High-tin bronzes are used for church bells and concert bells (carillons). Therefore, beside their decorative value, they should also offer

other functional properties, including their permanence and good quality of sound. The latter is highly influenced by the structure of bell

material, i.e. mostly by the presence of internal porosity which interferes with vibration of the bell waist and rim, and therefore should be

eliminated. The presented investigations concerning the influence of tin content ranging from 20 to 24 wt% on mechanical properties of

high-tin bronzes allowed to prove the increase in hardness of these alloys with simultaneous decrease in the tensile and the impact

strengths (Rm and KV, respectively) for the increased tin content. Fractures of examined specimens, their porosity and microstructures

were also assessed to explain the observed regularities. A reason of the change in the values of mechanical properties was revealed to be

the change in the shape of α-phase crystals from dendritic to acicular one, and generation of grain structure related to the increased Sn

content in the alloy.

Constantly developing production process and high requirements concerning the quality of glass determine the need for continuous improvement of tools and equipment needed for its production. Such tools like forms, most often made of cast-iron, are characterized by thick wall thickness compared to their overall dimensions and work in difficult conditions such as heating of the surface layer, increase of thermal stresses resulting from the temperature gradient on the wall thickness, occurrence of thermal shock effect, resulting from cyclically changing temperatures during filling and emptying of the mould. There is no best and universal method for assessing how samples subjected to cyclic temperature changes behave. Research on thermal fatigue is a difficult issue, mainly due to the instability of this parameter, which depends on many factors, such as the temperature gradient in which the element works, the type of treatment and the chemical composition of the material. Important parameters for these materials are at high temperature resistance to thermal shock and thermal fatigue what will be presented in this paper.

The results of examinations of the influence of titanium-boron inoculant on the solidification, the microstructure, and the mechanical

properties of AlZn20 alloy are presented. The examinations were carried out for specimens cast both of the non-modified and the

inoculated alloy. There were assessed changes in the alloy overcooling during the first stage of solidification due to the nuclei-forming

influence of the inoculant. The results of quantitative metallographic measurements concerning the refinement of the grain structure of

casting produced in sand moulds are presented. The cooling rate sensitivity of the alloy was proved by revealing changes in morphology of

the α-phase primary crystals. Differences in mechanical properties resulting from the applied casting method and optional inoculation were

evaluated.

The work deals with the influence of change in the filling conditions of the ceramic moulds with plaster binder on the presence of gaseous

porosity and the microstructure of the achieved test castings with graded wall thickness. Castings made of EN AC-44000 alloy, produced

either by gravity casting, or by gravity casting with negative pressure generated around the mould (according to the Vacumetal

technology), or by counter-gravity casting were compared. The results of examinations concerning the density of the produced castings

indicate that no significant change in porosity was found. The increased size of silicon crystals was found for the increased wall

thicknesses due to the slower cooling and solidification of castings.

The presented work is aimed to deal with the influence of changes in the value of negative (relative) pressure maintained in the die

cavity of pressure die casting machine on the surface quality of pressure castings. The examinations were held by means of the

modified Vertacast pressure die casting machine equipped with a vacuum system. Castings were produced for the parameters selected

on the basis of previous experiments, i.e. for the plunger velocity in the second stage of injection at the level of 4 m/s, the pouring

temperature of the alloy equal to 640°C, and the die temperature of 150°C. The examinations were carried on for three selected values

of negative gauge pressure: - 0.03, - 0.05, and - 0.07 MPa. The quality of casting was evaluated by comparing the results of the surface

roughness measurements performed for randomly selected castings. The surface roughness was measured by means of Hommel Tester

T1000. After a series of measurements it was found that the smoothest surface is exhibited by castings produced at negative gauge

pressure value of - 0.07 MPa.

The paper presents the results of investigation into the technological possibility of making light-section castings of GX2CrNiMoN25-6-3

cast steel. For making castings with a wall thickness in the thinnest place as small as below 1 mm, the centrifugal casting technology was

employed. The technology under consideration enables items with high surface quality to be obtained, while providing a reduced

consumption of the charge materials and, as a result, a reduction in the costs of unit casting production.

The paper presents the results of investigations concerning the influence of negative (relative) pressure in the die cavity of high pressure

die casting machine on the porosity of castings made of AlSi9Cu3 alloy. Examinations were carried out for the VertaCast cold chamber

vertical pressure die casting machine equipped with a vacuum system. Experiments were performed for three values of the applied gauge

pressure: -0.3 bar, -0.5 bar, and -0.7 bar, at constant values of other technological parameters, selected during the formerly carried initial

experiments. Porosity of castings was assessed on the basis of microstructure observation and the density measurements performed by the

method of hydrostatic weighing. The performed investigation allowed to find out that – for the examined pressure range – the porosity of

castings decreases linearly with an increase in the absolute value of negative pressure applied to the die cavity. The negative pressure value

of -0.7 bar allows to produce castings exhibiting porosity value less than 1%. Large blowholes arisen probably by occlusion of gaseous

phase during the injection of metal into the die cavity, were found in castings produced at the negative pressure value of -0.3 bar. These

blowholes are placed mostly in regions of local thermal centres and often accompanied by the discontinuities in the form of interdendritic

shrinkage micro-porosity. It was concluded that the high quality AlSi9Cu3 alloy castings able to work in elevated temperatures can be

achieved for the absolute value of the negative pressure applied to the die cavity greater than 0.5 bar at the applied set of other parameters

of pressure die casting machine work.

The performed examinations concerning the process of filling the plaster ceramic moulds with aluminium alloys allowed to assess the

influence of various methods of introducing the metal into the mould cavity on the macro- and microstructure of the obtained experimental

castings. The comparison was performed for castings with graded wall thickness made either of EN AC-44000 alloy or of EN AC-46000

alloy, produced either by gravity casting, or by gravity casting with negative pressure generated around the mould (according to the

Vacumetal technology), or by counter-gravity casting. It was found that the silicon crystals grow in size with an increase in wall thickness

due to the slower cooling and solidification of castings.

The paper presents the method of preparing a composite slurry composed of AlSi11 alloy matrix and 10 vol.% of SiC particles, as well as

the method of its high-pressure die casting and the measurement results concerning the castability of the obtained composite. Composite

castings were produced at various values of the piston velocity in the second stage of injection, diverse intensification pressure values, and

various injection gate width values. There were found the regression equations describing the change of castability of the examined

composite as a function of pressure die casting process parameters. The conclusion gives the analysis and the interpretation of the obtained

results.

A numerical model of binary alloy crystallization, based on the cellular automaton technique, is presented. The model allows to follow the

crystallization front movement and to generate the images of evolution of the dendritic structures during the solidification of a binary

alloy. The mathematic description of the model takes into account the proceeding thermal, diffusive, and surface phenomena. There are

presented the results of numerical simulations concerning the multi-dendritic growth of solid phase along with the accompanying changes

in the alloying element concentration field during the solidification of Al + 5% wt. Mg alloy. The model structure of the solidified casting

was achieved and compared with the actual structure of a die casting. The dendrite interaction was studied with respect to its influence on

the generation and growth of the primary and secondary dendrite arms and on the evolution of solute segregation both in the liquid and in

the solid state during the crystallization of the examined alloy. The morphology of a single, free-growing dendritic crystal was also

modelled. The performed investigations and analyses allowed to state e.g. that the developed numerical model correctly describes the

actual evolution of the dendritic structure under the non-equilibrium conditions and provides for obtaining the qualitatively correct results

of simulation of the crystallization process.

The paper reports the results of a physical modelling study of the production of a hypereutectic aluminium alloy to be used for making an alloy vapour source for operation in the magnetron. Within the study, targets from a hypereutectic aluminium-silicon alloy were made in laboratory conditions. Thus obtained material was subjected to heat treatment, porosity analysis, and the assessment of the microstructure and fitness for being used in the magnetron. The process of melting the hypereutectic Al-Si alloy was carried out at the Department of Foundry of the Czestochowa University of Technology. The investigation into the production of the alloy vapour source for the synthesis of the dielectric material from the hypereutectic aluminium alloy has confirmed.

The work presents the investigation results concerning the structure of composite pressure die castings with AlSi11 alloy matrix reinforced

with SiC particles. Examination has been held for composites containing 10 and 20 volume percent of SiC particles. The arrangement of

the reinforcing particles within the matrix has been qualitatively assessed in specimens cut out of the castings. The index of distribution

was determined on the basis of particle count in elementary measuring fields. The tensile strength, the yield point and elongation of the

obtained composite were measured. Composite castings were produced at various values of the piston velocity in the second stage of

injection, diverse intensification pressure values, and various injection gate width values. The regression equation describing the change of

the considered arrangement particles index and mechanical properties were found as a function of the pressure die casting parameters. The

infuence of particle arrangement in composite matrix on mechanical properties these material was examined and the functions of

correlations between values were obtained. The conclusion gives the analysis and the interpretation of the obtained results.

The paper, which is a summary and supplement of previous works and research, presents the results of numerical and physical modeling of the GX2CrNiMoCuN25-6-3 duplex cast steel thin-walled castings production. To obtain thin-walled castings with wall in the thinnest place even below 1 mm was used the centrifugal casting technology and gravity casting. The analyzed technology (centrifugal casting) enables making elements with high surface quality with reduced consumption of batch materials and, as a result, reducing the costs of making a unitary casting. The idea behind the production of cast steel with the use of centrifugal technology was to find a remedy for the problems associated with unsatisfactory castability of the tested alloy.

The technological evaluation of the cast construction was carried out using the Nova Flow & Solid CV 4.3r8 software. Numerical simulations of crystallization and cooling were carried out for a casting without a gating system and sinkhead located in a mold in accordance with the pouring position. It was assumed that the analyzed cast will be made in the sand form with dimensions 250×250×120 mm.