Laser beam melting of aluminum alloys with hull-core build strategy by using an initial meso-scale simulation

Laser beam melting (LBM) of aluminum alloys is gaining a wide popularity in different industrial applications as an alternative technology for the production of individual and complex parts. A long build time and the high amount of experimental work for optimizing or finding new process parameters are two of the current challenges for reaching an industrial maturity. This paper proposes an efficient way to determine new process parameters for aluminum alloy aluminum-silicon10-magnesium with highest build-up rates by using a 3D finite element model on the mesoscopic level. High laser power in combination with the hull-core build strategy was used to increase the build-up rate without impairing the part accuracy. The influences of high laser power, laser diameter and scan speed on the melt pool were studied by using a thermal simulation of single laser tracks. Based on the simulation results the process window could be derived and was tested on a laser beam melting (LBM) system. The achieved reduction of the build time of up to 31 % without loss in part accuracy proved the novel approach for the prediction of the required process window as an efficient method to reduce costly and time-consuming experimental work.     

CFD in der chemischen Verfahrenstechnik aus industrieller Sicht

Computational fluid dynamics (CFD) is increasingly becoming established as a tool for analysis and design in the chemical industry. Several projects from various areas are introduced as examples of CFD projects from the perspective of the CFD user in chemical industry. The areas chosen are based on those in a process chain: transportation, mixing, reaction, and separation of materials. The most important steps and decisions in the use of CFD are presented from the perspective of the process engineer. This paper attempts to convey an appreciation for the possibilities and opportunities, but also for the limits of computational fluid dynamics.     

Entwicklung von Werkstoffmodellen zur Beschreibung der lokalen Eigenschaften der Wärmeeinflusszone von hochfesten Feinblechen

The analysis of the complete process chain is an important requirement in the fine sheet metal working for the improvement of strength evaluation of structures and components. Particularly at applications of high‐strength steel sheets the development of material properties as well as the production process play a decisive role, because of the complex requirement profile these steels have to satisfy. In the context of the represented research the material reactions were experimental examined on the basis of the thermal effect of different joining processes at multiphase steel. The investigations were accomplished on HCT600XD, HCT780XD, SZBS800 and LH800. Exemplarily the article discusses the procedures and the results of the research of HCT600XD and SZBS800.     

Numerische Untersuchung der reaktiven Trennwandkolonne am Beispiel der Methylacetat‐Hydrolyse

The reactive dividing wall column concept provides an opportunity to combine the advantages of dividing wall columns and reactive distillation in one single unit. Due to the novelty of this complex process, extensive numerical investigations are necessary. For this purpose, a simulation tool has been developed, which applies the rigorous rate‐based modelling approach. The successful validation of both the model and simulation tool are presented.     

Linearisierte Darstellung des Diffusionskoeffizienten von Kohlenstoff in austenitischem Eisen

Linearized Representation of the Diffusivity of Carbon in Austenitic Iron Using three independent literature sources, linearized representations for the diffusivity of carbon in austenite as a function of the concentration from 0 to 1.4 m.% C are derived and fitted with respect to temperature in the range most relevant to heat treatment of steels between 800 and 1100 °C by means of two appropriate defining equations based on a polynomial and Arrhenius approach, respectively. The mathematical evaluation of a gas carburizing experiments demonstrates the potential of the new formulation. A comparison with available literature data is drawn.