Kennametal (Germany)

This research explores the practicality of fusing Stellite 6, a cobalt-chromium alloy known for its high performance, with stainless steel, utilizing various laser welding approaches. The primary challenge addressed is the joining of dissimilar materials, which presents obstacles such as divergent melting points and disparate coefficients of thermal expansion. The aim is to achieve a metallurgical bond between Stellite and stainless steel that retains desirable properties. The study employs both continuous wave and femtosecond laser welding techniques, subjecting the resultant joints to rigorous analysis to assess their impact on the properties of the bond. Initial tensile testing delineated the intrinsic mechanical characteristics of the materials, revealing that while Stellite exhibits a lower ultimate tensile strength, it compensates with greater elongation compared to stainless steel. The use of continuous wave laser welding proved to be capable of creating the bond; however, it also precipitated a considerable decline in the tensile strength of the Stellite component as a result of the thermal processing involved. In contrast, femtosecond laser welding emerged as a more effective method, enhancing the joint’s overall strength and ductility. This improvement is attributed to the femtosecond laser’s precise control over thermal exposure, which confines the heat to the intended weld zone, thereby safeguarding the adjacent material from damage. Further insights were gleaned from Scanning Electron Microscopy, which showed a preferable intergranular fracture in samples welded with the femtosecond laser—a feature typically associated with ductile failure modes. The femtosecond laser welding approach culminated in a joint efficiency of 53.7%, mirroring the innate yield strength of the Stellite wire. This outcome suggests that such welded joints possess the requisite robustness for practical deployment, thus underscoring the potential of femtosecond laser welding in applications requiring the joining of Stellite to stainless steel.

Nach der „Struktur“ nun zur „Anarchie“. In der Philosophie steht „Anarchie“ fur einen gesellschaftlichen Zustand, in dem eine minimale Gewaltausubung durch Institutionen und maximale Selbstverantwortung des Einzelnen vorherrscht. Wir pladieren fur Anarchie in der Ideation, weil wir jeden Eingriff – sei es durch Hierarchie, Methodenlehre oder Gruppendynamik – in das freie Denken der Menschen ablehnen. Alles, was die Freiheitsgrade verringert, ist schlecht. Die erodierenden Prozesse des Nutzlichen, des Machbaren und des Opportunen setzen fruh genug ein, wenn es darum geht aus Ideen Geschaftsmodelle zu bauen. Die Ideation ist ein freier kindlicher Spielplatz, der von allem kompromittierenden Material freigehalten und geschutzt werden muss.

In this study, the effect of increasing aluminum content and magnetic steering field strength on the structure and wear behavior of arc PVD AlTiN coatings is discussed. Deposition was done by means of an industrial-scale PVD unit for tool coating. The aluminium content in the AlTi source material was increased from 67 to 73 at.%. We applied two settings of the magnetic field that steers the arc across the cathode surface thereby evaporating the AlTi alloy differently. The resulting coating thickness ranged from 3.5 to about 7 µm. Cemented tungsten carbide was used as substrate material. Coating properties like hardness, adhesion, and crystal phases were analyzed by indentation and X-ray diffraction, respectively. The wear behaviour of the different AlTiN hard coatings were investigated in two ways. In a first idealized test, cyclic impacting was done applying a constant force. The resulting wear pattern was quantified by an Alicona multi-focus microscope. A second wear test was done by metal cutting under realistic conditions. Fly milling of ductile cast iron (EN-GJS-700) was performed with regular interruptions in order to measure the increasing wear mark. As expected, aluminium contents above 67 at.% (in the metal fraction of the coating) lead to a decreased wear resistance as the soft hexagonal phase exceeds values of a few vol.%. However, it was found that the formation of the hexagonal phase can be effectively influenced and delayed by increasing the magnetic steering field at the cathode. The wear behavior observed in cyclic impact testing corresponds well to results obtained with the more complex loading situation encountered in milling.

<div class="section abstract"><div class="htmlview paragraph">Over the last few years, many aircraft production lines have seen their production rate increase. In some cases, to avoid bottlenecks in the assembly lines, the productivity of processes needs to be improved while keeping existing machine-tools.</div><div class="htmlview paragraph">In this context, the case of drilling machine-tools tends to require particular attention, especially when multi-material parts are drilled. In such instances, the Vibration Assisted Drilling (VAD) process can be a way to improve productivity and reliability while keeping quality standards.</div><div class="htmlview paragraph">This article presents a case of a drilling/countersinking process for stainless steel and titanium stack parts. Firstly, the article assesses the feasibility and benefits of using Vibration Assisted Drilling and Countersinking with the current cutting-tools. Secondly, it studies the consequences of introducing a new tool holder in the process, which combines the V.A.D. function, a new declutching function and the ability to control countersink depth. Thirdly, a process study is undertaken on these last developments in order to design more efficient cutting tool geometries. New drilling and countersinking combined tools are developed. Their performances when used with the V.A.D. process are highlighted, in terms of productivity, reliability and quality.</div></div>

Abstract: Middle names in Denmark have a long and varied history. Today, approximately one in three Danes has a middle name; until the 19th century, however, such names were used almost exclusively among the nobility, with lesser usage among the clergy and bourgeoisie. During the 19th century, Denmark underwent profound societal changes and saw the introduction of restrictive naming legislation. These may have had an impact on the increasing usage of middle names across a larger part of the population, which can be read out of a comparison of the names registered in the Danish censuses of 1787 and 1880.

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.