Archives of Foundry Engineering

The present work focuses on the modeling and analysis of mechanical properties of structural steel. The effect of major alloying elements

namely carbon, manganese and silicon has been investigated on mechanical properties of structural steel. Design of experiments is used to

develop linear models for the responses namely Yield strength, Ultimate tensile strength and Elongation. The experiments have been

conducted as per the full factorial design where all process variables are set at two levels. The main effect plots showed that the alloying

elements Manganese and Silicon have positive contribution on Ultimate tensile strength and Yield strength. However, Carbon and

Manganese showed more contribution as compared to Silicon. All three alloying elements are found to have negative contribution

towards the response- Elongation. The present work is found to be useful to control the mechanical properties of structural steel by varying

the major alloying elements. Minitab software has been used for statistical analysis. The linear regression models have been tested for the

statistical adequacy by utilizing ANOVA and statistical significance test. Further, the prediction capability of the developed models is

tested with the help of test cases. It is found that all linear regression models are found to be statistically adequate with good prediction

capability. The work is useful to foundrymen to choose alloying elements composition to get desirable mechanical properties.

The paper presents the results of research on the determination of the effect of pouring temperature on the macrostructure of the castings

subjected to complex (surface and volume) modification and double filtration. Tested castings were made of post-production scrap (gating

system parts) of IN-713C superalloy. Tests included the evaluation of the number of grains per 1 mm2

, mean grain surface area, shape

factor and tensile strength. Casting temperature below 1470 °C positively influenced the modification effect. The grains were finer and the

mechanical properties increased, especially for castings with thicker walls. On the other hand, manufacture of thin walled castings of high

quality require pouring temperature above 1480 °C.

Paper presents the assessment of impact of heat treatment on durability in low-cycle fatigue conditions (under constant load) in castings

made using post-production scrap of MAR-247 and IN-713C superalloys. Castings were obtained using modification and filtration

methods. Additionally, casting made of MAR-247 were subjected to heat treatment consisting of solution treatment and subsequent aging.

During low-cycle fatigue test the cyclic creep process were observed. It was demonstrated that the fine-grained samples have significantly

higher durability in test conditions and , at the same time, lower values of plastic deformation to rupture Δϵpl. It has been also proven that

durability of fine-grained MAR-247 samples can be further raised by about 60% using aforementioned heat treatment.

Experiments of filling the model moulds cavity of various inner shapes inserted in rectangular cavity of the casting die (dimensions: 280

mm (height) x 190 mm (width) x 10 mm (depth) by applying model liquids of various density and viscosity are presented in the paper.

Influence of die venting as well as inlet system area and inlet velocity on the volumetric rate of filling of the model liquid – achieved by

means of filming the process in the system of a cold-chamber casting die was tested. Experiments compared with the results of simulation

performed by means of the calculation module Novacast (Novaflow&Solid) for the selected various casting conditions – are also

presented in the paper.

The article shows the influence of environment requirements on changes in different foundry moulding sands technologies such as cold

box, self-hardening moulding sands and green sands. The aim of the article is to show the possibility of using the biodegradable materials

as binders (or parts of binders’ compositions) for foundry moulding and core sands. The authors concentrated on the possibility of

preparing new binders consisting of typical synthetic resins - commonly used in foundry practice - and biodegradable materials. According

to own research it is presumed that using biodegradable materials as a part of new binders’ compositions may cause not only lower toxicity

and better ability to reclaim, but may also accelerate the biodegradation rate of used binders. What’s more, using some kinds of

biodegradable materials may improve flexibility of moulding sands with polymeric binder. The conducted research was introductory and

took into account bending strength and thermal properties of furan moulding sands with biodegradable material (PCL). The research

proved that new biodegradable additive did not decrease the tested properties.

The problem considered in the paper is motivated by production planning in a foundry equipped with a furnace and a casting line,

which provides a variety of castings in various grades of cast iron/steel for a large number of customers. The goal is to create the order of

the melted metal loads to prevent delays in delivery of goods to customers. This problem is generally considered as a lot-sizing and

scheduling problem. However, contrary to the classic approach, we assumed the fuzzy nature of the demand set for a given day. The paper

describes a genetic algorithm adapted to take into account the fuzzy parameters of simultaneous grouping and scheduling tasks and

presents the results achieved by the algorithm for example test problem.

The problem related to the management of post reclamation dusts generated in the reclamation process of waste moulding sands with

organic binders is presented in the hereby paper. Waste materials generated in this process are products hazardous for the environment and

should be utilised. The prototype stand for the utilisation of this dangerous material in its co-burning with coal was developed and patented

in AGH in Krakow. The stand was installed in one of the domestic casting houses. As the utilisation result the transformed waste product

is obtained and its management in the production of ceramic materials constitutes the subject of the presented publication.

The validation of each simulation code used in foundry domain requires individual approach due to its specificity. This validation can by

elaborated on the basis of experimental results or in particular cases by comparison the simulation results from different codes. The article

concerns the influence of grey cast iron density curve and different forms of solid fraction curve Fs=f(T) on the formation of shrinkage

discontinuities. Solid fraction curves applying Newtonian Thermal Analysis (NTA) were estimated. The experimental and numerical

simulation tests were performed on the castings, which were made with Derivative Thermal Analysis (DerTA) standard cups. The

numerical tests were realized using NovaFlow&Solid (NF&S), ProCast and Vulcan codes. In this work, the coupled influence of both

curves on the dynamics of the shrinkage-expansion phenomena and on shrinkage defects prognosis in grey cast iron castings has been

revealed. The final evaluation of the simulation systems usefulness should be based on validation experiment, preceded by comparing the

simulation results of available systems which are proposed in given technology.

The results of structure observations of Ni base superalloy subjected to long-term influence of high pressure hydrogen atmosphere at 750K

and 850K are presented. The structure investigation were carried out using conventional light-, scanning- (SEM) and transmission electron

microscopy (TEM). The results presented here are supplementary to the mechanical studies given in part I of this investigations. The

results of study concerning mechanical properties degradation and structure observations show that the differences in mechanical

properties of alloy subjected different temperature are caused by more advanced processes of structure degradation during long-term aging

at 850K, compare to that at 750K. Higher service temperature leads to formation of large precipitates of δ phase. The nucleation and

growth of needle- and/or plate-like, relative large delta precipitates proceed probably at expense strengthening γ" phases. Moreover, it can't

be excluded that the least stable γ" phase is replaced with more stable γ' precipitates. TEM observations have disclosed differences in

dislocation structure of alloy aged at 750K and 850K. The dislocation observed in alloy subjected to 750K are were seldom observed only,

while in that serviced at high stress and 850K dislocation array and dislocation cell structure was typical.

The paper proposes a methodology useful in verification of results of dilatometric tests aimed at determination of temperatures defining

the start and the end of eutectoid transformation in the course of ductile cast iron cooling, based on quenching techniques and

metallographic examination. For an industrial melt of ductile cast iron, the effect of the rate of cooling after austenitization at temperature

900°C carried out for 30 minutes on temperatures TAr1

start and TAr1

end was determined. The heating rates applied in the study were the

same as the cooling rates and equaled 30, 60, 90, 150, and 300°C/h. It has been found that with increasing cooling rate, values of

temperatures TAr1

start and TAr1

end decrease by several dozen degrees.

Statistical Process Control (SPC) based on the well known Shewhart control charts, is widely used in contemporary manufacturing

industry, including many foundries. However, the classic SPC methods require that the measured quantities, e.g. process or product

parameters, are not auto-correlated, i.e. their current values do not depend on the preceding ones. For the processes which do not obey this

assumption the Special Cause Control (SCC) charts were proposed, utilizing the residual data obtained from the time-series analysis. In the

present paper the results of application of SCC charts to a green sand processing system are presented. The tests, made on real industrial

data collected in a big iron foundry, were aimed at the comparison of occurrences of out-of-control signals detected in the original data

with those appeared in the residual data. It was found that application of the SCC charts reduces numbers of the signals in almost all cases

It is concluded that it can be helpful in avoiding false signals, i.e. resulting from predictable factors.

The chosen, typical causes of quality defects of cast-iron „alphin” rings embedded in aluminum cast are being presented in this paper.

Diffusive joint of those inserts with the pistons casts is being used, due to extreme work conditions of destructive influence of the fuel mix

and variable thermo-mechanical loads, which reign in the combustion motor working chamber.

The gas-tungsten arc (GTA) welding behaviors of a magnesium matrix composite reinforced with SiC particles were examined in terms of

microstructure characteristics and process efficiencies. This study focused on the effects of the GTAW process parameters (like welding

current in the range of 100/200 A) on the size of the fusion zone (FZ). The analyses revealed the strong influence of the GTA welding

process on the width and depth of the fusion zone and also on the refinement of the microstructure in the fusion zone. Additionally, the

results of dendrite arm size (DAS) measurements were presented.

Topic of this work is to compare metalurgy of cast irons poured into sand moulds and into shell molds at IEG Jihlava company and from it

following differencies in structures of thin- and thick-walled castings. This work is dealing with investigation and experimental

measurement on surfaces and sections suitable thin- and thick-walled investment castings at IEG Jihlava. Cast irons with flake graphite

(grey cast iron) and cast irons with spheroidal graphite (ductile cast iron). Both mechanical and physical properties are determined using

calculations from as measured values of wall thicknesses L and Lu, Vickers hardness and remanent magnetism. Measurement results are

discussed, findings are formulated and methods for castings metallurgical quality improvement are recommended finally

The article shows results of studies of primary crystallization and wear resistance of Cr-Ni-Mo cast steel intended for work in corrosive

and abrasive conditions. The studies of primary crystallization were conducted with use of TDA method and modified tester allowing

measurement casting cooling time influence on the cooling and crystallization curves of studied alloys. After heat treatment of examined

cast steel wear tests of the samples were conducted on pin-on-disc type device.

The paper presents the results of hypoeutectic silumin 226 grade and silumin produced on its basis through the addition of V and Mo.

Vanadium and molybdenum were added as the preliminary alloy AlV10 and AlMo8 in an amount providing the concentration of 0.1; 0.2;

0.3 and 0.4% V and Mo. TDA curves of tested silumins were presented; regardless of the chemical composition there were similar thermal

effects. Pressure castings microstructure research revealed the presence in silumins with the addition of V and Mo phases do not occur in

silumin without these additives. These phases have a morphology similar to the walled, and their size increases with increasing

concentration of V and Mo. The size of the precipitates of these phases silumin containing 0.1% V and Mo does not exceed 10 microns,

while 0.4% of the content of these elements increases to about 80 microns. Tests of basic mechanical properties of silumins were carried

out. It has been shown that the highest values of tensile strength Rm = 295 MPa and elongation A = 4.2% have silumin containing

approximately 0.1% V and Mo. Increasing concentrations of these elements causes a gradual lowering of the Rm and A values.

A vertical cut at the mid-depth of the 15-ton forging steel ingot has been performed by curtesy of the CELSA – Huta Ostrowiec plant.

Some metallographic studies were able to reveal not only the chilled undersized grains under the ingot surface but columnar grains and

large equiaxed grains as well. Additionally, the structural zone within which the competition between columnar and equiaxed structure

formation was confirmed by metallography study, was also revealed. Therefore, it seemed justified to reproduce some of the observed

structural zones by means of numerical calculation of the temperature field. The formation of the chilled grains zone is the result of

unconstrained rapid solidification and was not subject of simulation. Contrary to the equiaxed structure formation, the columnar structure

or columnar branched structure formation occurs under steep thermal gradient. Thus, the performed simulation is able to separate both

discussed structural zones and indicate their localization along the ingot radius as well as their appearance in term of solidification time.

This study summarises the research efforts undertaken in iron foundry plants in which the process are mostly automated and mechanised.

The research program was limited in scope, focusing on causes of surface defects in castings products that are attributable to the

bentonite-containing sand and the mould system. One of the potential roots of surface defects is heterogeneity of sand grains, containing

lumped ball-shaped grains and irregular pellets with a layered-structure. The moisture contents of those lumped grains is different than

the moisture level required in the process, besides these grains may contain various elements and metallic compounds which, when cast

into moulds, may react with molten metals in an uncontrolled manner. As a result, surface defects are produced, such as surface blowholes,

burst penetration, sand holes, slag inclusions, pinhole porosity. This study investigated the efficiency of key sand preparation and

moulding machines and installations integrated into the casting process line. The efficiency of machines and installations is defined in

terms of quality parameters of sand mix and moulds, which are associated with the emergence of surface defects on castings.

The obtained results of heating of sand moulds with binders by means of a thermal radiation of liquid metal are presented in this study.

Standard samples for measuring Rg made of the tested moulding sands were suspended at the lower part of the cover which was covering

the crucible with liquid metal (cast iron), placed in the induction furnace. The authors own methodology was applied in investigations. The

progressing of the samples surface layers heating process was determined as the heating time function. Samples of a few kinds of

moulding sands with chemical binders were tested. Samples without protective coatings as well as samples with such coatings were tested.

The influence of the thermal radiation on bending resistance of samples after their cooling was estimated. The influence of several

parameters such as: time of heating, distance from the metal surface, metal temperature, application of coatings, were tested. A very fast

loss of strength of moulding sands with organic binders was found, especially in cases when the distance between metal and sample

surfaces was small and equaled to 10÷15 mm. Then, already after app. 15 seconds of the radiation (at Tmet=1400o

C), the resistance

decreases by nearly 70%. Generally, moulding sands with organic binders are losing their strength very fast, while moulding sands with

water glass at first increase their strength and later slightly lose. The deposition of protective coatings increases the strength of the mould

surface layers, however does not allow to retain this strength after the metal thermal radiation.

Solidification of AlSiFe alloys was studied using a directional solidification facility and the CALPHAD technique was applied to calculate

phase diagrams and to predict occurring phases. The specimens solidified by electromagnetic stirring showed segregation across, and the

measured chemical compositions were transferred into phase diagrams. The ternary phase diagrams presented different solidification paths

caused by segregation in each selected specimen. The property diagrams showed modification in the sequence and precipitation

temperature of the phases. It is proposed in the study to use thermodynamic calculations with Thermo-Calc which enables us to visualize

the mushy zone in directional solidification. 2D maps based on property diagrams show a mushy zone with a liquid channel in the

AlSi7Fe1.0 specimen center, where significant mass fraction (33%) of β-Al5FeSi phases may precipitate before α-Al dendrites form.

Otherwise liquid channel occurred almost empty of β in AlSi7Fe0.5 specimen and completely without β in AlSi9Fe0.2. The property

diagrams revealed also possible formation of α–Al8Fe2Si phases.

Achieving control of coating thickness in foundry moulds is needed in order to guarantee uniform properties of the mould but also to

achieve control of drying time. Since drying time of water based coatings is heavily dependent on the amount of water present in the

coating layer, a stable coating process is prerequisite for a stable drying process. In this study, we analyse the effect of different variables

on the coating layer properties. We start by considering four critical variables identified in a previous study such as sand compaction,

coating density, dipping time and gravity and then we add centre points to the original experimental plans to identify possible non-linear

effects and variation in process stability. Finally, we investigate the relation between coating penetration (a variable that is relatively

simple to measure in production) and other coating layer thickness properties (relevant for the drying process design). Correlations are

found and equations are provided. In particular it is found that water thickness can be directly correlated to penetration with a simple linear

equation and without the need to account for other variables.

Turbine blades have complex geometries with free form surface. Blades have different thickness at the trailing and leading edges as well

as sharp bends at the chord-tip shroud junction and sharp fins at the tip shroud. In investment casting of blades, shrinkage at the tip-shroud

and cord junction is a common casting problem. Because of high temperature applications, grain structure is also critical in these castings

in order to avoid creep. The aim of this work is to evaluate the effect of different process parameters, such as, shell thickness, insulation

and casting temperature on shrinkage porosity and grain size. The test geometry used in this study was a thin-walled air-foil structure

which is representative of a typical hot-gas-path rotating turbine component. It was observed that, in thin sections, increased shell

thickness helps to increase the feeding distance and thus avoid interdendritic shrinkage. It was also observed that grain size is not

significantly affected by shell thickness in thin sections. Slower cooling rate due to the added insulation and steeper thermal gradient at

metal mold interface induced by the thicker shell not only helps to avoid shrinkage porosity but also increases fill-ability in thinner

sections.

At thermal junctions of aluminium alloy castings and at points where risering proves to be difficult there appear internal or external

shrinkages, which are both functionally and aesthetically inadmissible. Applying the Probat Fluss Mikro 100 agent, which is based on

nano-oxides of aluminium, results in the appearance of a large amount of fine microscopic pores, which compensate for the shrinking of

metal. Experimental tests with gravity die casting of AlSi8Cu3 and AlSi10Mg alloys have confirmed that the effect of the agent can be of

advantage in foundry practice, leading to the production of castings without local concentrations of defects and without the appearance of

shrinkages and macroscopic gas pores. Also, beneficial effect on the mechanical properties of the metal has been observed.

Cast Hadfield steel is characterised by high abrasion resistance, provided, however, that it is exposed to the effect of dynamic loads.

During abrasion without loading, e.g. under the impact of loose sand jet, its wear resistance drops very drastically. To increase the abrasion

resistance of this alloy under the conditions where no pressure is acting, primary vanadium carbides are formed in the metallurgical

process, to obtain a composite structure after the melt solidification. The primary, very hard, carbides uniformly distributed in the

austenitic matrix are reported to double the wear resistance of samples subjected to the effect of a silicon carbide-water mixture.

The formation of oxide film on the surface of aluminium melts, i.e. bifilms, are known to be detrimental when they are incorporated into

the cast part. These defects causes premature fractures under stress, or aid porosity formation. In this work, Al-12 Si alloy was used to cast

a step mould under two conditions: as-received and degassed. In addition, 10 ppi filters were used in the mould in order to prevent bifilm

intrusion into the cast part. Reduced pressure test samples were collected for bifilm index measurements. Samples were machined into

standard bars for tensile testing. It was found that there was a good agreement with the bifilm index and mechanical properties.