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1

Effect of Alloying Additives and Casting Parameters on the Microstructure and Mechanical Properties of Silicon Bronzes

Witasiak Dawid, Garbacz-Klempka Aldona, Papaj M., Papaj P., Piękoś Marcin, Kozana Janusz, Maj Maria, Peret-Nowak Małgorzata

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 3

110--117

EN

The studied silicon bronze (CuSi3Zn3Mn1) is characterised by good strength and corrosion resistance due to the alloying elements that are present in it (Si, Zn, Mn, Fe). This study analysed the casting process in green sand moulding, gravity die casting, and centrifugal casting with a horizontal axis of rotation. The influences of Ni and Zr alloying additives as well as the casting technology that was used were evaluated on the alloy’s microstructure and mechanical properties. The results of the conducted research are presented in the form of the influence of the technology (GS, GZ, GM) and the content of the introduced alloy additives on the mechanical parameters (UTS, A10, and Proof Stress, BHN). The analysis of the tests that were carried out made it possible to determine which of the studied casting technologies had the best mechanical properties. Microstructure of metal poured into metal mould was finer than that which was cast into moulding compound. Mechanical properties of castings made in moulding compound were lower than those that were cast into metal moulds. Increased nickel content affected the BHN parameter.

2

Assessment of Foundry Chromite Sand Crushability under Thermal-Mechanical Loading

Kabasele Jonathan K., Nyembwe Kasongo D., Polzin H.

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 3

16--21

EN

When used for sand casting, foundry sand is stressed in several ways. These stresses, thermal and mechanical, compromise the grain integrity, resulting in size reduction and the production of small particles to the point where the sand is no longer viable for sand casting. This study evaluates the crushability of chromite sand, a crucial characteristic for determining how resistant sand is to size reduction by crushing. To replicate the heat and mechanical strain that sand is subjected to during the industrial sand-casting process, a sinter furnace and rod mill were employed. After nine minutes of heat and mechanical stress application, the crushing ratio, which was used to gauge the crushability of chromite sand, ranged from 1.72 to 1.92 for all samples. There were differences in the rate at which fine particles were produced among the samples, with sample E producing the highest proportion of fine particles in the same length of time. Understanding the properties that control the crushability performance of chromite sand will enable foundries to buy chromite sand with higher recycling yield, reducing the environmental impact of waste foundry sand and eliminating the risk to the workforce's pulmonary health in line with the current industry standards. Foundries will also be able to optimize the current industrial process while continually pushing for innovative foundry technologies and materials.

3

Mechanical and Thermal Properties of Aluminum Foams Manufactured by Investment Casting Method

Dmitruk Anna, Kapłon H., Naplocha K.

Archives of Foundry Engineering

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2022

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Vol. 22, iss. 1

37--42

EN

A method for the open-cell aluminum foams manufacturing by investment casting was presented. Among mechanical properties, compressive behaviour was investigated. The thermal performance of the fabricated foams used as heat transfer enhancers in the heat accumulator based on phase change material (paraffin) was studied during charging-discharging working cycles in terms of temperature distribution. The influence of the foam on the thermal conductivity of the system was examined, revealing a two-fold increase in comparison to the pure PCM. The proposed castings were subjected to cyclic stresses during PCM’s subsequent contraction and expansion, while any casting defects present in the structure may deteriorate their durability. The manufactured heat transfers enhancers were found suitable for up to several dozen of cycles. The applied solution helped to facilitate the heat transfer resulting in more homogeneous temperature distribution and reduction of the charging period’s duration.

4

Evaluation of Wear Mechanisms of Graphites Used for Crystallisers for Continuous Casting

Brudny Anna, Kulasa Joanna, Juszczyk Barbara, Myalski Jerzy, Roskosz Stanisław, Wycisk R., Kwaśniewski Paweł, Strzępek Paweł, Poręba Marek

Archives of Foundry Engineering

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2022

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Vol. 22, iss. 4

109--115

EN

This paper presents the results of research concerning the evaluation of tribological properties of graphite materials used, among others, for crystallisers for continuous casting of non-ferrous metals and their alloys. Graphite materials differing not only in their physical properties but also in the technology of their production were selected from a wide range of commercially available products. Wear resistance investigations of the tested graphite materials were carried out on a pin-on-disc tribometer under technically dry friction conditions on a sliding distance of 1000 m. A constant load but variable speed was used in the tests. The mean value of the coefficient of friction and the wear of the material were determined based on the tribological tests carried out. It was observed that as the speed increases, the average value of the coefficient of friction decreases, while the wear increases. A microstructural analysis of the wear track showed that the friction mechanism depends mainly on the graphite formation technology, which is related to the microstructure of the tested materials, and to a lesser extent to their physical and mechanical properties. Varying the speed values made it possible to trace changes in the wear mechanism, on the basis of which it is possible to predict the durability and reliability of graphite crystalliser operation.

5

Using of Technology Semisolid Squeeze Casting by Different Initial States of Material

Martinec D., Pastirčák R., Kantoríková E.

Archives of Foundry Engineering

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2020

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Vol. 20, iss. 1

117--121

EN

The paper deals with the effect of heating of various prepared batch materials into semisolid state with subsequent solidification of the cast under pressure. The investigated material was a subeutectic aluminium alloy AlSi7Mg0.3. The heating temperature to the semisolid was chosen at 50% liquid phase. The used material was prepared in a variety of ways: heat treatment, inoculation and by squeeze casting. Also the influence of the initial state of material on inheritance of mechanical properties and microstructure was observed. The pressure was 100 MPa. Effect on the resulting casting structure, alpha phase distribution and eutectic silicon was observed. By using semisolid squeeze casting process the mechanical properties and microstructures of the casts has changed. The final microstructure of the casts is very similar to the microstructure that can be reached by technology of thixocasting. The mechanical properties by using semisolid squeeze casting has been increased except the heat treated material.

6

The Effect of Bifilm and Sr Modification on the Mechanical Properties of AlSi12Fe Alloy

Uludağ M., Gurtaran M., Dispinar D.

Archives of Foundry Engineering

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2020

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Vol. 20, iss. 3

99--104

EN

The microstructure of Al-Si alloy has coarse silicon and this structure is known dangerous for mechanical properties due to its crack effect. Sr addition is preferred to modify the coarse silica during solidification. Additionally, bifilms (oxide structure) are known as a more dangerous defect which is frequently seen in light alloys. It is aimed at that negative effect of bifilms on the properties of the alloys tried to be removed by the degassing process and to regulate the microstructure of the alloy. In this study, the effect of degassing and Sr modification on the mechanical properties of AlSi12Fe alloy was investigated, extensively. Four different parameters (as-received, as-received + degassing, Sr addition, Sr addition + degassing) were studied under the same conditions environmentally. The microstructural analyses and mechanical tests were done on cast parts. All data obtained from the experimental study were analyzed statistically by using statistical analysis software. It was concluded from the results that Sr addition is very dangerous for AlSi12Fe alloy. It can be suggested that to reach high mechanical properties and low casting defects, the degassing process must be applied to all castings whereas Sr addition should not be preferred.

7

Attempts to Prepare Precision Composite Castings by Sintering Al2O3/AlSi11 Using Underpressure

Szymański P., Gawdzińska K., Nagolska D.

Archives of Foundry Engineering

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2020

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Vol. 20, iss. 1

49--54

EN

This article presents the preparation of composite casts made using the technology of precise casting by the method of melted models. The composite was reinforced with the ceramic sinter from Al2O3 particle shaped in a printed polystyrene female mould, which was fired together with precured ceramics. The resulting ceramic preform, after being saturated with paraffin and after the filling system is installed, was filled with liquid moulding sand and fired together with the mould. The reinforcement was saturated by means of the counter-pressure exerting action on the metal column, being a resultant of pressures inside and outside the chamber. The preliminary assessment showed no apparent defects in the shape of the cast. The casting was measured and the figures were compared with the dimensions of the matrix in which the reinforcing preform was made, the preform after firing and after saturation with paraffin. The results were presented in a table and dimensional deviations were determined. The composite casting was subjected to metallographic tests, which excluded any porous defects or damage to the reinforcement. It can therefore be said that, according to the predictions resulting from the previous calculations, the pressure values used allowed for complete filling of the reinforcement capillaries. The proposed method is therefore suitable for the preparation of precision composite castings with complex shapes.

8

Application of Modular Die for Fluidity Test and Monitoring of the Pressing Force Flow by Semi-solid Squeeze Casting of AlSi7Mg0.3

Martinec D., Pastirčák R.

Archives of Foundry Engineering

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2020

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Vol. 20, iss. 3

69--73

EN

The fluidity is the term to determine the materials ability to fill the mold cavity properly. Fluidity is complex property with many variables. Up to this date, there is no methodology for defining the fluidity in a semisolid material state. Submitted paper deals with the proposal of a new method designed for aluminium alloy fluidity evaluation in semi-solid state trough the design of the layered construction die. Die will be primary used for fluidity tests of semi-solid squeeze casted aluminium alloy and to observe the pressing force flow by mentioned casting technology. The modularity consists of possibility to change each die segment. In the experiment the die design was evaluated by simulation in ProCAST 11.5 and by production of experimental castings. The die was made by laser cutting technology from construction steel S355JR. Experimental material was aluminium alloy AlSi7Mg0.3. The temperature of the semisolid state was chosen to achieve 35% of solid phase. The result of next study should be a selected parameters observation and their effect on the fluidity of aluminium alloy in semi-solid state. This will be very important step to determine the optimal conditions to achieve a castings with certain wall thickness produced by the method of semi-solid squeeze casting.

9

Lead-Free Casting Brasses. Investigations of the Corrosion Resistance and Shaping of Microstructure and Properties

Kozana J., Garbacz-Klempka A., Piękoś M.

Archives of Foundry Engineering

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2019

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iss. 2

113--118

EN

The ecological factor is very important in shaping properties of alloys. It leads to a limitation or elimination, from the surroundings, of harmful elements from the heavy metals group. The so-called eco-brasses group comprises common lead-free brasses containing 10 to 40% of zinc and arsenic brasses of a high dezincification resistance. Among standardized alloys, CW511L alloy ( acc. to EN standard) or MS-60 alloy (acc. to DIN) can be mentioned. Investigations were performed on two different kinds of metal charges: ingots cast by gravity and the ones obtained in the semi-continuous casting technology with using crystallizers. The casting quality was analysed on the basis of the microstructure images and mechanical properties. The investigations also concerned increasing the corrosion resistance of lead-free alloys. This resistance was determined by the dezincification tendency of alloys after the introduction of alloying additions, i.e. aluminium, arsenic and tin. The investigations focused on the fact that not only alloying additions but also the production methods of charge materials are essential for the quality of produced castings. The introduced additions of aluminium and tin in amounts: 0÷1.2 wt% decreased the dezincification tendency, while arsenic, already in the amount of 0.033 wt%, significantly stopped corrosion, limiting the dezincification process of lead-free CuZn37 brass. At higher arsenic contents, corrosion occurs only within the thin surface layer of the casting (20 μ).

10

Cast Grates Used in Heat Treatment Furnaces

Piekarski B., Drotlew A.

Archives of Foundry Engineering

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2019

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iss. 3

49--54

EN

Examples of cast grates whose construction was based on previously used "old" patterns of the technological equipment for heat treatment furnaces (TEq) are presented. Manufacturers of this type of castings have at their disposal numerous earlier designs of the applied TEq. Their adaptation for the needs of a new order, i.e. the creation of a new design or modification of the already existing one, significantly reduces both cost and time of the implementation. It also allows making new grate constructions of various shapes and sizes, reducing in this way the number of patterns stored by the manufacturer of castings. The examples of cast grates shown and discussed in this study document the variety of ways that can be used when making them from the already existing patterns or castings. The presented grates were made using master patterns, entire castings or their fragments, and modular segments.

11

Thermally Hardened Moulding and Core Sands with Hydrated Sodium Silicate Designed for Al Alloy Castings

Major-Gabryś K. A., Grabarczyk A. P., Dobosz S. M.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 3

132--137

EN

The necessity of obtaining high quality castings forces both researchers and producers to undertake research in the field of moulding sands. The key is to obtain moulding and core sands which will ensure relevant technological parameters along with high environmental standards. The most important group in this research constitutes of moulding sands with hydrated sodium silicate. The aim of the article is to propose optimized parameters of hardening process of moulding sands with hydrated sodium silicate prepared in warm-box technology. This work focuses on mechanical and thermal deformation of moulding sands with hydrated sodium silicate and inorganic additives prepared in warm-box technology. Tested moulding sands were hardened in the temperature of 140ºC for different time periods. Bending strength, thermal deformation and thermal degradation was tested. Chosen parameters were tested immediately after hardening and after 1h of cooling. Conducted research proved that it is possible to eliminate inorganic additives from moulding sands compositions. Moulding sands without additives have good enough strength properties and their economic and ecological character is improved.

12

The Tendency of Moulding Sands to Generate Core Cracks

Grabarczyk A., Dobosz S. M., Kusiński J., Major-Gabryś K.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 1

157--161

EN

The constant growth of foundry modernization, mechanization and automation is followed with growing requirements for the quality and parameters of both moulding and core sands. Due to this changes it is necessary to widen the requirements for the parameters used for their quality evaluation by widening the testing of the moulding and core sands with the measurement of their resistance to mechanical deformation (further called elasticity). Following article covers measurements of this parameter in chosen moulding and core sands with different types of binders. It focuses on the differences in elasticity, bending strength and type of bond destruction (adhesive/cohesive) between different mixtures, and its connection to the applied bonding agent. Moulding and cores sands on which the most focus is placed on are primarily the self-hardening moulding sands with organic and inorganic binders, belonging to the group of universal applications (used as both moulding and core sands) and mixtures used in cold-box technology.

13

The Microstructure and Properties of the Bimetallic AZ91/AlSi17 Joint Produced by Compound Casting

Mola R., Bucki T.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 1

71--76

EN

Bimetallic AZ91/AlSi17 samples were produced by compound casting. The casting process involved pouring the AZ91 magnesium alloy heated to 650ºC onto a solid AlSi17 aluminum alloy insert placed in a steel mould. Prior to casting, the mould with the insert inside was heated to about 370ºC. The bonding zone formed between AZ91 and AlSi17 had a thickness of about 200 μm; it was characterized by a non-homogeneous microstructure. Two different areas were distinguished in this zone: the area adjacent to the AZ91 and the area close to the AlSi17. In the area closest to the AZ91 alloy, a eutectic composed of an Mg17Al12 intermetallic phase and a solid solution of Al in Mg was observed. In bonding zone at a certain distance from the AZ91 alloy an Mg2Si phase co-occurred with the eutectic. In the area adjacent to the AlSi17 alloy, the structure consisted of Al3Mg2, Mg17Al12 and Mg2Si. The fine Mg2Si phase particles were distributed over the entire Mg-Al intermetallic phase matrix. The microhardness of the bonding zone was much higher than those of the materials joined; the microhardness values were in the range 203-298 HV. The shear strength of the AZ91/AlSi17 joint varied from 32.5 to 36 MPa.

14

Microstructural and Tribological Characterization of Aluminium Bronzes with Additions of Si and Cr

Pisarek B. P., Kowalski B., Atapek H., Polat Ş., Tüfekçi T.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 1

93--98

EN

The article presents the investigation results of the crystallization (performed by means of the TDA method) and the microstructure of complex aluminium bronzes with the content of 6% Al, 4% Fe and 4% Ni, as well as Si additions in the scope of 1–2% and Cr additions in the scope of 0.1–0.3%, which have not been simultaneously applied before. For the examined bronze, the following tests were performed: hardness HB, impact strength (KU2). For bronze CuAl6Fe4Ni4Si2Cr0.3, characterizing in the highest hardness, wear tests were conducted with dry friction and the dry friction coefficient. The investigations carried out by means of the X-ray phase analysis demonstrated the following phases in the microstructure of this bronze: αCu, γ2 and complex intermetallic phases based on iron silicide type Fe3Si (M3Si M={Fe,Cr,…}). Compared to the normalized aluminium bronzes (μ=0.18–0.23), the examined bronze characterizes in relatively low wear and lower friction coefficient during dry friction (μ=0.147±0.016).

15

Influence of Modification in Centrifugal Casting on Microstructure and Mechanical Properties of Silicon Bronzes

Garbacz-Klempka A., Kozana J., Piękoś M., Papaj P., Papaj P., Perek-Nowak M.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 3

11--18

EN

Silicon bronzes are characterised by good mechanical properties and by high corrosion and mechanical wear resistance. The process of sleeve casting by means of the centrifugal casting with the horizontal axis of the mould rotation was analysed. The assessment of the influence of modification and centrifugal casting parameters on the microstructure and mechanical properties of alloys was carried out in the hereby work. Zirconium was applied as a modifier. Speed of rotation of the mould was the variable parameter of the centrifugal casting. The investigation results were summarised on the basis of the microstructure analysis and mechanical properties determination: UTS, proof stress, A10 and BHN. The experiment aimed at finding the information in which way the modification together with changing the pouring parameters influence the mechanical properties of the CuSi3Zn3FeMn alloy.

16

Grain Refinement of AlSi7Mg0,3 Alloy Cast by Rheocasting SEED

Bryksí Stunová B., Bryksí V., Vitkova J.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 3

161--166

EN

The paper concerns experimental work studying chemical composition, structures and selected mechanical properties of castings produced by rheocasting method SEED. After previous experiments, which showed inclusions in the primary phase α(Al) when observing structures, hypothesis of external nuclei was taken. The main goal of the work was to determine the influence of inoculation by various additions of titanium/boron based inoculant on the structure and properties of AlSi7Mg0,3 alloy. The master alloy AlTi5B1 was added in amounts of 0,05, 0,1, 0,15, 0,2 wt %. Metallographic observation by light and SEM microscopy was used for analysing the structures. Measurements of grain size were realised and evaluated. Brinell hardness measurements were performed. Chemical composition was measured by GDS analysis. Undertaken experiments did not prove the effect of inoculation of combined AlTi5B1 master alloy on castings made of AlSi7Mg0,3 alloy made by rheocasting SEED at given amounts and conditions.

17

Advantages of Melting Cast Iron in Gas Cupola Furnaces

Grachev V.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 3

76--80

EN

The author has developed and patented several types of gas cupola furnaces, which, due to replacing coke with gas, do not emit carbon monoxide, sulfur dioxide and coke dust. The author has defined the optimal modes of gas-and-air mixture combustion, i.e. the optimal coefficient of air discharge and gas mixture escape speed in melting cast iron. It has been experimentally proved that from the point of view of obtaining the maximum temperature, the optimal was the process with some lack of air, i.e. with α = 0.98. The results of metallurgical studies used in the article allowed to develop an optimal structure of the gas cupola furnace with a heterogeneous refractory filling, and to establish the optimal composition of the filling. For the first time the optimal composition of the filling is given: 40% of chamotte, 30% of high-alumina refractory, 30% of electrode scrap. It has been noted that when gas cupola furnaces were used, the main environmental advantage was the reduction of dust emission into the atmosphere, CO and SO2 content.

18

The Influence of Home Scrap on Porosity of MgAl9Zn1 Alloy Pressure Castings

Konopka Z., Chojnacki A., Łągiewka M., Zyska A.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 1

99--102

EN

The work presents the results of examinations concerning the influence of various amounts of home scrap additions on the porosity of castings made of MgAl9Zn1 alloy. The fraction of home scrap in the metal charge ranged from 0 to 100%. Castings were pressure cast by means of the hot-chamber pressure die casting machine under the industrial conditions in one of the domestic foundries. Additionally, for the purpose of comparison, the porosity of specimens cut out directly of the MgAl9Zn1 ingot alloy was also determined. The examinations consisted in the qualitative assessment of porosity by means of the optical microscopy and its quantitative determination by the method of weighting specimens in air and in water. It was found during the examination that the porosity of castings decreases with an increase in the home scrap fraction in the metal charge. The qualitative examinations confirmed the beneficial influence of the increased home scrap fraction on the porosity of castings. It was concluded that the reusing of home scrap in a foundry can be a good way of reduction of costs related to the production of pressure castings.

19

The Influence of Home Scrap on Mechanical Properties of MgAl9Zn1 Alloy Castings

Konopka Z., Chojnacki A. C., Łągiewka M., Zyska A.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 2

39--42

EN

The work presents the results of examinations concerning the influence of various amounts of home scrap additions on the properties of castings made of MgAl9Zn1 alloy. The fraction of home scrap in the metal charge ranged from 0 to 100%. Castings were pressure cast by means of the hot-chamber pressure die casting machine under the industrial conditions in one of the domestic foundries. The examinations consisted in the determination of the following properties: tensile strength Rm, yield strength Rp0.2, and the unit elongation A5, all being measured during the static tensile test. Also the hardness measurements were taken by the Brinell method. It was found that the mechanical properties (mainly the strength properties) are being improved up to the home scrap fraction of 50%. Their values were increased by about 30% over this range. Further rise in the home scrap content, however, brought a definite decrease in these properties. The unit elongation A5 exhibited continual decrease with an increase in the home scrap fraction in the metal charge. A large growth of hardness was noticed for the home scrap fraction increasing up to the value of 50%. Further increasing the home scrap percentage, however, did not result in a significant rise of the hardness value any more.

20

Method and Apparatus for Assessing the Properties of Slags

Biernat S., Bydałek A. W., Wołczyński W., Holtzer M.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 3

13--18

EN

A special Slag-Prop Cu database has been developed to archive data from laboratory and industrial tests related to post-reduction slags. In order to enrich the data areas, it was decided to design a system for measuring the temperature of the liquid slag and its viscosity. Objectives of research work are to gather information on the properties of post-slags such as the temperature of liquid slag and its viscosity. The discussed issues are especially important in the foundry practice. Designed research stand and using of database applications can greatly facilitate the work of metallurgists, foundrymen, technologists and scientists. The viscosity measurement was developed and presented earlier. The author's analytical methodology was supplemented by a thyristor measuring system (described in the article). The system temperature measurement can be performed simultaneously in 3 ways to reduce the measurement error. Measurement of the voltage mV - using the Seebeck effect can be measured throughout the entire range of thermocouple resistance, up to 1300 °C. Direct temperature measurement ⁰C - measurement only below 1000 ⁰C. Additional measurement - the measurement can also be read from the pyrometer set above the bath. The temperature and the reading frequency depend on the device itself. The principle of measurement is that in a molten metal / slag crucible, we put a N-type thermocouple. The thermocouples are hung by means of a tripod above the crucible and placed in a crucible. The thermocouple is connected to a compensating line dedicated to this type of thermocouple. The cable is in turn connected to a special multimeter that has the ability to connect to a computer and upload results. Temperature measurement can be performed simultaneously in 3 ways to reduce the measurement error. The Sn-Pb alloy has been subjected to testing for proper operation of the device. In this foot should be observed the supercooling of the liquid, which initiates the crystallization process and in which latent heat begins to exude raising the temperature until the coagulation temperature is reached.