Archives of Foundry Engineering

Casting is the most widely used manufacturing technique. Furan No-bake mould system is very widely accepted in competitive foundry

industries due to its excellent characteristics of producing heavy and extremely difficult castings. These castings have excellent surface

finish and high dimensional stability. Self setting and high dimensional stability are the key characteristics of FNB mould system which

leads to reduce production cycle time for foundry industries which will ultimately save machining cost, labour cost and energy.

Compressive strength is the main aspect of furan no bake mould, which can be improved by analyzing the effect of various parameters on

it. ANN is a useful technique for determining the relation of various parameters like Grain Fineness Number, Loss on Ignition, pH, % resin

and temperature of sand with compressive strength of the FNB mould. Matlab version: R2015a version 8.3 software with ANN tool box

can be used to gain output of relation. This paper deals with the representation of relationship of various parameters affecting on the

compressive strength of FNB mould

The purpose of this study was to establish a relationship between the type of wall connection used in the cast grates, which are part of the

equipment operating in furnaces for heat treatment and thermal-chemical treatment, and stresses generated in these grates during the

process of rapid cooling. The places where the grate walls are connected to each other are usually characterized by the thickness larger

than the remaining parts of walls. Temperature variations in those places are responsible for the formation of hot spots, and in the hot spots

temperature changes much more slowly. The type of wall connection shapes the temperature gradient in the joint cross-section, and hence

also the value of thermal stresses generated during cooling. In this study, five different designs of the grates were compared; the difference

in them was the type of the designed wall connection. The following design variants were adopted in the studies: X connections with and

without holes, T connections with and without technological recesses, and R (ring) connection. Numerical analysis was performed to

examine how the distribution of temperature changes in the initial phases of the cooling process. The obtained results served next as a tool

in studies of the stress distribution in individual structures. The analysis were carried out by FEM in Midas NFX 2014 software. Based on

the results obtained, the conclusions were drawn about the impact of different types of wall connections on the formation of thermal

stresses in cast grates.

The most important feature of bells is their sound. Its clarity and beauty depend, first of all, on the bell’s geometry - particularly the shape

of its profile, but also on the quality of alloy used to its cast. Hence, if the melting and pouring parameters could influence the alloy’s

properties, what influence they would have on the frequencies of bell’s tone. In the article authors present their own approaches to find

answers on that and more questions.

The surfacing technologies are used for constitution of protection layer against wear and is destined for obtaining coating with high

hardness. Among many weldings methods currently used to obtain the hard surface layer one of the most effective way of hardfacing is

using flux cored arc welding. This additional material gives more possibilities to make expected hard surface layer.

Chemical composition, property and economic factors obtained in flux cored wire are much richer in comparison to these obtained with

other additional materials. This is the reason why flux cored wires give possibilities of application this kind of material for improving

surface in different sectors of industry.

In the present paper the imperfection in the layers was used for hardfacing process in different situations to show the possible application

in the surface layer. The work presents studies of imperfection of the welds, contains the picture of microstructures, macrostructures and

shows the results of checking by visual and penetrant testing methods.

In this paper an attempt to determine the relationship between the electrical resistivity and the tensile strength and hardness of cast iron of

carbon equivalent in the range from 3.93% to 4.48%. Tests were performed on the gray cast iron for 12 different melts with different

chemical composition. From one melt poured 6 samples. Based on the study of mechanical and electro-resistive determined variation

characteristics of tensile strength, hardness and resistivity as a function of the carbon equivalent. Then, regression equations were

developed as power functions describing the relationship between the resistivity of castings and their tensile strength and hardness. It was

found a high level of regression equations to measuring points, particularly with regard to the relationship Rm=f(ρ). The obtained

preliminary results indicate the possibility of application of the method of the resistance to rapid diagnostic casts on the production line,

when we are dealing with repeatable production, in this case non variable geometry of the product for which it has been determinated

before a regression equation.

The article presents research results of physico-chemical and environmental issues for the dust generated during dedusting of the

installation for the processing and preparation of moulding sand with bentonite. Particular attention was paid to the content of heavy

metals and emission of gases from the BTEX group, which is one of the determinants of the moulding sands harmfulness for the

environment. The analysis of heavy metals in the test samples indicate that there is an increase of the content of all metals in the dust

compared to the initial mixture of bentonite. The most significant (almost double) increase observed for zinc is probably related to the

adsorption of this element on the dust surface by contact with the liquid metal. The study showed, that dust contained more than 20% of

the amount of montmorillonite and had a loss on ignition at a similar level. The addition of 1% of dust to the used moulding sand results in

almost 30% increase in the total volume of gases generated in casting processes and nearly 30% increase of the benzene emission.

This paper discusses the mechanical properties of a material fabricated from commercially available metal powder mixtures designed for

use as a metal matrix of diamond impregnated composites. The mixtures with the catalogue numbers CSA and CSA800 provided by a

Chinese producer are suitable for experimental laboratory testing. The specimens were fabricated in a graphite mould using hot pressing.

The material was tested for density, porosity, hardness, and tensile strength under static loading. A scanning electron microscope (SEM)

was used to analyze the microstructure and cleavage fracture of broken specimens. It was essential to determine how the chemical

composition and the fabrication process affected the microstructure and properties of the material. The properties of the sinters were

compared with those of hot pressed specimens fabricated from sub-micron size cobalt powder (Cobalt SMS). Although the as-consolidated

material is inferior to cobalt, it displays a favourable combination of hardness, yield strength and ductility, and seems to have a great

potential for moderate and general purpose applications.

The scope of work included the launch of the process of refining slag suspension in a gas oven using a variety of technological additives.

After the refining process (in the context of copper recovery), an assessment of the effect of selected reagents at the level of the slag

refining suspension (in terms of copper recovery). Method sieve separated from the slag waste fraction of metallic, iron - silicate and

powdery waste. Comparison of these photographs macroscopic allowed us to evaluate the most advantageous method of separating

metallic fraction from the slag. After applying the sample A (with KF2 + NaCl) we note that in some parts of the slag are still large

amounts of metallic fraction. The fraction of slag in a large majority of the elements has the same size of 1 mm, and a larger portion of the

slag, the size of which is from 2 to 6 mm. Definitely the best way is to remove the copper by means of the component B (with NaCl ) and

D (with KF2

). However, as a result of removing the copper by means of component C (with CaO) were also obtained a relatively large

number of tiny droplets of copper, which was problematic during segregation. In both cases we were able to separate the two fractions in a

fast and simple manner.

The dry sliding wear behavior of heat-treated super duplex stainless steel AISI 2507 was examined by taking pin-on-disc type of wear-test

rig. Independent parameters, namely applied load, sliding distance, and sliding speed, influence mainly the wear rate of super duplex

stainless steel. The said material was heat treated to a temperature of 850°C for 1 hour followed by water quenching. The heat treatment

was carried out to precipitate the secondary sigma phase formation. Experiments were conducted to study the influence of independent

parameters set at three factor levels using the L27 orthogonal array of the Taguchi experimental design on the wear rate. Statistical

significance of both individual and combined factor effects was determined for specific wear rate. Surface plots were drawn to explain the

behavior of independent variables on the measured wear rate. Statistically, the models were validated using the analysis of variance test.

Multiple non-linear regression equations were derived for wear rate expressed as non-linear functions of independent variables. Further,

the prediction accuracy of the developed regression equation was tested with the actual experiments. The independent parameters

responsible for the desired minimum wear rate were determined by using the desirability function approach. The worn-out surface

characteristics obtained for the minimum wear rate was examined using the scanning electron microscope. The desired smooth surface was

obtained for the determined optimal condition by desirability function approach.

The presence of the chunky graphite is unwanted in the cast iron with the spheroidal graphite for this significantly lowers the properties of

the ductile iron. This shape of the graphite is formed as the result of the slow cooling rate of the castings with large thermal point and also

due to the presence of the elements which suppress the formation of the spheroidal graphite and support formation of the chunky graphite.

The spheroidal graphite present in the ductile iron assures the excellent mechanical properties, while the chunky graphite significantly

reduces those properties of the ductile iron. Therefore it is of importance to assume conditions under which prevented is the formation of

the chunky graphite. The casts were carried out under the conditions of the regular operation of the foundry and tested were various types

of modifiers and inoculators and also pre-inoculators containing the elements suppressing the formation of the chunky graphite (Al, Sb a

Ba). Applied were also the chromium breaker core to suppress the formation chunky graphite which was present in the structure in the

places after the feeders elimination. As whole, executed were eight casts with various types of the modifiers and inoculators.

The paper presents results of the possibility of adapting the Althoff-Radtke test for High Chromium Cast Iron. The Althoff-Radtke test is a

clump attempt used for steel. The Althoff-Radtke test has four different lengths of clamp which qualifies it as a test to quantitatively take

into account different kinds of shrinkage ΔL. The length of the slot of the cracked corner and the length of each staple (50 - 350 mm) are

the parameters tendency to cast cracks. Castings of white cast iron have a high tendency to hot cracking due to the large range of

solidification temperatures, unfavorable kinetics parameters of shrinkage, and especially a lack of expansion before shrinkage. Shrinkage

of high chromium white cast iron is similar to the shrinkage of cast steel, and is approximately 2%. Therefore it is important to test

susceptibility to hot cracks. Research was carried out under industrial conditions. Four melts were performed, one of the initial chemical

composition and the other three modified by different amounts of Fe-Ti, respectively, 0.25%, 0.5% and 0.75% Fe-Ti. The propensity for

hot cracking was based on the observation of the dark surface in the corner of the sample. The study shows that the Althoff-Radtke test can

be adapted to determine the tendency for hot cracking of high chromium cast iron. It should however be noted that the test results cannot be

compared with those for other alloys.

The publication presents the results of examination of selected carburizers used for cast iron production with respect to their electric

resistance. Both the synthetic graphite carburizers and petroleum coke (petcoke) carburizers of various chemical composition were

compared. The relationships between electrical resistance of tested carburizers and their quality were found. The graphite carburizers

exhibited much better conductivity than the petcoke ones. Resistance characteristics were different for the different types of carburizers.

The measurements were performed according to the authors’ own method based on recording the electric current flow through the

compressed samples. The samples of the specified diameter were put under pressure of the gradually increased value (10, 20, 50, 60, and

finally 70 bar), each time the corresponding value of electric resistance being measured with a gauge of high accuracy, equal to 0.1μΩ.

The higher pressure values resulted in the lower values of resistance. The relation between both the thermal conductance and the electrical

conductance (or the resistance) is well known and mentioned in the professional literature. The results were analysed and presented both in

tabular and, additionally, in graphic form.

The results of investigations of spent moulding sands taken from the mould at various distances from the surface of the produced casting,

are presented in the paper. The casting mould was made with an application of the cooling system of the metal core in order to increase the

cooling rate of the ladle casting. As temperature measurements in the mould indicated the heat flow from the metal did not create

conditions for the complete burning of a moulding sand. The analysis was performed to find out changes of spent moulding sands caused

by degradation and destruction processes of organic binders. Conditions occurring in the casting mould were discussed on the bases of

testing: ignition losses, dusts contents, pH reactions and the surface morphology of the moulding sand samples. Factors limiting the

effective mould degassing were pointed out. Operations, possible for realization, which can limit the reasons of a periodical occurrence of

increased amounts of casting defects due to changing gas evolution rates being the result of the technological process, were also indicated.

Growing emission requirements are forcing the foundry industry to seek new, more environmentally friendly solutions. One of the

solutions may be the technologies of preparing moulding and core sands using organic biodegradable materials

as binders. However, not only environmental requirements grow but also those related to the technological properties

of moulding sand. Advancing automation and mechanization of the foundry industry brings new challenges related to the moulding sands.

Low elasticity may cause defects during assembly of cores or moulds by the manipulators.

The paper presents the study of flexibility in the room temperature according to new method and resistance to thermal deformation of selfhardening

moulding sands with furfuryl resin, containing biodegradable material PCL. The task of the new additive is to reduce the

moulding sands harmfulness to the environment and increase its flexibility in the room temperature. The impact of the additive and the

effect of the amount of binder on the properties of mentioned moulding sands were analysed. Studies have shown that the use of 5% of

PCL does not change the nature of the thermal deformation curve, improves the bending strength of tested moulding mixtures and

increases their flexibility at room temperature.

The new investigation method of the kinetics of the gas emission from moulding sands used for moulds and cores is presented in this

paper. The gas evolution rate is presented not only as a function of heating time but also as a function of instantaneous temperatures. In

relation to the time and heating temperature the oxygen and hydrogen contents in evolving gases was also measured. This method was

developed in the Laboratory of Foundry Moulds Technology, Faculty of Foundry Engineering, AGH. Gas amounts which are emitted from

the moulding sand at the given temperature recalculated to the time unit (kinetics) are obtained in investigations. Results of investigations

of moulding sand with furan resin are presented - as an example - in the paper.

Heating process in the domain of thin metal film subjected to a strong laser pulse are discussed. The mathematical model of the process

considered is based on the dual-phase-lag equation (DPLE) which results from the generalized form of the Fourier law. This approach is,

first of all, used in the case of micro-scale heat transfer problems (the extremely short duration, extreme temperature gradients and very

small geometrical dimensions of the domain considered). The external heating (a laser action) is substituted by the introduction of internal

heat source to the DPLE. To model the melting process in domain of pure metal (chromium) the approach basing on the artificial mushy

zone introduction is used and the main goal of investigation is the verification of influence of the artificial mushy zone ‘width’ on the

results of melting modeling. At the stage of numerical modeling the author’s version of the Control Volume Method is used. In the final

part of the paper the examples of computations and conclusions are presented.

Development of open cellular metal foam technology based on investment casting applying the polyurethane pattern is discussed.

Technological process comprises preparing of the ceramic mold applying PUR foam as the pattern, firing of the mold, pouring of the

liquid Zn-Al alloy into the mold and washing out of the ceramic material from cellular casting. Critical parameters such as the temperature

of mold and poured metal, design of gating system affected by metalostatic pressure allowed to produce castings with cellular structure

characterized by the open porosity.

Metal cellular foams with the open porosity embedded in phase change material (PCM) enhance heat transfer and reduce time operations

in energy storage systems. Charging and discharging were performed at the laboratory accumulator by heating and cooling with flowing

water characterized by the temperatures of 97-100oC. Temperature measurements were collected from 7 different thermocouples located

in the accumulator. In relation to the tests with pure paraffin, embedding of the metal Zn-Al cellular foam in paraffin significantly

decreases temperature gradients and melting time of paraffin applied as PCM characterized by the low thermal conductivity. Similarly,

reduction of discharging time by this method improves the efficiency of thermal energy storage system applied in solar power plants or for

the systems of energy efficient buildings.

Very well-known advantages of aluminum alloys, such as low mass, good mechanical properties, corrosion resistance, machining-ability,

high recycling potential and low cost are considered as a driving force for their development, i.e. implementation in new applications as

early as in stage of structural design, as well as in development of new technological solutions. Mechanical and technological properties of

the castings made from the 3xx.x group of alloys depend mainly on correctly performed processes of melting and casting, design of a

mould and cast element, and a possible heat treatment.

The subject-matter of this paper is elaboration of a diagrams and dependencies between parameters of dispersion hardening (temperatures

and times of solutioning and ageing treatments) and mechanical properties obtained after heat treatment of the 356.0 (EN AC AlSi7Mg)

alloy, enabling full control of dispersion hardening process to programming and obtaining a certain technological quality of the alloy in

terms of its mechanical properties after performed heat treatments. Obtained results of the investigations have enabled obtainment of a

dependencies depicting effect of parameters of the solutioning and ageing treatments on the mechanical properties (Rm, A5 and KC impact

strength) of the investigated alloy. Spatial diagrams elaborated on the basis of these dependencies enable us to determine tendencies of

changes of the mechanical properties of the 356.0 alloy in complete analyzed range of temperature and duration of the solutioning and

ageing operations.

Statistical Process Control (SPC) based on the Shewhart’s type control charts, is widely used in contemporary manufacturing industry,

including many foundries. The main steps include process monitoring, detection the out-of-control signals, identification and removal of

their causes. Finding the root causes of the process faults is often a difficult task and can be supported by various tools, including datadriven

mathematical models. In the present paper a novel approach to statistical control of ductile iron melting process is proposed. It is

aimed at development of methodologies suitable for effective finding the causes of the out-of-control signals in the process outputs,

defined as ultimate tensile strength (Rm) and elongation (A5), based mainly on chemical composition of the alloy. The methodologies are

tested and presented using several real foundry data sets. First, correlations between standard abnormal output patterns (i.e. out-of-control

signals) and corresponding inputs patterns are found, basing on the detection of similar patterns and similar shapes of the run charts of the

chemical elements contents. It was found that in a significant number of cases there was no clear indication of the correlation, which can

be attributed either to the complex, simultaneous action of several chemical elements or to the causes related to other process variables,

including melting, inoculation, spheroidization and pouring parameters as well as the human errors. A conception of the methodology

based on simulation of the process using advanced input - output regression modelling is presented. The preliminary tests have showed

that it can be a useful tool in the process control and is worth further development. The results obtained in the present study may not only

be applied to the ductile iron process but they can be also utilized in statistical quality control of a wide range of different discrete

processes.

With the use of differential scanning calorimetry (DSC), the characteristic temperatures and enthalpy of phase transformations were

defined for commercial AlSi9Cu3 cast alloy (EN AC-46000) that is being used for example for pressurized castings for automotive

industry. During the heating with the speed of 10oCmin-1

two endothermic effects has been observed. The first appears at the temperature

between 495 oC and 534 oC, and the other between 555 oC and 631 oC. With these reactions the phase transformation enthalpy comes up as

+6 J g-1

and +327 J g-1

. During the cooling with the same speed, three endothermic reactions were observed at the temperatures between

584 oC and 471 oC. The total enthalpy of the transitions is – 348 J g-1

.

Complimentary to the calorimetric research, the structural tests (SEM and EDX) were conducted on light microscope Reichert and on

scanning microscope Hitachi S-4200. As it comes out of that, there are dendrites in the structure of α(Al) solution, as well as the eutectic

(β) silicon crystals, and two types of eutectic mixture: double eutectic α(Al)+β(Si) and compound eutectic α+Al2Cu+β.

The development of a novel design for the toothed segment of drive transmission in longwall shearer is expected to significantly reduce

the cost of individual components of the feed system and the related work of repair and renovations, increasing at the same time the safety

of mine repair teams.

The conducted experimental and numerical analysis of the state of stress and strain in the innovative design of the toothed segment has

enabled estimating the maximum effort of the developed structure. Based on the results of fundamental mechanical studies of the cast

L20HGSNM steel and fatigue tests combined with the numerical stress/strain analysis, the fatigue life curve was plotted for the examined

casting of the rack.

For the die casting conditions of aluminium bronzes assumed based on the literature data, a thick-walled bush was cast, made of complex

aluminium bronze (Cu-Al-Fe-Ni-Cr). After the cast was removed from the mould, cracks were observed inside it. In order to identify the

stage in the technological production process at which, potentially, the formation of stresses damaging the continuity of the microstructure

created in the cast was possible (hot cracking and/or cold cracking), a computer simulation was performed. The article presents the results

of the computer simulation of the process of casting the material into the gravity die as well as solidifying and cooling of the cast in the

shape of a thick-walled bush. The simulation was performed with the use of the MAGMA5 program and by application of the

CuAl10Ni5,5Fe4,5 alloy from the MAGMA5 program database. The results were compared with the location of the defects identified in

the actual cast. As a result of the simulation of the die-casting process of this bush, potential regions were identified where significant

principal stresses accumulate, which can cause local hot and cold cracking. Until now, no research has been made of die-cast aluminium

bronzes with a Cr addition. Correlating the results of the computer simulation validated by the analysis of the actual cast made it possible

to clearly determine the critical regions in the cast exposed to cracking and point to the causes of its occurrence. Proposals of changes in

the bush die casting process were elaborated, in order to avoid hot tearing and cold cracking. The article discusses the results of

preliminary tests being a prologue to the optimization of the die-casting process parameters of complex aluminium bronze thick-walled

bushs.

The purpose of this paper was testing suitability of the time-series analysis for quality control of the continuous steel casting process in

production conditions. The analysis was carried out on industrial data collected in one of Polish steel plants. The production data

concerned defective fractions of billets obtained in the process. The procedure of the industrial data preparation is presented. The

computations for the time-series analysis were carried out in two ways, both using the authors’ own software. The first one, applied to the

real numbers type of the data has a wide range of capabilities, including not only prediction of the future values but also detection of

important periodicity in data. In the second approach the data were assumed in a binary (categorical) form, i.e. the every heat(melt) was

labeled as ‘Good’ or ‘Defective’. The naïve Bayesian classifier was used for predicting the successive values. The most interesting results

of the analysis include good prediction accuracies obtained by both methodologies, the crucial influence of the last preceding point on the

predicted result for the real data time-series analysis as well as obtaining an information about the type of misclassification for binary data.

The possibility of prediction of the future values can be used by engineering or operational staff with an expert knowledge to decrease

fraction of defective products by taking appropriate action when the forthcoming period is identified as critical.

The results of structure and mechanical properties investigations of tungsten heavy alloy (THA) after cyclic sintering are presented. The

material for study was prepared using liquid phase sintering of mixed and compacted powders in hydrogen atmosphere. The specimens in

shape of rods were subjected to different number of sintering cycles according to the heating schemes given in the main part of the paper

From the specimens the samples for mechanical testing and structure investigations were prepared. It follows from the results of the

mechanical studies, that increasing of sintering cycles lead to decrease of tensile strength and elongation of THA with either small or no

influence on yield strength. In opposite to that, the microstructure observations showed that the size of tungsten grain increases with

number of sintering cycles. Moreover, scanning electron microscope (SEM) observations revealed distinctly more trans-granular cleavage

mode of fracture in specimens subjected to large number of sintering cycles compared with that after one or two cycles only.

The lifetime of guide grates in pusher furnaces for heat treatment could be increased by raising the flexibility of their structure through, for

example, the replacement of straight ribs, parallel to the direction of grate movement, with more flexible segments. The deformability of

grates with flexible segments arranged in two orientations, i.e. crosswise (perpendicular to the direction of compression) and lengthwise

(parallel to the direction of compression), was examined. The compression process was simulated using SolidWorks Simulation program.

Relevant regression equations were also derived describing the dependence of force inducing the grate deformation by 0.25 mm ‒ modulus

of grate elasticity ‒ on the number of flexible segments in established orientations. These calculations were made in Statistica and Scilab

programs. It has been demonstrated that, with the same number of segments, the crosswise orientation of flexible segments increases the

grate structure flexibility in a more efficient way than the lengthwise orientation. It has also been proved that a crucial effect on the grate

flexibility has only the quantity and orientation of segments (crosswise / lengthwise), while the exact position of segments changes the

grate flexibility by less than 1%.

The work presents results of investigations concerning the production of cast iron containing about 5-6% aluminium, with the ferritic

matrix in the as-cast state and nodular or vermicular graphite precipitates. The examined cast iron came from six melts produced under the

laboratory conditions. It contained aluminium in the amount of 5.15% to 6.02% (carbon in the amount of 2.41% to 2.87%, silicon in the

amount of 4.50% to 5.30%, and manganese in the amount of 0.12% to 0.14%). After its treatment with cerium mixture and graphitization

with ferrosilicon (75% Si), only nodular and vermicular graphite precipitates were achieved in the examined cast iron. Moreover, it is

possible to achieve the alloy of pure ferritic matrix, even after the spheroidizing treatment, when both the aluminium and the silicon occur

in cast iron in amounts of about 5.2÷5.3%.

In the paper, a research on effects of baking temperature on chromite sand base of moulding sands bonded with sodium silicate is

presented. Pure chromite sand and its chromite-based moulding sand prepared with use of sodium silicate were subjected to heating within

100 to 1200 °C. After cooling-down, changes of base grains under thermal action were determined. Chromite moulding sand was prepared

with use of 0.5 wt% of domestic made, unmodified sodium silicate (water-glass) grade 145. After baking at elevated temperatures, creation

of rough layer was observed on grain surfaces, of both pure chromite sand and that used as base of a moulding sand. Changes of sand

grains were evaluated by scanning microscopy and EDS analyses. It was found that changes on grain surfaces are of laminar nature. The

observed layer is composed of iron oxide (II) that is one of main structural components of chromite sand. In order to identify changes in

internal structure of chromite sand grains, polished sections were prepared of moulding sand hardened with microwaves and baked at

elevated temperatures. Microscopic observations revealed changes in grains structure in form of characteristically crystallised acicular

particles with limited magnesium content, intersecting at various angles. EDS analysis showed that these particles are composed mostly of

chromium oxide (III) and iron oxide (II). The temperature above that the a.m. changes are observed in both chromite-based moulding sand

and in pure chromite sand. The observed phenomena were linked with hardness values and mass of this sand.

In the high-alloy, ferritic - austenitic (duplex) stainless steels high tendency to cracking, mainly hot-is induced by micro segregation

processes and change of crystallization mechanism in its final stage. The article is a continuation of the problems presented in earlier

papers [1 - 4]. In the range of high temperature cracking appear one mechanism a decohesion - intergranular however, depending on the

chemical composition of the steel, various structural factors decide of the occurrence of hot cracking. The low-carbon and low-alloy cast

steel casting hot cracking cause are type II sulphide, in high carbon tool cast steel secondary cementite mesh and / or ledeburite segregated

at the grain solidified grains boundaries, in the case of Hadfield steel phosphorus - carbide eutectic, which carrier is iron-manganese and

low solubility of phosphorus in high manganese matrix. In duplex cast steel the additional factor increasing the risk of cracking it is very

"rich" chemical composition and related with it processes of precipitation of many secondary phases.

Design of gating system is an important factor in obtaining defect-free casting. One of the casting defects is a porosity caused by internal

shrinkage in solidification process. Prediction of the internal shrinkage porosity in the femoral stem of commercially pure titanium (CP-Ti)

is investigated based on the gating system design. The objective of this research is to get the best gating system between three gating

system designs. Three gating system designs of the femoral stem were simulated in an investment casting method. The internal shrinkage

porosity occurs on the largest part and near the ingate of the femoral stem. The gating system design that has ingates cross section area:

78.5; 157; and 128.5 mm2

has the least of the internal shrinkage porosity. This design has the most uniform solidification in the entire of

the femoral stem. An experiment is conducted to validate the simulation data. The results of internal shrinkage porosity in the three gating

system designs in the simulation were compared with the experiment. Based on the comparison, the trend of internal shrinkage porosity at

the three gating system designs in the simulation agrees with the experiment. The results of this study will aid in the elimination of casting

defect.

Widely used in the power and mining industry, cast Hadfield steel is resistant to wear, but only when operating under impact loads.

Components made from this alloy exposed to the effect of abrasion under load-free conditions are known to suffer rapid and premature

wear. To increase the abrasion resistance of cast high-manganese steel under the conditions where no dynamic loads are operating, primary

titanium carbides are formed in the process of cast steel melting, to obtain in the alloy after solidification and heat treatment, the

microstructure composed of very hard primary carbides uniformly distributed in the austenitic matrix of a hardness superior to the

hardness of common cast Hadfield steel. Hard titanium carbides ultimately improve the wear resistance of components operating under

shear conditions. The measured microhardness of the as-cast matrix in samples tested was observed to increase with the increasing content

of titanium and was 380 HV0.02 for the content of 0.4%, 410 HV0.02 for the content of 1.5% and 510 HV0.02 for the content of 2 and

2.5%. After solution heat treatment, the microhardness of the matrix was 460÷480 HV0.02 for melts T2, T3 and T6, and 580 HV0.02 for

melt T4, and was higher than the values obtained in common cast Hadfield steel (370 HV0.02 in as-cast state and 340÷370 HV0.02 after

solution heat treatment). The measured microhardness of alloyed cementite was 1030÷1270 HV0.02; the microhardness of carbides

reached even 2650÷4000 HV0.02.

In a vacuum Bridgman-type furnace, under an argon atmosphere, directionally solidified sample of Fe - C alloy was produced. The pulling

rate was v = 83 μm/s (300 mm/h) and constant temperature gradient G = 33,5 K/mm. The microstructure of the sample was examined on

the longitudinal section using an Optical Microscope and Scanning Electron Microscope. The X-ray diffraction and electron backscatter

diffraction technique (EBSD) have been used for the crystallographic analysis of carbide particles in carbide eutectic. The

X-ray diffraction was made parallel and perpendicular to the axis of the goniometer. The EBSD shows the existence of iron carbide Fe3C

with orthorhombic and hexagonal structure. Rapid solidification may cause a deformation of the lattice plane which is indicated by

different values of the lattice parameters. Such deformation could also be the result of directional solidification. Not all of the peaks in

X–ray diffractograms were identified. They may come from other iron carbides. These unrecognized peaks may also be a result of the

residual impurity of alloy.

The work is a continuation of research concerning the influence of intensive cooling of permanent mold in order to increase the casting

efficiency of aluminium alloys using the multipoint water mist cooling system. The paper presents results of investigation of crystallization

process and microstructure of synthetic hypereutectic alloys: AlSi15 and AlSi19. Casts were made in permanent mold cooled with water

mist stream. The study was conducted for unmodified silumins on the research station allowing the cooling of the special permanent probe

using a program of computer control. Furthermore the study used a thermal imaging camera to analyze the solidification process of

hypereutectic silumins. The study demonstrated that the use of mold cooled with water mist stream allows in wide range the formation of

the microstructure of hypereutectic silumins. It leads to higher homogeneity of microstructure and refinement of crystallizing phases and

also it increases subsequently the mechanical properties of casting.

Oxygen is an element that is first purposely brought into the steel melt to remove some unwanted elements or to reduce their concentration

(oxidation). In the made cast steel there is on the contrary necessary to reduce the oxygen content with the use of deoxidation to such a

level in order to avoid a reaction with carbon with the formation of CO bubbles. Concentration of oxygen in steel before casting is given,

in particular, by the manner of metallurgical processing and the used deoxidation process. Oxygen is found in molten steels both as

chemically bound in the form of oxides and in the form of oxygen dissolved in the solution – the melt. Chemical composition

of the melt strongly influences the activity of oxygen dissolved in the melt and further on the composition of oxidic inclusions forming in

the melt during the reaction with oxygen. In the Fe-C-Cr-Ni based alloys in the reaction with oxygen greatly participates also chrome,

whose products are often in solid state and they are the cause of forming such defects as e.g. oxidic films.

No-bake process refers to the use of chemical binders to bond the moulding sand. Sand is moved to the mould fill station in preparation for

filling of the mould. A mixer is used to blend the sand with the chemical binder and activator. As the sand exits the mixer, the binder

begins the chemical process of hardening. This paper presents the results of decomposition of the moulding sands with modified ureafurfuryl

resin (with the low content of furfuryl alcohol below 25 % and different activators: organic and inorganic) on a quartz matrix,

under semi-industrial conditions. Investigations of the gases emission in the test foundry plant were executed according to the method

extended in the Faculty of Foundry Engineering (AGH University of Science and Technology). Article presents the results of the emitted

chosen aromatic hydrocarbons and loss on ignition compared with the different activators used to harden this resin. On the bases of the

data, it is possible to determine the content of the emitted dangerous substances from the moulding sand according to the content of loss on

ignition.

The aim of the hereby paper is to present the developed model of determining the volume and surface porosity based on the main fraction

of polifractional materials, its experimental verification and utilisation for the interpretation of effects accompanying the formation of a

moulding sand apparent density, porosity and permeability in the blowing processes of the core and moulds technology.

The paper concerns evaluation of the coefficient of friction characterising a friction couple comprising a commercial brake disc cast of

flake graphite grey iron and a typical brake pad for passenger motor car. For the applied interaction conditions, the brake pressure of

0.53 MPa and the linear velocity measured on the pad-disc trace axis equalling 15 km/h, evolution of the friction coefficient μ values were

observed. It turned out that after a period of 50 minutes, temperature reached the value 270°C and got stabilised. After this time interval,

the friction coefficient value also got stabilised on the level of μ = 0.38. In case of a block in its original state, stabilisation of the friction

coefficient value occurred after a stage in the course of which a continuous growth of its value was observed up to the level μ = 0.41 and

then a decrease to the value μ = 0.38. It can be assumed that occurrence of this stage was an effect of an initial running-in of the friction

couple. In consecutive abrasion tests on the same friction couple, the friction coefficient value stabilisation occurred after the stage of

a steady increase of its value. It can be stated that the stage corresponded to a secondary running-in of the friction couple. The observed

stages lasted for similar periods of time and ended with reaching the stabile level of temperature of the disc-pad contact surface.

The article presents the results of a comparative analysis of the metal substructure for dental prosthesis made from a Co-Cr-Mo-W alloy by

two techniques, i.e. precision investment casting and selective laser melting (SLM). It was found that the roughness of the raw surface of

the SLM sinter is higher than the roughness of the cast surface, which is compensated by the process of blast cleaning during metal

preparation for the application of a layer of porcelain. Castings have a dendritic structure, while SLM sinters are characterized by a

compact, fine-grain microstructure of the hardness higher by about 100 HV units. High performance and high costs of implementation the

SLM technology are the cause to use it for the purpose of many dental manufacturers under outsourcing rules. The result is a reduction in

manufacturing costs of the product associated with dental work time necessary to scan, designing and treatment of sinter compared with

the time needed to develop a substructure in wax, absorption in the refractory mass, casting, sand blasting and finishing. As a result of

market competition and low cost of materials, sinter costs decrease which brings the total costs related to the construction unit making

using the traditional method of casting, at far less commitment of time and greater predictability and consistent sinter quality.

Investigation of the tensile and fatigue properties of cast magnesium alloys, created by the heated mold continuous casting process (HMC),

was conducted. The mechanical properties of the Mg-HMC alloys were overall higher than those for the Mg alloys, made by the

conventional gravity casting process (GC), and especially excellent mechanical properties were obtained for the Mg97Y2Zn1

-HMC alloy.

This was because of the fine-grained structure composed of the -Mg phases with the interdendritic LPSO phase. Such mechanical

properties were similar levels to those for conventional cast aluminum alloy (Al84.7Si10.5Cu2.5Fe1.3Zn1 alloys: ADC12), made by the GC

process. Moreover, the tensile properties (UTS and f

) and fatigue properties of the Mg97Y2Zn1

-HMC alloy were about 1.5 times higher

than that for the commercial Mg90Al9Zn1

-GC alloy (AZ91). The high correlation rate between tensile properties and fatigue strength

(endurance limit: l

) was obtained. With newly proposed etching technique, the residual stress in the Mg97Y2Zn1 alloy could be revealed,

and it appeared that the high internal stress was severely accumulated in and around the long-period stacking-order phases (LPSO). This

was made during the solidification process due to the different shrinkage rate between α-Mg and LPSO. In this etching technique, microcracks

were observed on the sample surface, and amount of micro-cracks (density) could be a parameter to determine the severity of the

internal stress, i.e., a large amount to micro-cracks is caused by the high internal stress.

Paper present a thermal analysis of laser heating and remelting of EN AC-48000 (EN AC-AlSi12CuNiMg) cast alloy used mainly for

casting pistons of internal combustion engines. Laser optics were arranged such that the impingement spot size on the material was a

circular with beam radius rb changes from 7 to 1500 m. The laser surface remelting was performed under argon flow. The resulting

temperature distribution, cooling rate distribution, temperature gradients and the depth of remelting are related to the laser power density

and scanning velocity. The formation of microstructure during solidification after laser surface remelting of tested alloy was explained.

Laser treatment of alloy tests were perform by changing the three parameters: the power of the laser beam, radius and crystallization rate.

The laser surface remelting needs the selection such selection of the parameters, which leads to a significant disintegration of the structure.

This method is able to increase surface hardness, for example in layered castings used for pistons in automotive engines.

The paper presents results of metallographic examination of faults occurring in the course of founding thin-walled cast-iron castings in

furan resin sand molds. A non-conformance of the scab type was Observed on surface of the casting as well as sand buckles and cold

shots. Studied the chemical composition by means of a scanning electron microscope in a region of casting defects: microanalysis point

and microanalysis surface. Around the observed defects discloses high concentration of oxides of iron, manganese and silicon.

A computer simulation of the casting process has been carried out with the objective to establish the cause of occurrence of cold shots on

casting surface. The simulation was carried out with the use of NovaFlow & Solid program. We analyzed the flowing metal in the mold

cavity. The main reason for the occurrence of casting defects on the surface of the casting was gating system, which caused turbulent flow

of metal with a distinctive splash stream of liquid alloy.