EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Grain microstructures formed during solidification processes have a large influence on the mechanical properties of cast metals and alloys. The Cellular Automaton – Finite Element (CAFE) method is a method for simulating grain microstructures coupled with thermal evolution at a scale of approximately one liter. In the classical CAFE method, only the envelop of dendritic grains is modeled on a...

Quantitative modeling of solidification microstructures growing under the influence of convection is a challenging multiscale problem. It is of particular interest in processes where strong flow is present, such as centrifugal casting of Ti–Al alloys, where hypergravity strongly reinforces the buoyancy-driven flow. We present the coupling of the mesoscopic envelope model for dendritic...

During solidification processing of metals and alloys, buoyant flow of thermal and/or solutal origin is known to significantly affect microstructure selection. Here, we use a multiscale Dendritic Needle Network (DNN) model for directional solidification with buoyant liquid flow, in order to study the effect of gravity on the growth dynamics of dendritic arrays. First, we compare our simulation...

In alloy casting, primary dendrite arm spacings (PDAS) affect the mechanical properties of individual grains, solute (micro)segregation, defects (e.g. freckles), but also electrochemical properties (e.g. corrosion resistance). Moreover, in the same alloy, the PDAS may vary by orders of magnitudes when processed under different conditions. Usual models rely on power laws linking PDAS to...

Out-of-equilibrium phase transformation is the main phenomenon controlling the chemical partitioning of elements at micro-scale during additive manufacturing, impacting as a result the isotropy of microstructures. Currently, the behavior of out-of-equilibrium interfaces is not well understood, although it is mandatory for investigating the formation of microstructures. This lack of...

Understand and control the growth of intermetallic phases between dissimilar alloys is the key factor in optimizing the bond strength of hybrids produced by compound casting. Being able to predict the final state of a cast part is the driving force to the development of mathematical models and numerical methods that can represent the phenomena and be applied to assist the interpretation of...

Studies on the formation of layered peritectic solidification structures have been carried out by using the model system TRIS-NPG (tris[hydroxymethyl]aminomethane - neopentylglycol). As such structures are highly affected by thermo-solutal convection, further studies are planned aboard the International Space Station in 2020/21. Since convection is always present on earth, the required process...

SiMoCr spheroidal graphite cast irons contain a high silicon content (>3.8%) as well as molybdenum and chromium. Silicon provides a solid solution strengthened ferritic matrix while chromium and molybdenum contribute to the formation of carbides and influence the amount and properties of perlite. These alloying elements thus increase strength indicators at the expense of ductility and impact...

The understanding of columnar dendrite growth is essential for microstructure modelling. In additive manufacturing, direct measurement of the growth velocity or undercooling is difficult. To use the undercooling and growth velocity as a tool to control the microstructure, thermal modelling with growth kinetics is meaningful.
The classic approximate dendrite growth model based on the Ivantsov...

The formation process of equiaxed structure is a very complicated phenomenon including the dendrite growth, advection and diffusion of heat and solute, liquid flow, solid motion, and so on. We have developed the multi-phase-field lattice Boltzmann (MPF-LB) model to express the formation process of equiaxed structure [S. Sakane et al., Comp. Mater. Sci. 178 (2020) 109639, T. Takaki et al.,...

Magnesium alloys offer promising routes for weight reduction in structural applications, e.g. potentially leading to significant energy savings in the transportation sector. During Mg alloys solidification, primary dendrites typically solidify with a hexagonal close packed (hcp) structure, which has been relatively less explored than its cubic-symmetry counterparts. In this work, using...

A key advantage of additive manufacturing is that it provides a means for producing parts with complex shapes unavailable for other solidification techniques. Another advantage of the method is that the very high cooling rates in the melt pool can result in solids with very fine microstructure and therefore improved mechanical properties. The subject of this presentation is our phase-field...

In the phase-field simulation of columnar dendrite growth, it is essential to treat multiple dendrites because columnar structure is formed through competitive growth between multiple dendrites. Meanwhile, the computational cost of phase-field simulation is very high due to the diffuse interface model. Thus, we developed a large-scale phase-field simulation scheme of columnar dendrite growth...

Continuous casting is nowadays the world leading technology for the steel production. The thin slab casting (TSC) is featured by a slab shape close to the final products, which are casted at a high speed with the fast solidification rate. The quality of the thin slabs strongly depends on the uniformity of the turbulent flow, the super-heat distribution, and the growth of the solidified shell...

Ultra pure metals have various applications in biology or electronics. Crystallization from the melt, e. g. via zone melting, accompanied with segregation of impurities at the solidification front is the basic mechanism behind many different processes for the refining of metals and semi-metals. In this presentation, we focus on a crystallization methodology with a gas cooled (cooling...

High pressure die casting (HPDC) is an increasingly important production process for large components and thin-walled housings. When geometries combine large thin areas with volumetric areas, defects due to misrun, cold shut, air entrainment and porosity can be found in one part and influence each other. The simulation based process optimization must describe these defects in a fully coupled...

Electrofusion is a foundry-like process at extremely high temperatures (1 850°C) to produce refractory blocks. The annealing of the ingot lasts several days/weeks. The blocks are composed of Alumina-Zirconia-Silica (AZS) and a header is casted above the block to keep the macro-porosity outside of the useful section of the ingot. As temperature lowers, a macro-porosity is created inside the...

This work describes the application of the discrete approximate meshless method with the explicit Euler time scheme for simulating the solidification of a binary alloy with grain motion in a square cavity. The volume-averaged physical model couples mass, momentum, species, and energy transport equations by dividing the flow into the porous region with stationary solid phase and into the slurry...

Metal Matrix Composites (MMC) reinforced with nanoparticles are becoming increasingly important in the field of foundry industry in order to increase the mechanical properties of light weight metals. Motion and distribution of nanoparticles during solidification play a dominant role in defining the quality of final cast products. This requires modelling and simulation to bridge the gap between...

The gravity sand casting process is ensuring to achieving 20% low mechanical properties than that of a permanent mold casting because of low rate of solidification. A considerable amount of research and development has concentrated in studying how the resulting mechanical properties are linked to the solidification process in sand gravity casting. In order to simulate the complex physical...

In continuous casting of Ultra-Low Carbon (ULC) steel grade, adding Ti leads to increases clogging tendency in Submerged Entry Nozzle (SEN) comparing Ti-free ULC. Two key mechanisms have been proposed for it: (1) formation of solid oxide due to the chemical reactions on the SEN refractory wall, called ‘early stage’ and (2) deposition of suspended solid non-metallic inclusions (NMIs) on the SEN...