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1

Influence of Melt Properties on the Dendritic Structure of Steel Castings

Aftandiliants Y., Gnyloskurenko Svyatoslav, Meniailo H., Khrychikov V.

Archives of Foundry Engineering

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2024

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Vol. 24, iss. 1

5--13

EN

The paper presents the experimental results on the determination of melt parameters such as the energy of the boundary, contact angle, density and kinematic viscosity of low and medium alloy steels at different temperatures, as well as the dispersion of their dendritic structure in solidified castings. The analysis of the data obtained allowed revealing using mathematical models the influence of the chemical composition and temperature of melts on their properties and the dendritic structure of castings. It was established the variation of the melt parameters depending on the particular chemical elements of steels as C, Si, Mn, O, P, V, Cr. The established analytical dependences shown that increasing density and viscosity contributes to the dispersion of the dendritic structure and viscosity is of the major effect. The derived quantitative patterns allows to evaluate structure formation of cast structural low and medium alloy steels.

2

Influence of process parameters in removing wastewater impurities via progressive freeze crystallization

Mazzam A.A., Hamizlan H.A., Jamal Ikhsan I.Z.A.I., Bakar M.N.F., Ab Hamid F.H.

Archives of Materials Science and Engineering

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2023

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Vol. 119, nr 2

56--61

EN

Purpose: The research aims to investigate the effect of the process parameter of progressive freeze concentration to eliminate tricholorophenol in wastewater. Design/methodology/approach: A stainless steel crystallizer was used throughout the experiment. Simulated wastewater containing trichlorophenol (TCP) was used as a sample solution, and ethylene glycol was utilized as a coolant to induce the heat transfer at a very low temperature. Progressive freeze crystallization (PFC) is an approach to purify water by implementing the fundamental concept of difference freezing point. In short, the PFC system produces ice-crystal layer by layer on a cooled surface until it forms a large and single-crystal block, leaving the impurities in the mother liquor. Findings: It is established that operating time and initial concentration influence the PFC performance. The findings show that the intermediate operating time gave the highest removal of TCP in wastewater. Meanwhile, for the effect of initial concentration, it was discovered that the lowest initial concentration resulted in the best TCP reduction with high purity of the water was obtained. Research limitations/implications: The results can be complemented by studies of the effect of coolant temperature and solution movement. These two parameters are believed to potentially improve the PFC performance. Practical implications: The findings can be implemented to select the optimal operating condition to treat the wastewater, especially in the industrial area with hazardous TCP. Originality/value: The obtained results testify to the predominant influence of operating time and initial concentration on the PFC performance in eliminating TCP in wastewater.

3

Explosive crystallisation of metal glasses based on Fe-B during pulsed laser heating. Experiment and modelling

Smolyakov O.V., Girzhon V.V., Mudry S.I., Nykyruy Y.S.

Archives of Materials Science and Engineering

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2023

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Vol. 119, nr 2

49--55

EN

Purpose: The structure evolution of amorphous metallic alloys during different kinds of thermal effects is an important problem of disordered systems physics. A precise evolutional model would allow predicting the formation of such a structural state, providing the necessary physical and mechanical alloy properties. Design/methodology/approach: The paper is devoted to the problem of modelling the explosive crystallisation process in metal glasses induced by laser, supplemented by experimental results. Findings: A theoretical model of laser-induced explosive crystallisation in metal glasses is proposed. A pulse laser heating method for the surface processing was developed, making it possible to obtain two-layer structures with an adjustable thickness of the amorphous crystalline layer. Research limitations/implications: The proposed model is assumed to test and optimes for metal glasses of other chemical compositions. Practical implications: A theoretical model of laser-induced explosive crystallisation in metal glasses allows for predicting and controlling structure changes to obtain the desired properties. Originality/value: The investigation of structure changes at rapid heating of amorphous alloys by experimental methods is very limited in obtaining data and their interpretation. For that reason, combining the modelling with experimental measurements is proposed. The results of this work have value for a scientist in material science, physics and engineering, which use nonequilibrium physical processes to obtain new materials, including nanoscale systems.

4

Regularities of Crystallization Heat Release During Solidification of Alloyed Cast Irons

Aftandiliants Y., Gnyloskurenko S., Meniailo H., Khrychikov V., Lomakin V.

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 1

110--117

EN

The chemical composition of alloys plays an important role at their crystallization and influences the solid phase formation, and thus, microstructure and properties. The present paper studies the release of the heat of crystallization of alloyed wear-resistant cast irons in order to determine the quantitative patterns of the chemical composition influence to the kinetics of crystallization. The differential thermal analysis was applied to get the data of heat release, its rate at cast iron temperature decrease. The normalized dependence of the amount of crystallization heat over time was obtained. The main temperature parameters were analyzed and four stages at irons crystallization were established and characterized with their duration and released heat. The multiple correlation analysis allowed considering a numerous physical and chemical factors and distinguishing their role at crystallization of irons. As a result, the quantitative regularities are determined of influencing the content of alloying elements, impurities and carbides on a heat and time of crystallization at the different stages of solidification, which are of great importance in developing alloyed irons with required quality and properties.

5

Effect of Iron Phases Crystallization on the Durability of the Bimetallic Connection Between Ring Inserts and the Piston Casting

Szucki Michał, Piątkowski Jarosław, Czerepak M.

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 2

112--118

EN

The article presents the most important causes of the unstable connection between cast iron ring inserts and the silumin casting of an engine piston. It is shown that manufacturing defects are mainly related to the alfin processing of inserts in Al-Si alloy (the so-called AS9 alloy). Exceeding the permissible iron content in AS9 alloy causes the crystallization of brittle -Al5FeSi phases. Their unfavorable morphology and large size are the main reasons for the weakening of the diffusion connection between the inserts and the piston, causing an unacceptable proportion of defective products. The study presented in this work was conducted under industrial conditions on a population of 10.000 pistons. Quality control data, production parameters, as well as the micro- and macro-structures of the cast iron inserts, and the interface area between the inserts and the silumin piston, were analyzed. Material and technological solutions have been proposed to reduce the occurrence of casting defects at the insert-piston joint. This includes the introduction of so-called "morphological correctors" of the -Al5FeSi phases, reducing the possibility of gaseous impurities in the AS9 alloy and optimizing the temperature of the alfin alloy.

6

Crystallization of GX2CrNiMoCuN 25-6-3-3 Grade Alloy Cast Steel and its Microstructure in the As-cast State and After Heat Treatment

Wróbel Tomasz, Jurczyk Paweł, Baron Czesław, Nuckowski Paweł M.

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 3

94--103

EN

The paper presents the results of research conducted in the field of crystallization and microstructure of duplex alloy cast steel GX2CrNiMoCuN 25-6-3-3 grade. The material for research was the above-mentioned cast steel with a chemical composition compliant with the relevant PN-EN 10283 standard, but melted at the lowest standard allowable concentration of alloying additives (some in short supply and expensive), i.e. Cr, Ni, Mn, Mo, Cu and N. The analysis of the crystallization process was performed based on the DTA (Derivative Thermal Analysis) method for a stepped casting with a thickness of individual steps of 10, 20, 40 and 60 mm. The influence of wall thickness was also taken into account in the cast steel microstructure testing, both in the as-cast state and after solution heat treatment. The phase composition of the cast steel microstructure was determined by using an optical microscope and X-ray phase analysis. The analysis of test results shows that the crystallization of tested cast steel uses the ferritic mechanism, while austenite is formed as a result of solid state transformation. The cast steel under analysis in the as-cast state tends to precipitate the undesirable σ-type Fe-Cr intermetallic phase in the microstructure, regardless of its wall thickness. However, the casting wall thickness in the as-cast state affects the austenite grain size, i.e. the thicker the casting wall, the wider the γ phase grains. The above-mentioned defects of the tested duplex alloy cast steel microstructure can be effectively eliminated by subjecting it to heat treatment of type hyperquenching.

7

Wybrane zagadnienia biomineralogii

Pawlikowski Maciej

Przegląd Geologiczny

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2022

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Vol. 70, nr 11

834--839

EN

Biomineralogy is the science between mineralogy, biology, medicine and biochemistry. It is focused on problems concerning mineralization of tissue and organs of human, animals and flora. It concerns interaction between mineral and biological tissue, as well as between biochemical components of living organism. These processes are important for good functioning of organs and human life.

8

Parafina LTP 53/35 jako potencjalny materiał magazynujący ciepło (PCM)

Ksionek Dariusz

Instal

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2021

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nr 11

20--24

PL

W artykule przedstawiono analizę możliwości wykorzystania parafiny LTP 53/35 produkowanej przez firmę Polwax pod kątem jej wykorzystania jako materiału magazynującego ciepło tzw. PCM. Badania wykonano przy użyciu różnicowej kalorymetrii skaningowej DSC, która jest powszechnie wykorzystywana w badaniach materiałów PCM. Potencjał do magazynowania ciepła parafiny określono na podstawie porównania jej z wodą, która jest powszechnie używana w magazynach zarówno ciepła jak i chłodu.

EN

The article contains an analysis of potential to heat storage of paraffin LTP 53/35 Polwax production. For this study one of the thermal analysis methods was used - Differential Scanning Calorimetry (DSC) which is frequently used to study phase change materials. The potential to heat accumulation of the investigated paraffin has been determined in comparison to heat storage potential of water, which is widely used in heat and cold storage.

9

Specjalistyczna zaprawa mineralna REBET A – doskonały środek do napraw obiektów hydrotechnicznych

Buczkowski Wiesław, Szymczak-Graczyk Anna

Przegląd Budowlany

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2020

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R. 91, nr 10

41--43

10

Thermal performances and optical property of poly(L-lactic acid) under the influence of N,N’-dodecanedioic bis(3-phenylpropionic acid) dihydrazide as a crystallization promoter

Yang Xiao-Yu, Zhao Li-Sha, Cai Yan-Hua, Zhao Jie, Wang Lin, Ma Xiao-Li

Polimery

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2020

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T. 65, nr 7-8

523--532

EN

Poly(L-lactic acid) (PLLA) as an important biodegradable polymer suffers from slow crystallization rate and poor heat resistance. An organic compound N,N’-dodecanedioic bis(3-phenylpropionic acid) dihydrazide (BHADD) was synthesized to evaluate its general influences on the physical properties of PLLA. The melt-crystallization process indicated that BHADD could serve as a heterogeneous nucleating agent for improving the crystallization of PLLA, and PLLA/1%BHADD exhibited the sharpest melt-crystallization peak located at the highest temperature, as well as an increase of cooling rate weakened the crystallization ability of BHADD-nucleated PLLA. And the final melting temperature also displayed the significant effect on the crystallization process of PLLA. For the cold-crystallization process, both BHADD concentration and heating rate affected the cold-crystallization behavior of PLLA/BHADD, the increasing of BHADD concentration caused the cold-crystallization peak to shift to the lower temperature; in contrast, a higher heating rate during heating leaded to the peak’s shift toward the higher temperature because of the thermal inertia. The melting behavior of PLLA/BHADD depended on the crystallization temperatures and heating rates, and the double melting peaks were attributed to the melting-recrystallization. Thermal decomposition experiment showed all PLLA/BHADD samples as the pure PLLA only exhibited one thermal decomposition stage, but PLLA/BHADD had a lower thermal stability than the pure PLLA. Additionally, the addition of BHADD seriously decreased the light transmittance of PLLA.

PL

Poli(kwas L-mlekowy) (PLLA) to ważny biodegradowalny polimer charakteryzujący się małą szybkością krystalizacji i słabą odpornością na ciepło. Dihydrazyd kwasu bis(3-fenylopropiono) N,N'-dodekanodiowego (BHADD) zsyntetyzowano w celu oceny jego wpływu na właściwości fizyczne PLLA. Przebieg procesu krystalizacji ze stopu świadczy o tym, że BHADD może służyć jako heterogeniczny środek zarodkujący zwiększający szybkość krystalizacji PLLA. Mieszanina PLLA/1% mas. BHADD wykazywała najostrzejszy pik krystalizacji ze stopu zlokalizowany w zakresie najwyższej temperatury, a jednocześnie większą szybkość chłodzenia osłabiającą zdolność krystalizacji PLLA zarodkowanej BHADD. Również końcowa temperatura topnienia w istotnym stopniu wpływała na proces krystalizacji PLLA. W procesie krystalizacji na zimno zarówno stężenie BHADD, jak i szybkość ogrzewania oddziaływały na zachowanie PLLA/BHADD podczas krystalizacji, zwiększenie stężenia BHADD powodowało przesunięcie piku krystalizacji na zimno w kierunku niższej temperatury, natomiast większa szybkość ogrzewania prowadziła do, spowodowanego bezwładnością cieplną, przesunięcia piku krystalizacji na zimno w kierunku wyższej temperatury. Zachowanie PLLA/BHADD podczas topnienia zależało od temperatury krystalizacji i szybkości ogrzewania, a drugi pik topnienia przypisano procesowi rekrystalizacji. Badany przebieg rozkładu termicznego świadczy, że wszystkie próbki PLLA/BHADD, tak jak czysty PLLA, wykazywały tylko jeden etap rozkładu termicznego, mieszanina PLLA/BHADD charakteryzowała się jednak mniejszą stabilnością termiczną niż czysty PLLA. Dodatek BHADD w znacznym stopniu zmniejszył przepuszczalność światła PLLA.

11

The effect of thermal treatment of the melt before crystallization on the structure and properties of castings

Kondratyuk S. Ye., Veis V. I., Parkhomchuk Z. V.

Archives of Materials Science and Engineering

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2020

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Vol. 104, nr 1

23--29

EN

Purpose: The aim of the proposed research is to investigate the influence of temperature and duration of isothermal melt processing on structural characteristics of castings in connection with technological background of charge metal. Design/methodology/approach: Ferrous and non-ferrous alloys were obtained by remelting a charge with a dispersion-structured structure (which was ensured by high- speed crystallization). Remelting was carried out at different temperatures of overheating of the melt over the liquidus with different isothermal exposure at these temperatures. Experimental castings were crystallized under normal conditions. It was studied a change of structure formation and mechanical characteristics depending on the temperature and duration of thermal treatment of the melt before crystallization. Findings: It is established that isothermal treatment of the melt at the overheating of the liquid metal above a certain equilibrium temperature of the micro-inhomogeneous melt (Te) causes a gradual loss of hereditary characteristics of the original charge metal, increase of the chemical homogeneity of the melt and the formation of crystallization and formation a corresponding change in the mechanical properties of castings. Research limitations/implications: The results can be complemented by studies of the effect of thermal treatment in the temperature range of crystallization. Practical implications: The results can be used to select the optimal heat treatment during remelting and, accordingly, the mechanical properties of the resulting casting. Originality/value: The obtained results testify to the predominant influence of temperature on the dispersion of the cast structure of steels, given the duration of technological operations of preparation and casting of steels in the manufacture of castings in industrial conditions.

12

Phase Transformation Analysis of the Amorphous Mg72Zn24Ca4 Alloy

Lelito J.

Archives of Foundry Engineering

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2020

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Vol. 20, iss. 3

21--24

EN

The paper presents research of metallic glass based on a Mg72Zn24Ca4 alloy. Metallic glass was prepared using induction melting and further injection on a spinning copper wheel. The X-ray diffractometer and differential scanning calorimeter (DSC) were used to investigate the phase transformation of the amorphous ribbon. The heat released in the crystallization process, during isothermal annealing, based on the differential scanning calorimeter investigation, was determined to be 166.18 Jg-1. The effect of isothermal annealing temperature on the kinetics of the amorphous alloy crystallization process using differential scanning calorimeter was investigated. For this purpose, two isothermal annealing temperatures were selected. The incubation time decreases as the temperature of the isothermal annealing increases from 300 to 252 seconds. The same relationship is visible in the case of duration of the phase transformation, which also decreases as the temperature of the isothermal annealing increases from 360 to 228 seconds. The obtained results show a significant influence of isothermal annealing temperature on the degree of phase transformation.

13

Crystallization Behavior and Properties of Hypereutectic Al-Si Alloys with Different Iron Content

Deev V., Prusov E., Prikhodko O., Ri E., Kutsenko A., Smetanyuk S.

Archives of Foundry Engineering

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2020

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Vol. 20, iss. 4

101--107

EN

Understanding the influence of iron impurity on the formation of the structure and the properties of hypereutectic aluminum-silicon alloys are important for achieving the required quality of castings, especially those obtained from secondary materials. In the present work, the influence of different iron contents (0.3, 1.1, and 2.0 wt.%) on the crystallization process, microstructure and mechanical properties of the Al-15% Si alloy was studied. It is shown that the presence of iron impurity in the Al-15% Si alloy leads to increasing the eutectic crystallization time from 6.2 to 7.6 s at increasing the iron content from 0.3 wt.% to 1.1 wt.%, changing the structure of the alloy eutectic in the solid state. The primary silicon and β-Al5SiFe phase coexist in the structure of the Al-15% Si alloys at a temperature below 575°C in the range of iron concentrations from 0 to 2 wt.% in equilibrium conditions. In the experimental alloys structure, the primary crystals of the β-phase were metallographically detected only in the alloys containing 1.1 and 2 wt.% of iron impurity. Increase of the iron content up to 2 wt.% significantly reduces the mechanical properties of the Al-15% Si alloy due to the formation of large platelet-like inclusions of β-Al5SiFe phase.

14

Compacted Graphite Iron with the Addition of Tin

Gumienny G., Kurowska B., Fabian P.

Archives of Foundry Engineering

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2020

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Vol. 20, iss. 3

15--20

EN

The paper presents the effect of tin on the crystallization process, microstructure and hardness of cast iron with compacted (vermicular) graphite. The compacted graphite was obtained with the use of magnesium treatment process (Inmold technology). The lack of significant effect of tin on the temperature of the eutectic transformation has been demonstrated. On the other hand, a significant decrease in the eutectoid transformation temperature with increasing tin concentration has been shown. It was demonstrated that tin narrows the temperature range of the austenite transformation. The effect of tin on the microstructure of cast iron with compacted graphite considering casting wall thickness has been investigated and described. The carbide-forming effect of tin in thin-walled (3 mm) castings has been demonstrated. The nomograms describing the microstructure of compacted graphite iron versus tin concentration have been developed. The effect of tin on the hardness of cast iron was given.

15

Impact of mechanical vibrations introduced by up blasting on the structure and hardness of welds on P235GH steel during MAG welding process

Krajewski Arkadiusz, Kołodziejczak Paweł, Wang Xiaoming

Welding Technology Review

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2019

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R. 91, nr 12

25--32

EN

This article discusses the effects of surfacing with the introduction of mechanical vibrations into the material using shot blasting. It does not require a rigid attachment of the vibrating system to the base material, and vibrations are introduced as a result of supplying energy of collision of the shot with the parent material. The effect of introducing mechanical vibrations through shot blasting during welding of P235GH steel on the structure and hardness of obtained structures was described. Comparative results of tests revealing the basic differences in the structural structure and hardness of reached welds without shot blasting and with its participation were presented. As a result of the conducted research, differences in the structural structure of the welds were shown and it was shown that shot blasting is an effective and alternative method of introducing mechanical vibrations supporting welding processes.

PL

W niniejszym artykule omówiono efekty napawania z wprowadzaniem drgań mechanicznych do materiału z wykorzystaniem śrutowania. Nie wymaga ona sztywnego zamocowania układu drgającego do materiału podstawowego, a drgania wprowadzane są w wyniku dostarczania energii zderzenia śrutu z podłożem. Opisano wpływ wprowadzania drgań mechanicznych poprzez śrutowanie w czasie napawania stali P235GH na strukturę i twardość uzyskanych struktur. Zaprezentowano porównawcze wyniki badań ujawniających podstawowe różnice w budowie strukturalnej i twardości uzyskanych napoin bez śrutowania oraz z jego udziałem. W wyniku przeprowadzonych badań wykazano różnice w budowie strukturalnej napoin i pokazano, że śrutowanie stanowi efektywną i alternatywną metodę wprowadzania drgań mechanicznych wspomagających procesy spawalnicze.

16

Wpływ manganu na ograniczenie negatywnego oddziaływania żelaza w stopach Al-Si

Piątkowski Jarosław, Czerepak Mateusz, Wieszała Robert

Rudy i Metale Nieżelazne Recykling

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2019

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R. 64, nr 1

26--32

PL

W pracy przedstawiono badania wpływu dodatku manganu (0,6 i 1,2%mas.) na przebieg procesu krystalizacji i kształtowanie struktury okołoeutektycznego siluminu EN AC-43000. Stwierdzono, iż dodatek Mn powoduje zanik niekorzystnej kruchej fazy β-Al5FeSi na korzyść fazy α-Al15(FeMn)3Si2, która krystalizuje w postaci zwartych, równomiernie rozłożonych w osnowie roztworu stałego a(Al) wielościennych wydzieleń o wymiarach ok. 7–8 mm. Zmiana niekorzystnej morfologii kruchych eutektyk zawierających żelazo przekłada się na niewielki wzrost właściwości mechanicznych, bez pogorszenia plastyczności stopów Al-Si-Mg-Mn.

EN

The paper presents studies on the effect of manganese addition (0.6 and 1.2% by mass) on the course of the crystallization process and shaping the approximate structure of the silicone EN AC-43000. It was found that the addition of Mn causes the disappearance of the disadvantageous fragile β-Al5FeSi phase in favor of the α-Al15(FeMn)3Si2phase, which crystallizes in the form of compact, uniformly distributed solid matrix a(Al) polyhedral particles with dimensions of approx. 7–8 mm. A change in the unfavorable morphology of brittle iron-containing eutectics translates into a small increase in mechanical properties without deterioration of the Al-Si-Mg-Mn alloys.

17

Silne efekty entropowe orientacji molekularnej w kinetyce krystalizacji polimerów

Ciupak Marcelina, Misztal-Faraj Beata, Pęcherski Ryszard B.

Przemysł Chemiczny

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2019

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T. 98, nr 11

1760--1764

PL

Obliczono i przedyskutowano wpływ orientacji molekularnej oraz temperatury na szybkość nukleacji i wzrostu kryształów ze wskazaniem na rolę entropii w kinetyce krystalizacji polimerów. W celu określenia efektów entropowych w całym zakresie orientacji molekularnej wywołanej naprężeniami rozciągającymi zastosowano dwa przybliżenia statystyki molekularnej. Badania doświadczalne kinetyki krystalizacji orientowanej przeprowadzono dla orientowanej włókniny z polilaktydu (PLLA) oraz nieorientowanego granulatu PLLA jako przykładowego polimeru, z wykorzystaniem różnicowego kalorymetru skaningowego DSC. Przedstawiono znaczny wpływ orientacji molekularnej na szybkość nukleacji, wzrostu kryształów i szybkość krystalizacji, wynikający ze spadku entropii fazy amorficznej w warunkach orientacji. Ujęte jest to w rozszerzonych modelach Hoffmana i Lauritzena oraz Avramiego i Evansa dla orientowanej krystalizacji i w eksperymentalnych wynikach badań kalorymetrycznych DSC.

EN

Effect of mol. orientation and temp. on the nucleation and crystal growth rates of polymers were calcd. and discussed to indicate the role of entropy in the kinetics of its crystn. Two approximations of mol. statistics were used to det. the entropic effects in the entire range of mol. orientation produced by tensile stresses. The exp. investigations on the oriented crystn. kinetics of polylactide nonwoven fibres and unoriented pellets were carried out by differential scanning calorimetry. High effects of the mol. orientation in the entropy strongly affecting the nucleation and crystal growth rates, as well as the crystn. rate were shown based on the Hoffman-Lauritzen and Avrami-Evans models.

18

Opadanie zarodków krystalizacji pochodzących z zapraw AITi5B w kąpieli metalowej podeutektycznych siluminów – skutki procesu

Janusz Arkadiusz, Zych Jerzy

Przegląd Odlewnictwa

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2019

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Vol. 69, nr 1-2

10--15

PL

W artykule skoncentrowano się na słabo rozpoznane zjawisko opadania w kąpieli metalowej heterogenicznych zarodków pierwotnej krystalizacji podeutektycznych stopów Al-Si, którymi są borki tytanu TiB2 pochodzące z zapraw AlTi5B. Badaniami objęto pięć zapraw rynkowych. Wykazano, iż w przypadku pozostawienia metalu w bezruchu w dłuższym okresie (np. ~ 2godzin) następuje wyraźne zubożenie górnych warstw kąpieli metalowej w cząstki pochodzące z AlTi5B i wzbogacenie w nie dolnych warstw kąpieli. Równolegle w warstwach zubożonych obserwuje się wyraźnie zmniejszenie zdolności do zarodkowania, co prowadzi do tworzenia się struktury gruboziarnistej w odlewach. Do oceny zdolności do zarodkowania wykorzystano próbę zwaną testem pierścienia (ang. Ring Test). Wykazano, iż szybkość procesu opadania cząstek nie jest jednakowa dla badanych zapraw, i może ona stanowić jedno z kryteriów oceny ich przydatności do technologii odlewania, w której są zastosowane podgrzewane kadzie. Ma to m.in. miejsce przy zalewaniu form metalowych sposobem odlewania pod niskim ciśnieniem. Prace realizowano we współpracy trzech jednostek Wydziału Odlewnictwa Akademii Górniczo Hutniczej oraz firm: Technologia i Technika Aluminium Z. Smorawiński (Konin) i firmy Royal Polska sp. z o.o. w Jelczu.

EN

The paper is focused on weakly recognised effect of heterogeneous nuclei of the primary crystallisation of hypoeutectic Al-Si alloys, falling in the metal bath. These nuclei are titanium borides TiB2, originated from AITi5B foundry alloys. Five foundry alloys, available in the market, were tested. It was revealed, that in case of leaving the motionless metal for a longer time (e.g. ~ 2 hours), the upper layers of the metal bath were significantly impoverished of particles originated from AITi5B, while the lower layers were enriched in them. Simultaneously a significant decrease of the nucleation ability was observed in impoverished layers, which led to forming coarse-grained structures in castings. The test, called the Ring Test, was applied for assessing the nucleation ability. It was demonstrated that particles falling rates were not the same for the investigated foundry alloys and could constitute one of the assessment criterion of their suitability in the casting technology, in which heated ladles are applied. This occurs, among others at pouring metal moulds by means of the low pressure die casting. Works were realized in cooperation of three units of the Faculty of Foundry Engineering of AGH University of Science and Technology and Companies: Technology and Aluminium Technique Z. Smorawiński (Konin) and Royal Polska I.I.c. in Jelcz.

19

Structure formation and properties of overheated steel depending on thermokinetic parameters of crystallization

Kondratyuk S. Ye., Veis V. I., Parkhomchuk Z. V.

Journal of Achievements in Materials and Manufacturing Engineering

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2019

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Vol. 97, nr 2

49--56

EN

Purpose: The aim of the proposed research is to investigate the mutual influence of the temperature of an overheated melt and its cooling rate during crystallization on the formation of the cast structure and mechanical properties of structural steels. Design/methodology/approach: Two structural medium-carbon steels were melted in induction furnace and poured from temperatures 1520-1670°C into casting moulds with different heat removal ability. This ensured the crystallization and structure formation of the studied steel castings at cooling rates (Vc) of 5°C/sec (sand-clay mould), 45°C/sec (steel mould), 350°C/sec (water cooled copper mould). It was studied a change of structure formation, mechanical characteristics depending on the temperature-kinetic conditions of the processing of the melt. Based on the processing of the array of obtained experimental data using linear regression analysis and a software package, interpolation models and their graphic images obtained allow a quantitative assessment of the established patterns of structural characteristics and mechanical properties of the studied steels depending on melt temperature (T, °C) and its cooling rate (Vc, °C/sec) during crystallization and structure formation. Findings: Among the technological factors that determine the formation of the cast structure and the mechanical properties of steels, the dominant role is played by the intensity of heat removal during the solidification of castings. The high cooling rate of the melt during crystallization determines an increase in the number of crystallization nuclei due to an increase in the degree of supercooling of the melt, eliminates the negative effect of the high overheating temperature of the metal before casting. Research limitations/implications: In the future, the results can be complemented by studies of the influence of the duration of isothermal exposure of the melt at different temperatures of superheating and cooling conditions. Practical implications: The obtained mathematical models (regression equations) that determine the mutual influence of the cooling rate and the temperature of the melt overheating on the structure and mechanical properties of the studied steels make it possible to obtain steel castings with predetermined properties at the level of properties of wrought steel of similar chemical composition. Originality/value: Interpolation models that allow a quantitative assessment of the established patterns of structural characteristics and mechanical properties of the studied steels depending on the melt temperature (T, °C) and its cooling rate (Vc, °C/sec) during crystallization and structure formation are obtained.

20

Mikrostruktura złącza spawanego

Blicharski Marek, Dymek Stanisław

Hutnik, Wiadomości Hutnicze

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2019

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Vol. 86, nr 4

108--116

PL

Mikrostruktura złącza spawanego cechuje się bardzo dużą niejednorodnością na jego przekroju, a ponadto jest zależna od materiału spawanego, użytego spoiwa oraz od zastosowanej metody i warunków spawania. Ze względu na dużą różnorodność materiałów spawanych oraz parametrów spawania w artykule przedyskutowano tylko podstawowe zasady tworzenia się mikrostruktury spoiny. Szczególną uwagę zwrócono na redystrybucję pierwiastków rozpuszczonych oraz na kształt i stabilność frontu krystalizacji podczas krzepnięcia spoin. Scharakteryzowano poszczególne strefy złącza spawanego oraz omówiono szczegółowo czynniki wpływające na mikrostrukturę spoiny oraz strefy wpływu ciepła.

EN

Weld microstructure observed on the weld cross-section is highly inhomogeneous and depends on joined materials, filler metals, welding methods as well welding conditions. Due to large variety of welded materials and applied welding parameters the paper discusses only the basic principles that govern the evolution of microstructure during welding. In particular, the redistribution of alloying elements during solidification as well as the shape and stability of the crystallization front were addressed in detail. Also, particular regions of weld were described in a thorough manner with an emphasis on factors influencing the weld microstructure.