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Abstract

The article presents the results of research concerning AlCu4MgSi alloy ingots produced using horizontal continuous casting process under variable conditions of casting speed and cooling liquid flow through the crystallizer. The mechanical properties and structure of the obtained ingots were correlated with the process parameters. On the basis of the obtained results, it has been shown that depending on the cooling rate and the intensity of convection during solidification, significant differences in the mechanical properties and structure and of the ingots can occur. The research has shown that, as the casting speed and the flow rate of the cooling liquid increase, the hardness of the test samples decreases, while their elongation increases, which is related to the increase of the average grain size. Also, the morphology of the intermetallic phases precipitations lattice, as well as the centerline porosity and dendrite expansion, significantly affect the tensile strength and fracture mechanism of the tested ingots.

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Authors and Affiliations

P.M. Nuckowski
T. Wróbel
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Abstract

The article presents results of research on the influence of variable parameters of horizontal continuous casting on the structure of AlCu4MgSi (EN AW-2017A) alloy ingots. The special character of the process allows for a continuous change of some of its parameters, namely, of the casting speed and of the rate of the cooling fluid flow thorough the crystallizer. These parameters have a significant impact on the crystallization process of the liquid metal. Depending on the cooling rate, intensity of the convection inside the solidifying alloy, and its chemical composition, there may arise some differences in the structure of the cast. In this study, ingots obtained at different casting speeds have been analyzed. The research methodology, based on light microscopy and electron microscopy (SEM), as well as energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), allowed for a thorough examination of the structure of the studied materials. The results were shown that an increase in the ingot casting speed leads to an increase in the average grain surface area.

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Authors and Affiliations

T. Wróbel
P.M. Nuckowski
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Abstract

The paper presents the research results of the influence of the precipitation hardening on hardness and microstructure of selected Al-Si and Al-Cu alloys obtained as 30 mm ingots in a horizontal continuous casting process. The ingots were heat treated in process of precipitation hardening i.e. supersaturation with subsequent accelerated or natural ageing. Moreover in the range of the study it has been carried out investigations of chemical constitution, microscopic metallographic with use of scanning electron microscope with EDS analysis system, and hardness measurements using the Brinell method. On basis of obtained results it has been concluded that the chemical constitution of the investigated alloys enables to classify them into Al alloys for the plastic deformation as EN AW-AlSi2Mn (alternatively cast alloy EN AC-AlSi2MgTi) and as EN AW-AlCu4MgSi (alternatively cast alloy EN AC-AlCu4MgTi) grades. Moreover in result of applied precipitation hardening has resulted in the precipitation from a supersaturated solid solution of dispersive particles of secondary phases rich in alloying element i.e. Si and Cu respectively. In consequence it has been obtained increase in hardness in case of AlSi2Mn alloy by approximately 30% and in case of AlCu4MgSi alloy by approximately 20% in comparison to the as-cast state of continuous ingots.
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Authors and Affiliations

T. Wróbel
P.M. Nuckowski
P. Jurczyk
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Abstract

The article presents the results of research concerning to AlCu4MgSi alloy ingots produced using horizontal continuous casting process. The presented research was focused on the precise determination of phase composition of the precipitates formed during the solidification of ingots and the analysis of their thermal stability. In order to assess the morphology of precipitates in the AlCu4MgSi alloy, data obtained by using a computer simulation of thermodynamic phenomena were compiled with results obtained using advanced research techniques, i.e. High-temperature X-ray diffraction (HT-XRD), SEM-EDS, Thermal and derivative analysis (TDA) and Glow discharge optical emission spectroscopy (GD OES). SEM observations and analysis of chemical composition in micro-areas showed that the precipitates are mainly intermetallic θ-Al2Cu and β-Mg2Si phases, and also presence of Al19Fe4MnSi2 intermetallic phase was confirmed by X-ray diffraction studies. Based on the prepared Thermo-Calc simulation data, high-temperature X-ray diffraction measurements were conducted.

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Authors and Affiliations

P.M. Nuckowski
M. Kondracki
T. Wróbel
ORCID: ORCID
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Abstract

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.
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Bibliography

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[8] Šenberger, J., Pernica, V., Kaňa, V. & Záděra, A. (2018). Prediction of ferrite content in austenitic Cr-Ni steel castings during production. Archives of Foundry Engineering. 18(3), 91-94. https://doi.org/10.24425/123608.
[9] Kaňa, V., Pernica, V., Záděra, A. & Krutiš, V. (2019). Comparison of methods for determining the ferrite content in duplex cast steels. Archives of Foundry Engineering. 19(2), 85-90. https://doi.org/10.24425/afe.2019.127121.
[10] Yamamoto, R., Yakuwa, H., Miyasaka, M. & Hara, N. (2019). Effects of the α/γ-phase ratio on the corrosion behavior of cast duplex stainless steel. Corrosion. 76(9), 815-825. https://doi.org/10.5006/3464.
[11] Jurczyk, P., Wróbel, T. & Baron, C. (2021). The influence of hyperquenching temperature on microstructure and mechanical properties of alloy cast steel GX2CrNiMoCuN 25-6-3-3. Archives of Metallurgy and Materials. 66(1), 73-80. https://doi.org/10.24425/amm.2021.134761.
[12] Kalandyk, B., Zapała, R. & Pałka, P. (2022). Effect of isothermal holding at 750 °C and 900 °C on microstructure and properties of cast duplex stainless steel containing 24% Cr-5% Ni-2.5% Mo-2.5% Cu. Materials. 15(23), 1-17. https://doi.org/10.3390/ma15238569.
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Authors and Affiliations

T. Wróbel
1
ORCID: ORCID
P. Jurczyk
1
ORCID: ORCID
C. Baron
1
ORCID: ORCID
P. Nuckowski
2
ORCID: ORCID

  1. Silesian University of Technology, Department of Foundry Engineering, Towarowa 7, 44-100 Gliwice, Poland
  2. Silesian University of Technology, Materials Research Laboratory, Konarskiego 18a, 44-100 Gliwice, Poland

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