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Abstract

The article deals with the influence of chemical composition of martensitic stainless steel for castings GXCrNi13-4 (the 1.4317 material) on mechanical properties and structure of as cast steel after heat treatment. Properties of these martensitic stainless steel are heavily influenced by chemical composition and structure of the material after heat treatment. Structure of these steels after quenching is formed with martensite and residual austenite. When tempering the steel the carbon content in martensite is reduced and gently deposited carbides occur. The way of heat treatment has a major impact on structure of martensitic steels with low carbon content and thus on strength, hardness and elongation to fracture of these steels. Chemical composition of the melt has been treated to the desired composition of the lower, middle and upper bounds of the nickel content in the steel within the limits allowed by the standard. Test blocks were gradually cast from the melt. The influence of the nickel equivalent value on structure and properties of the 1.4317 steel was determined from results of mechanical tests.
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Authors and Affiliations

A. Záděra
L. Čamek
V. Kaňa
M. Myška
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Abstract

The aim of the paper is experimental verification of the influence of the composition of the ceramic mixture on the mechanical properties of cast ethyl silicate cores. Cast ceramic cores have a great potential in the production of complex castings, especially in the field of hydropower. However, the disadvantage of the cast ceramic cores is their low strength during cores removing from the core box and handling with them. The research is focused mainly on the possibilities of increasing the handling strength of the cores during removal from the core box and after their ignition. The paper investigates different ways of increasing the strength of cast ceramic cores by adjusting the composition of the ceramic mixture. Further, the research verifies the possibility of increasing the strength of ceramic cores by adding synthetic fibers to the ceramic mixture. The paper also contains the results of measuring the strength of the cores after impregnation with a solution of phosphorous binder and subsequent annealing.
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Bibliography

[1] Cihlář, J. (1993). Hydrolysis and polycondensation of ethyl silicates. 2, Hydrolysis and polycondensation of ETS40 (ethyl silicate 40). Colloids and Surfaces A: Physicochemical and Engineering Aspects. 7093), 253-268. https://doi.org/10.1016/0927-7757(93)80299-T.
[2] Doškář, J. (1976). Production of precision castings. (1st ed.). Prague: SNTL. (in Czech)
[3] Lewis, J.A. (2000). Colloidal processing of ceramics. Journal of the American Ceramic Society. 83(10), 2341-2359. https://doi.org/10.1111/j.1151-2916.2000.tb01560.x.
[4] Raza, N., Raza, W., Madeddu, S., Agbe, H., Kumar, R.V. & Kim, K.H. (2018). Synthesis and characterization of amorphous precipitated silica from alkaline dissolution of olivine. RSC advances. 8(57), 32651-32658. https://doi.org/10.1039/c8ra06257a.
[5] Doškář, J., Kaštánek, O., Gabriel, J., Valihrach, O. (1961). Precision casting in ceramic molds: designed high techn. foundry staff, work. development and research in mechanical engineering. Prague: SNTL. (in Czech).
[6] Wagh, A.S. (2004). Chemically BondedPhosphate Ceramics. 21st Century Materials with Diverse Applications. Oxford: Elsevier. Retrieved March 15, 2022, from https://doi.org/10.1016/B978-008044505-2/50006-5
[7] Wagh, A.S. & Jeong, S.Y. (2003). Chemically bonded phosphate ceramics: i, A dissolution model of formation. Journal of the American Ceramic Society. 83(11). 1838-1844. DOI: https://doi.org/10.1111/j.1151-2916.2003.tb03569.x
[8] Hlaváč, J. (1988). Fundamentals of silicate technology. Prague: SNTL. (in Czech)
[9] Lü, K., Liu, X., Du, Z., & Li, Y. (2016). Bending strength and fracture surface topography of natural fiber-reinforced shell for investment casting process. China Foundry, 13, 211-216. DOI: 10.1007/s41230-016-5100-4.
[10] Lü, K., Liu, X., & Duan, Z. (2018). Effect of firing temperature and time on hybrid fiber-reinforced shell for investment casting. International Journal of Metalcasting. 13(3), 666-673. DOI: 10.1007/s40962-018-0280-x.
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Authors and Affiliations

P. Bořil
1
ORCID: ORCID
V. Kaňa
1
ORCID: ORCID
M. Myška
1
ORCID: ORCID
V. Krutiš
1
ORCID: ORCID

  1. Brno University of Technology, Czech Republic
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Abstract

This work deals with the problem of intermetallic phases in cast standard duplex steel ASTM A890 Gr 4A (generally known as 2205). The investigated steel was subjected to isothermal heat treatment in the range from 595 °C to 900 °C and in the duration from 15 minutes to 245 hours, and was also investigated in terms of anisothermal (natural) cooling after casting into the mould. The precipitation starts at grain boundaries with a consistent ferrite transformation. The work is focused on the precipitation of the sigma phase (σ) and the chi phase (χ). Examination of the microstructure was conducted using light and scanning electron microscopy. Their statistical analysis was carried out using the results of the investigations of precipitation processes in the microstructure, both within the grains and at the grain boundaries. To illustrate this impact, the surface area of precipitates was evaluated. The percentage of these intermetallic phases was calculated by measuring their area using a computer image analysis system. Based on their observations, a combined time-temperature transformation (TTT) diagram with continuous cooling transformation (CCT) curves was created.
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Authors and Affiliations

M. Myška
1
ORCID: ORCID
P. Bořil
1
ORCID: ORCID
V. Krutiš
1
ORCID: ORCID
V. Kaňa
1
ORCID: ORCID
A. Zádĕra
1
ORCID: ORCID

  1. Brno University of Technology, Czech Republic

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