J. Szajnar

Influence of magnetic field and inoculation on size reduction in pure aluminium structure

The main aim of this study was to determine common influences of two different refinement methods on EN AW-Al99,98 primary structure and developing of refinement mechanism. The first method is inoculation with small amount of (Ti+B) less than obligatory standard PN-EN 573-3 and the second method is influence of electromagnetic field on aluminium crystallisation process. These methods of structure refinement are particularly important in continuous and semicontinuous casting where products are used for plastic forming. Large columnar crystals zone result in forces extrusion rate reduction and during the ingot rolling delamination of external layers can occur. [Received on 30 March 2006; Accepted on 12 February 2007]

Heredity of the Structure and Properties of Grey Cast Iron Melted on a Basis of Steel Scrap

In this paper are presented the results of researches, obtained during cast iron melting on basis of steel scrap and a carburizer (without pig iron in solid charge). In the process of carburization, there were used the carburizers such as anthracite, natural and synthetic graphite, petroleum and cupola coke, as well as charcoal. The grey cast iron was produced, for which quantitative analysis of graphite precipitations was performed. It was noticed that in case of using anthracite as carburizer, the smaller graphite precipitations were obtained. In authors’ opinion they are consequences of anthracite structure, consisted of fine graphite flakes and phenomenon of charge materials features’ transfer into melted alloys (structure heredity).

Carburizer Effect on Cast Iron Solidification

This paper presents the effect of carburizing materials on cast iron solidification and crystallization. The studies consisted of cast iron preparation from steel scrap and different carburizers. For a comparison, pig iron was exclusively used in a solid charge. Crystallization analysis revealed the influence of the carburizer material on the crystallization curves as well as differences in the solidification paths of cast iron prepared with the use of different charge materials. The carburizers’ influence on undercooling during the eutectic crystallization process was analyzed. The lowest undercooling rate was recorded for the melt with pig iron, then for synthetic graphite, natural graphite, anthracite, and petroleum coke (the highest undercooling rate). So a hypothesis was formulated that eutectic cells are created most effectively with the presence of carbon from pig iron (the highest nucleation potential), and then for the graphite materials (crystallographic similarity with the carbon precipitation in the cast iron). The most difficult eutectic crystallization is for anthracite and petroleum coke (higher undercooling is necessary). This knowledge can be crucial when the foundry plant is going to change the solid charge composition replacing the pig iron by steel scrap and the recarburization process.

Microstructure of the Synthetic Cast Iron Carburized with Different Types of Carburizers

The cast iron melting process can be based on metallic charge with pig iron or on steel scrap exclusively (i.e. synthetic cast iron). The analysis of the synthetic cast iron microstructure was presented and compared to micros of the cast iron produced on the base of pig iron. The analysis consisted of size and shape of the graphite precipitations and the metal matrix structure, too. The results of examinations and calculations were presented in form of figures and graphite distribution histograms. Based on researches conducted the authors confirmed opinions of heredity of the alloys microstructure cited in the literature.

Primary Structure and Mechanical Properties of AlSi2 Alloy Continuous Ingots

The paper presents the research results of horizontal continuous casting of ingots of aluminium alloy containing 2% wt. silicon (AlSi2). Together with the casting velocity (velocity of ingot movement) we considered the influence of electromagnetic stirring in the area of the continuous casting mould on refinement of the ingot’s primary structure and their selected mechanical properties, i.e. tensile strength, yield strength, hardness and elongation. The effect of primary structure refinement and mechanical properties obtained by electromagnetic stirring was compared with refinement obtained by using traditional inoculation, which consists in introducing additives, i.e. Ti, B and Sr, to the metal bath. On the basis of the obtained results we confirmed that inoculation done by electromagnetic stirring in the range of the continuous casting mould guarantees improved mechanical properties and also decreases the negative influence of casting velocity, thus increasing the structure of AlSi2 continuous ingots.

Diphase stream force in pneumatic powder injection

The method of introduction of reagents into liquid alloys by use of pneumatic injection is well known since many years. In most cases, the submerged lance is used, but sometimes this is difficult or impossible at all. This is the reason why the authors had made some experiments in the field of powders injection with non-submerged lance. The main method was measurement and recording of diphase stream force value with use of laboratory stand connected to PC computer with dedicated software. The next step was making graphs showing the character of force and calculation of stream parameters. The last step was formulation of statistical equations which shows the relationship between parameters of the process. Future experiments are planned with use of CDF Fluent 6.2 program for checking the results in computer simulations. The obtained results should interest everyone who is interested in improving the melting process by pneumatic techniques. [Received 5 November 2007, Accepted 9 November 2007]

Inoculation of aluminium EN AW-Al99,5 structure

The main aim of studies was to determine common influences of two different refinement methods on EN AW-Al99,5 primary structure and developing of refinement mechanism. The first method is inoculation with small amount of (Ti+B) less than obligatory standard PN-EN 573-3 and the second method is influence of electromagnetic field on aluminium crystallisation process. These methods of structure refinement are particularly important in continuous and semi-continuous casting where products are used for plastic forming. Large columnar crystals zone result in forces extrusion rate reduction and during the ingot rolling delamination of external layers can occur. [Received 17 October 2006; Accepted 15 May 2007]