can be modified by the type and quantity of filler or the combination of fillers. By this methode it is possible to produce a certain moulding powder for a certain application. The elastic modulus and the creep are significant values for short-time and long-time mechanical behaviour. The relationship between these both characteristic values and the compositions of moulded materials (multiphase phenolic resin systems) will be discussed.     

Rohr-Innendruck-Zeitstanduntersuchungen bei überlagerter Heißdampf-Korrosion. Ausmaß und Erscheinungsform der spannungsbedingt verstärkten Oberflächen- und Gefüge-Oxidation von Rohrmaterial der Leigierung Incoloy 800

Stress-Rupture Testing under Superimposed Steam Corrosion . Extent and Morphology of Stress-Assisted Surface and Bulk Oxidation of Incoloy Alloy 800 Thin Wall Tubing. Continuing long-time stress-rupture testing under biaxial stresses and superimposed steam corrosion of Incoloy Alloy 800 thin wall tubing, the extent and morphology of stress-assisted additional surface and bulk oxidation was evaluated by quantitative metallography. This paper describes the stress-assisted additional corrosion as function of tangential stress or corresponding rupture-life, creep strain, and creep rate. The results are presented and explained on the basis of surface and bulk penetrating oxide morphology.     

Einfluß der Mahlbedingungen und der Qualität der Ausgangsprodukte auf die Eigenschaften von Al-C-Strangpreßprodukten

Influence of the Crinding Parameters and the Quality of the Starting Materials on the Properties of Extruded AIC Products Dispersion strengthened aluminium has been produced by grinding aluminium powder with carbon black in a high energy ball mill, heat treating of the milled powder and subsequented hot extrusion. Tensile strength, elongation, hardness and impact strength were determined. The influence of griding parameters, such as duration, speed of rotation of the rotation arm and the weight ratio of powder to milling balls on the mechanical properties of the extruded rods were investigated. Other important variables are the oxygen content of the aluminium powder, the quality of the carbon black and additions of control agents such as oil or water.