1.
P. GRÖNING
Hüttenes-Albertus Chemische Werke GmbH, Germany
SUSTAINABLE COLD BOX SYSTEMS

2.
D. Franzen, P. Martin, B. Pustal, A. Bührig-Polaczek
Foundry Institute RWTH Aachen, Germany
EVALUATION OF STATIC AND DYNAMIC MECHANICAL PROPERTIES UNDER THE INFLUENCE OF ALLOYING DESIGN IN DUCTILE CAST IRON

3.
J. Medved¹, M. Godec², I. Paulin², S. Kores³, M. Vončina¹¹University of Ljubljana, Faculty of Natural Sciences and Engineering, Department for Materials and Metallurgy, Slovenia
²Institute of Metals and Technology, Slovenia
³Talum Tovarna aluminija d. d. Kidričevo, Slovenia
CHEMICAL, MECHANICAL AND HEAT WEAR OF TOOLS IN CAST ALUMINIUM ALLOYS

1.
P. GRÖNING
Hüttenes-Albertus Chemische Werke GmbH, Germany

SUSTAINABLE COLD BOX SYSTEMS

Summary

The foundry industry has always had to adapt to changing economic and political conditions. Increasing specialization and growing complexity in combination with increased environmental requirements also demand the use of specialized binders. Due to the wide variety of applications and tasks, it is necessary to provide a correspondingly extensive product range. The organic binder systems and above all the Cold Box process are still the dominant core production processes, especially in serial casting.
Sustainable foundry chemistry?
Is there even such a thing as sustainable foundry chemistry? If youare being honest, the answer is likely “no”. No matter which process or system the foundry uses, there is always a “footprint” left by foundry chemicals. Therefore, the task of foundry chemistry is to keep this footprint as small as possible, which involves addressing a wide range of requirements and demands.
Development of modern sustainable Cold Box binders
Modern Cold Box systems must meet the customer's requirements. Standard properties include a high strength level and high reactivity to ensure maximum productivity. Other important properties are thermal stability (deformation behaviour) gas and emission behaviour (pollutants, smoke, odour, condensates). In recent years, the demands placed on foundry residues to be dumped in landfills have also increased significantly. On the one hand, landfill space is becoming increasingly difficult, and on the other hand, the costs of dumping are increasing due to stricter legal requirements. As a result, the focus is increasingly on waste sand parameters such as the Phenol index, BTEX, TOC and DOC.
Sources of femissions from the Cold Box process
Cold Box binder systems must meet a wide range of technological, but also environmentally relevant characteristics. In terms of waste sand, the most relevant parameters are BTEX, Phenol index, TOC and DOC (Fig. 1,2).

2.
D. Franzen, P. Martin, B. Pustal, A. Bührig-Polaczek
Foundry Institute RWTH Aachen, Germany

EVALUATION OF STATIC AND DYNAMIC MECHANICAL PROPERTIES UNDER THE INFLUENCE OF ALLOYING DESIGN IN DUCTILE CAST IRON

Summary

Complex cast iron components are characterized by their various microstructures. Due to their microstructural diversity, ductile iron (DI) offers a wide range of mechanical properties. A high pearlite content leads to a highly wear-resistant material, while a fully ferritic, low-alloyed matrix enables a particularly good ductility and toughness even at low temperatures. In particular, solid solution strengthened DI grades with elevated silicon (Si) contents ranging from 3.2 wt.% to 4.3 wt.% Si are characterized by a significantly higher ductility compared to ferritic-pearlitic DI grades at the same strength. However, toughness properties are a critical factor for these materials, which significantly decrease with increasing silicon content.
The toughness of a material is on the one hand dependent on the microstructure and thus by the alloy design, and on the other hand on the external load applied. While the load case is represented by testing temperature, the strain rate and local stress state, the microstructure is characterized by the formation of the graphite phase, the grain size and the local chemical composition of the matrix.
The local chemical composition of the matrix is represented in particular by the formation of microsegregation profiles, which build up during eutectic solidification and are especially prominent in the case of solid solution strengthened DI due to both the decoupled growth of the eutectic phase and elevated Si contents. Critical Si enrichments in the vicinity of the graphite nodules promote the formation of FeSi superstructures that lead to an embrittlement of the material. It is therefore assumed that the formation of FeSi superstructures provoke additional notch sensitivity that lead to a promotion of crack initiation in these areas. It is further assumed that the formation of superstructures results in the decrease in toughness properties on a macroscopic level.
Recent numerical and experimental investigations show that the silicon microsegregation profile can be influenced by the adjustment of the alloying design. By alloying with 0.3 to 1.2 wt.% aluminum it is possible to invert and precisely modify the microsegregation profile of silicon. Similar tendencies can also be observed when nickel is alloyed. On the basis of the present results, it is assumed that the adaptation of the alloy design represents a suitable metallurgical tool for the selective adjustment of silicon microsegregations and thus for further improving the static and dynamic mechanical properties of modern ductile cast irons.

Keywords: Cast iron, high silicon ductile iron, solid solution strengthening, impact toughness, microsegregation, alloy design

CHEMICAL, MECHANICAL AND HEAT WEAR OF TOOLS IN CAST ALUMINIUM ALLOYS

Summary

Pressure casting is one of the leading casting processes in the modern industry. In the case of pressure casting the melt is in contact with the tool, whereas the chemical interaction between the tools, made of hot-working tool steel, and the melt occur. In addition, mechanical and heat wear of the tools also occurs. High productivity requires high resistance to these factors.
For the experiment, samples from UTOPMO1 and RAVNEX HD were used to test their wear resistance in aluminium alloys Al99.7 and AlSi12. With this aim a laboratory device was designed to test two different tool steels in two different aluminium alloys at two different temperatures for 4 hours at 75 revolutions per minute. The result of the interaction is the growth of a reaction layer, which is formed from three or four layers. The wear resistance of UTOPMO1 tool steel is better in AlSi12 aluminium alloy than in Al99.7, whereas the wear resistance of RAVNEX HD tool steel is much worse in molten casting aluminium alloys. The thickness of the interaction layer increases with the rising temperature.

Keywords: interaction tool steel/molten aluminium, wear resistance, interaction layer, intermetallic phases from system Al-Fe