Wyniki wyszukiwania - Biblioteka Nauki

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A New Technology of TRIAD Cement-Free Castables – Practical Aspects

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Cygan B. , Dorula J. , Jezierski J.

Archives of Foundry Engineering

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2021

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tom Vol. 21, iss. 2

94--98

EN

The article presents the new technology of the refractory materials used for the ladles and pouring devices. The aim for solving the majority of the problems that originated from the refractory lining was to develop the group of cement-free TRIAD products by Vesuvius company. The cement-free setting system in the TRIAD products eliminates calcium oxide (CaO) that occurs in low and extra low cement concretes resulting in its higher strength at higher temperatures. The features of the new cement-free castables were described. One of the most unique features of this technology is the porous material structure. Small venting microchannels are formed during the concrete setting process. These micro-channels allow for removing water vapor from the lining without affecting its refractory properties. On the other hand, the diameter of pores is so low that it disallows the penetration of slag and metal into the lining, extends its operating life at the same time facilitates cleaning and removing build-ups. The procedure of the preparation of these materials, as well as the method of building of the lining, were presented. An example of the practical use of these materials in the ductile cast iron foundry was presented, showing the advantages of the new refractory materials over the traditional ones.

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Scanning Electron Microscopy as a Tool for Castings Quality Analysis

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Jezierski J. , Dojka M. , Stawarz M. , Dojka R.

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2022

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tom Vol. 22, iss. 1

53--61

EN

Nowadays, the best castings’ manufacturers have to meet very demanding requirements and specifications applicable to mechanical properties and other characteristics. To fulfill those requirements, more and more sophisticated methods are being used to analyze the internal quality of castings. In many cases, the commonly used Non-Destructive Methods, like X-ray or ultrasonic testing, are not enough to ensure precise and unequivocal evaluation. Especially, when the properties of the casting only slightly fail the specification and the reasons for such failures are very subtle, thus difficult to find without the modern techniques. The paper presents some aspects of such an approach with the use of Scanning Electron Microscopy (SEM) to analyze internal defects that can critically decrease the performance of castings. The paper presents the so-called bifilm defects in ductile and chromium cast iron, near-surface corrosion caused by sulfur, micro-shrinkage located under the risers, lustrous carbon precipitates, and other microstructure features. The method used to find them, the results of their analysis, and the possible causes of the defects are presented. The conclusions prove the SEM is now a powerful tool not only for scientists but it is more and more often present in the R&D departments of the foundries.

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Various Aspects of Application of Silicon Carbide in the Process of Cast Iron Melting

88%

Janerka K. , Kostrzewski Ł. , Stawarz M. , Jezierski J. , Szajnar J.

Archives of Metallurgy and Materials

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2022

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tom Vol. 67, iss. 3

1093--1098

EN

The article discusses benefits associated with the use of silicon carbide in the process of melting gray cast iron and ductile cast iron in induction electric furnaces. It presents the analysis of the impact of various charge materials and the addition of a variable amount of SiC and FeSi to the fixed charge when melting cast iron of grades GJS 400-15 and GJS 500-7 on mechanical properties and microstructure. Moreover, the article includes an analysis of the efficiency of carburization and the increase in the content of silicon during the application of SiC. The article also presents the results of the study of primary modification using silicon carbide at the minimum temperature of Temin eutectic and Tsol solidus. Based on analysis of the literature, conducted research, and calculations, it was found that the addition of silicon carbide has a beneficial impact on the properties of melted cast iron. The addition of SiC in the charge increases the content of C and Si without increasing the amount of contaminations. The addition of SiC at reduced pig iron presence in the charge decreases production costs, while the use of SiC as an inoculant increases both Temin and Tsol, which is beneficial from the point of view of cast iron nucleation.

4

Zastosowanie procesu AOD w produkcji odlewów staliwnych do pracy w ekstremalnych warunkach eksploatacji

75%

Kostrzewa K. , Kutera W. , Zdonek B. , Żak A. , Szypuła I. , Jezierski J.

Journal of Metallic Materials

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2020

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tom Vol. 72, no. 2

53--62

PL

Wymagania do eksploatacji odlewów staliwnych w ekstremalnych warunkach dotyczą gatunków od nisko- do wysokostopowych wytwarzanych z zastosowaniem pozapiecowej obróbki staliwa w celu uzyskania bardzo dokładnej regulacji składu chemicznego oraz zapewnienia bardzo wysokiej czystości staliwa. Optymalnym rozwiązaniem dla warunków odlewni było zastosowanie konwertora AOD (po raz pierwszy w Polsce) do rafinacji staliwa spuszczanego z pieców: łukowego i indukcyjnego. Zbadano pod względem jakości odlewy ze staliwa niskostopowego do pracy w niskich temperaturach, staliwa wysoko topowego, martenzytycznego do pracy w wysokich temperaturach i wysokostopowego duplex, do pracy w środowiskach wysoce korozyjnych. Zastosowanie procesu AOD zapewni odlewni znaczne powiększenie portfela zamówień, zarówno krajowych jak i na eksport, przy równoczesnym zwiększeniu rentowności produkcji odlewni.

EN

Requirements for the use of steel castings in extreme conditions apply to grades from low- to high-alloyed produced with the use of secondary treatment of cast steel in order to obtain very accurate regulation of the chemical composition and to ensure very high purity of the cast steel. The optimal solution for foundry conditions was the use of an AOD converter ( for the first time in Poland) for the refining of steel cast from electric arc furnace. In terms of internal quality, low-alloy cast steel castings for low temperature operation, high-alloy martensitic cast steel for high temperature operation and high-alloy duplex casting for high corrosive environments were tested. The application of the AOD process will provide the foundry with a significant increase in its domestic and international portfolio, while increasing the profitability of the foundry’s production.