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Number of results: 11
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Abstract

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.

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Authors and Affiliations

J. Pezda
A. Jarco
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Abstract

The paper presents the results of research of impact strength of aluminum alloy EN AC-44200 based composite materials reinforced with

alumina particles. The research was carried out applying the materials produced by the pressure infiltration method of ceramic preforms

made of Al2O3 particles of 3-6m with the liquid EN AC-44200 Al alloy. The research was aimed at determining the composite resistance

to dynamic loads, taking into account the volume of reinforcing particles (from 10 to 40% by volume) at an ambient of 23°C and at

elevated temperatures to a maximum of 300°C. The results of this study were referred to the unreinforced matrix EN AC-44200 and to its

hardness and tensile strength. Based on microscopic studies, an analysis and description of crack mechanics of the tested materials were

performed. Structural analysis of a fracture surface, material structures under the crack surfaces of the matrix and cracking of the

reinforcing particles were performed.

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Authors and Affiliations

A. Kurzawa
J.W. Kaczmar
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Abstract

The series of experiments was performed on commercial polymeric composite material MultimetalStahl 1018. Strength tests were performed to determine the yield point of the material. The composite had the highest hardness at a temperature of 20°C. Hardness and microhardness were determined in further experiments. The adhesiveness of the material to metal surfaces and impact strength were also analyzed. The scanning electron microscopy and X-ray microanalysis methods were used for analyzing the microstructure of the material. Chemical composition of selected areas was analyzed, which allowed for a preliminary identification of metallic elements content in the composite. The microstructure of composite is highly non-homogeneous and particular phases are highly elongated and angular. The analyzed phase was enriched with silicon, aluminium, magnesium, iron and vanadium other phases enriched with metallic elements, e.g. molybdenum, titanium, vanadium and also oxygen as well as traces of cadmium and chromium. The results were presented in the form of photos and illustrations. The results confirmed the applicability of the composite as a binder for fixing mechanical and foundry devices.

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Authors and Affiliations

D. Kalisz
A. Arustmian
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Abstract

The morphology of G20Mn5 specimens made of non-modified and rare earth metals (REM) modified cast steel was investigated. Molten metal was treated with a cerium-rich mischmetal contain 49.8% Ce, 21.8% La, 17.1% Nd, 5.5% Pr and 5.35% other rare earth metals making up the balance. The melting, quenching (920°C/water) and tempering (720°C/air) were performed under industrial conditions. Analysis included G20Mn5 cast steel fracture specimens subjected to Charpy V-notch impact testing at 20°C, -30°C and -40°C. The purpose of the analysis was to determine the influence of REM on the microstructure and mechanical properties of G20Mn5 cast steel and the REM effect on the morphology, impact strength and character of the fracture surfaces. In addition, a description of the mechanism by which fracture occurred in the two materials was proposed. The author demonstrated the beneficial effects of adding REM to molten steel, manifested by a 20 - 40% increase in impact toughness, depending on test temperature, as compared to the non-modified cast steel. Important findings included more than 100% increase in impact strength in comparison with the required impact toughness of 27J at -40C for heat treated steels (EN 10213).

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Authors and Affiliations

Justyna Kasińska
ORCID: ORCID
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Abstract

The paper presents the results of research on microstructure and impact strength of AlSi13Cu2 matrix composite reinforced by Ni-coating carbon fibers (CF) with a volume fraction of 5%, 10% and 15%. The composite suspensions were prepared using by stirring method and subsequently squeeze casted under different pressures of 25, 50, 75 and 100 MPa. As part of the study, fiber distribution in aluminum matrix was evaluated and variation in impact strength of composite as a function of the carbon fibers volume fraction and pressure applied were determined. It has been found that the presence of Ni coating on carbon fibers clearly improves their wettability by liquid aluminum alloy and in combination with the stirring parameters applied, composite material with relatively homogeneous structure can be produced. Charpy's test showed that the impact strength of composite reaches the highest value by carrying out the squeeze casting process at 75 MPa. In the next stage of research, it was found that the impact strength of composites increases with the increase of carbon fibers volume fraction and for 15% of fibers is close to 8 J/cm2. Observations of fracture surfaces have revealed that crack growth in the composites propagates with a quasi-cleavage mechanism. During the creation of the fracture, all fibers arranged perpendicular to its surface were sheared. At the same time, the metal matrix around the fibers deformed plastically creating characteristic ductile breaks. The fracture surface formation through the fibers indicates a cohesive and strong connection of the reinforcement with the matrix. In addition to the phenomena mentioned, debonding the fiber-matrix interfaces and the formation of voids between components were observed on the fracture surface.

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Authors and Affiliations

A. Zyska
Z. Konopka
Małgorzata Łągiewka
ORCID: ORCID
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Abstract

Two standardised grades of spheroidal cast iron determined in standard EN PN 1563 – 1997 as: EN-GJS-350 – 22LT (T = –40°C) and EN GJS 400 – 18LT (T = –20°C) are intended for work at low temperatures: –20 and –40oC. The main mechanical property of these cast iron grades is a high impact strength at a work temperature down to: –40°C. A series of controlled melts was performed to optimise the production technology of spheroidal cast iron, which in as-cast state is characterised by ferritic matrix (the best without any pearlite), fine precipitates of nodular graphite and high purity (without non-metallic inclusions). Variable structures of metal charges and various spheroidisation techniques (the modification methods) (slender ladle with a tight cover – Tundish technology as well as the technology with cored wire) were applied in the research. In order to obtain refinement of graphite precipitates and to achieve the ferritic matrix multistage inoculations of technologies were applied. Cast iron was subjected to refining to limit non-metallic inclusions since they decrease the impact strength. The production process of cast iron was controlled by the thermal derivative analysis at the stage of initial cast iron and after its secondary metallurgy (modification and inoculation). It was pointed out, that the reproducible production of cast iron for work at low temperatures was only possible when all elements of the technological process were strictly adhered to. It was pointed out, in the hereby paper, that: it should be strived to maintain Si content not higher than 2.50÷2.60%, which at producing spheroidal cast iron is sometimes difficult and requires using a lot of pig iron in the metal charge. For a fast assessment of the cast iron quality, concerning its impact strength, the proposed – in the hereby paper – index quality (IQu) can be applied. It is determined on the bases of measuring the cast iron hardness and propagation velocity of ultrasound wave.
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Authors and Affiliations

J. Zych
1
ORCID: ORCID
T. Jurga
2
J. Mocek
1
M. Myszka
1
T. Snopkiewicz
1

  1. AGH University of Science and Technology, Faculty of Foundry Engineering, Al. Mickiewicza 30, 30-059 Kraków, Poland
  2. Odlewnia Żeliwa Drawski S.A, Drawski Młyn, Poland
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Abstract

Cast high-manganese Hadfield steel is commonly used for machine components operating under dynamic load conditions. Their high fracture toughness and abrasive wear resistance is the result of an austenitic structure, which - while being ductile - at the same time tends to surface harden under the effect of cold work. Absence of dynamic loads (e.g. in the case of sand abrasion) causes rapid and premature wear of parts. In order to improve the abrasive wear resistance of cast high-manganese steel for operation under the conditions free from dynamic loads, primary titanium carbides are produced in this cast steel during melting process to obtain in castings, after melt solidification, the microstructure consisting of an austenitic matrix and primary carbides uniformly distributed therein. After heat treatment, the microhardness of the austenitic matrix of such cast steel is up to 580 μHV20 and the resulting carbides may reach even 4000 μHV20. The impact strength of this cast steel varies from 57 to 129 and it decreases with titanium content. Compared to common cast Hadfield steel, the abrasive wear resistance determined in Miller test is at least twice as high for the 0.4% Ti alloy and continues growing with titanium content.

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Authors and Affiliations

R. Zapała
G. Tęcza
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Abstract

The paper presents the microstructure and selected properties of ausferritic nodular cast iron annealed at the temperature 520 and 550°C.

This choice was dictated by the temperatures used in the practice of nitriding. Nodular graphite in cast iron was obtained with use of

Inmold process. Cast iron containing molybdenum and copper ensuring obtaining an ausferrite in the cast iron matrix without the use of

heat treatment of castings was tested. The effect of annealing temperature on the microstructure and the kind of fracture of the ausferritic

nodular cast iron was presented. The effect of an annealing temperature on hardness, impact strength and the microhardness of ausferritic

nodular cast iron matrix was shown too. The lamellar structure of phases in the cast iron matrix after annealing has been ascertained. There

has been an increase in hardness of an annealed cast iron and microhardness of its matrix. The reduction in the impact strength of the cast

iron annealed at 520 and 550°C was approximately 10-30%. Both an increase in the hardness of cast iron as well as an decrease in its

impact strength is probably due to the separation of secondary carbides during the heat treatment.

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Authors and Affiliations

G. Gumienny
L. Klimek
B. Kurowska
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Abstract

The subject of this study is to show that the parameters of the melting process of high chromium cast iron affect the cost of casting and the properties of the cast iron. The analysis of the quality of the casting and its price was conducted in terms of the metal charge of high chromium cast iron. As is well known, in order to obtain the correct structure of the casting, and thus good strength properties, it is necessary to use clean batch components free of undesirable impurities. Unfortunately, the quality of the metal charge is proportional to its price. Thus, the use of expensive batch components offers the possibility of obtaining healthy and meeting the strength properties of castings. However, there is a flaw in this approach. And it is from the point of view of economics that production plants are forced to look for savings. Expensive feedstock materials are replaced by cheaper counterparts giving the possibility of obtaining castings with similar properties often, however, at the cost of increased inferior quality. It seems that a way out of this situation is to introduce a modification procedure into the alloyed iron manufacturing technology. The selected modifiers should affect the fragmentation of the structure of the primary austenite. At this point, it can be hypothesized that this will result in the elimination of hot cracking in high chromium cast iron. The industrial research carried out at the "Swidnica" Foundry Ltd. made it possible to show by means of the Althoff-Radtke method that by using the modification of the liquid metal of the so-called "inferior and cheaper" composition of the metal charge, a reduction in the occurrence of hot cracks and shrinkage cavities can be achieved. In addition, iron-niobium modification not only reduced the formation of casting defects in castings, but also slightly improved the impact strength of high-chromium cast iron. The work was written as part of an implementation PhD.
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Bibliography

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Authors and Affiliations

Jan Mędoń
1
ORCID: ORCID
Andrzej Szczęsny
1
ORCID: ORCID
Eugeniusz Ziółkowski
1
ORCID: ORCID
Edward Guzik
1
ORCID: ORCID
M. Czarny
2
Dariusz Kopyciński
1
ORCID: ORCID

  1. AGH University of Krakow, al. Adama Mickiewicza 30, 30-059 Kraków, Poland
  2. Odlewnia „Świdnica” Sp. z o.o., Świdnica ul. Kliczkowska 53, Poland
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Abstract

The results of the Charpy impact test of AE-type magnesium alloys produced by the high pressure die casting method are presented. Three alloys with different weight fractions of rare earth elements (RE; e.g. 1, 3 and 5 wt%) and the same mass fraction of aluminium (5 wt%) were prepared. The casts were fabricated using a typical cold chamber high pressure die casting machine with a 3.8 MN locking force. Microstructural analyses were performed by means of a scanning electron microscope (SEM). The impact strength (IS) was determined using a Charpy V hammer with an impact energy equal to 150 J. The microstructure of the experimental alloys consisted of an -Mg solid solution and Al11RE3, Al10Ce2Mn7 and Al2RE intermetallic compounds. The obtained results show the significant influence of the rare earth elements to aluminium ratio on the impact strength of the investigated materials. Lower the RE/Al ratio in the chemical composition of the alloy results in a higher impact strength of the material.

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Authors and Affiliations

Katarzyna Braszczyńska-Malik
ORCID: ORCID
M.A. Malik

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