Markus Daamen

Bio: Markus Daamen is an academic researcher from RWTH Aachen University. The author has contributed to research in topics: Twip & Casting (metalworking). The author has an hindex of 6, co-authored 12 publications receiving 130 citations.

Twin-roll strip casting: A competitive alternative for the production of high-manganese steels with advanced mechanical properties

Abstract: In this work, a high-manganese Fe–29Mn–0.3C TWIP steel was produced by twin-roll strip casting and subjected to additional thermo-mechanical treatment. The evolution of microstructure and texture in each processing condition was investigated and correlated with the corresponding mechanical properties. Due to pronounced microsegregations, chemical gradients and an inhomogeneous microstructure in the as-cast and hot-rolled material, regions of strongly varying stacking fault energy caused undesired austenite–martensite transformation and inhomogeneous mechanical properties. The specimens after additional cold rolling and annealing at temperatures as low as 900 °C revealed a microstructure with a homogeneous grain size distribution and significantly reduced microsegregations. The resulting mechanical properties were comparable to those of industrial advanced high strength steels and TWIP steel produced by conventional processing, where energy-consuming homogenization is necessary. Therefore, twin-roll strip casting offers the possibility for cost-effective processing of TWIP steel with competitive mechanical properties.

Strip Casting of a High-Manganese Steel (FeMn22C0.6) Compared with a Process Chain Consisting of Ingot Casting and Hot Forming

Abstract: In this paper, the capabilities of the thin strip (twin roller) casting method to produce high manganese steel strip are examined. For this purpose a FeMn22C0.6 strip has been cast both using a lab-scale twin roll casting line and a more conventional process chain. The experiments show that the production of high manganese steel strip is feasible with both methods. Differences become apparent in the microstructure and chemical composition. While the strip which was produced by ingot casting and hot forming shows a homogenous grain distribution, the thin-strip-cast one shows a typical casting microstructure, consisting of dendritic and globulitic structures. In addition, the thin-strip-cast steel contains the accurate carbon content, while the hot forming route led to a loss of carbon, which influences the mechanical properties. The good potential of thin-strip casting of high manganese steels, although it still has to be improved, is confirmed.

Microstructure Analysis of High-Manganese TWIP Steels Produced via Strip Casting

Abstract: Steels with manganese contents of more than 20% offer a new and favourable combination of material properties like high strength and high ductility. These extraordinary mechanical properties are based on the TWIP effect, which depends on the Stacking Fault Energy (SFE). But there are still problems in the conventional production of high-manganese steels, which prevents their widespread use. Both in casting and subsequent hot rolling difficulties occur, with the consequence that the production is very expensive. One alternative production process of high-manganese steels is strip casting, which basic feasibility was shown in earlier work. Strip casting allows the casting and rolling of hot strip in one combined process. In this way hot strip with a thickness of less than 3 mm could be produced. Characteristic for the strip cast material is the as-cast structure with a fine dendritic structure, which shows pronounced microsegregations with a short wavelength. The pronounced microsegregations can have an impact on the local chemical composition and thus on the dominating forming mechanisms that occur. In this work therefore the microsegregations of strip cast material are investigated by means of electron probe microanalysis (EPMA) measurement. Besides the local element distribution, also the presence and composition of non-metallic inclusions are analysed. Especially oxides from the casting process and sulfides from the raw material are expected. Furthermore, different annealing processes for the elimination of the dendritic as-cast structure are examined. In these experiments the temperatures were varied in the range from 900 to 1150°C at annealing times from several minutes to a few hours.

A General Perspective of Fe-Mn-Al-C Steels

Abstract: During the last years, the scientific and industrial community has focused on the astonishing properties of Fe-Mn-Al-C steels. These high advanced steels allow high-density reductions about ~15% lighter than conventional steels, high corrosion resistance, high strength (ultimate tensile strength (UTS) ~1 Gpa) and at the same time ductilities above 60%. The increase of the tensile or yield strength and the ductility at the same time is almost a special feature of this kind of new steels, which makes them so interesting for many applications such as in the automotive, armor and mining industry. The control of these properties depends on a complex relationship between the chemical composition of the steel, the test temperature, the external loads and the processing parameters of the steel. This review has been conceived to tried to elucidate these complex relations and gather the most important aspects of Fe-Mn-Al-C steels developed so far.

A general perspective of Fe–Mn–Al–C steels

Abstract: During the last years, the scientific and industrial community has focused on the astonishing properties of Fe–Mn–Al–C steels. These high advanced steels allow high-density reductions about ~ 18% lighter than conventional steels, high corrosion resistance, high strength (ultimate tensile strength ~ 1 Gpa), and at the same time ductility above 60%. The increase in the tensile or yield strength and the ductility at the same time is almost a special feature of this kind of new steels, which makes them so interesting for many applications such as in the automotive, armor, and mining industry. The control of these properties depends on a complex relationship between the chemical composition of the steel, the test temperature, the external loads, and the processing parameters of the steel. This review has been conceived to elucidate these complex relations and gather the most important aspects of Fe–Mn–Al–C steels developed so far.

Identifying Structure–Property Relationships Through DREAM.3D Representative Volume Elements and DAMASK Crystal Plasticity Simulations: An Integrated Computational Materials Engineering Approach

Abstract: Predicting, understanding, and controlling the mechanical behavior is the most important task when designing structural materials. Modern alloy systems—in which multiple deformation mechanisms, phases, and defects are introduced to overcome the inverse strength–ductility relationship—give raise to multiple possibilities for modifying the deformation behavior, rendering traditional, exclusively experimentally-based alloy development workflows inappropriate. For fast and efficient alloy design, it is therefore desirable to predict the mechanical performance of candidate alloys by simulation studies to replace time- and resource-consuming mechanical tests. Simulation tools suitable for this task need to correctly predict the mechanical behavior in dependence of alloy composition, microstructure, texture, phase fractions, and processing history. Here, an integrated computational materials engineering approach based on the open source software packages DREAM.3D and DAMASK (Dusseldorf Advanced Materials Simulation Kit) that enables such virtual material development is presented. More specific, our approach consists of the following three steps: (1) acquire statistical quantities that describe a microstructure, (2) build a representative volume element based on these quantities employing DREAM.3D, and (3) evaluate the representative volume using a predictive crystal plasticity material model provided by DAMASK. Exemplarily, these steps are here conducted for a high-manganese steel.