Effect of graphite shape on the Corrosion of Grey Cast Iron in phosphoric acid

Abstract

Grey cast iron (3.4 %C-2.7 %Si-0.4 %Mn-0.05 %P-0.008 %S) with different morphology of graphite and different amount of ferrite, pearlite and eutectic phases has been subjected to corrosion and electrochemical tests in phosphoric acid solution, simulating the oxidized engine oil. The difference in the cathodic process and corrosion of studied materials has been mainly attributed to the variation of ferrite and pearlite volume fraction and to the presence of eutectic phases In the matrix of metals with different graphite shape. The possible assistance of the additions of Ce and Sn modificators on electrochemical behavior of cast iron has been discussed.Corrosion process accompanied by the hydrogen evolution leads to the formation of hydrogen induced cracks at the sharp edges of the graphite particles. In vermicular cast iron, hydrogen cracks form the spatial network causing the falling off some parts of metal and thus accelerating the degradation of this material under the corrosion-erosion conditions. An GuReisen (3,4%C-2,7 %Si-0,4 %Mn-0,05 %P4,008 %S) mit unterschiedlicher Graphitmorphologie und verschiedenen Gehalten an Ferrit, Perlit und eutektischen Phasen wurden in einer Phosphorsaurelosung, die oxidiertes Maschineno1 simulierte, Korrosionsversuche sowie elektrochemische Untersuchungen durchgefiihrt. Der an den untersuchten Werkstoffen festgestellte Unterschied in der kathodischen Reaktion und der Korrosion ist im wesentlichen auf die Variation der Volumenanteile an Ferrit und Perlit sowie das Vorhandensein von eutektischen Phasen in der Metallmatrix mit verschiedener Graphitform zuriickzufiihren. Der mogliche EinfluR von Zusatzen von Ce und Sn Modifikatoren auf das elektrochemische Verhalten von GuBeisen wird diskutiert.Der KorrosionsprozeR, begleitet durch Wasserstoffentwicklung, fiihrt zur Bildung von wasserstoffinduzierten Rissen an den scharfen Ecken der Graphitteilchen. In VermicularguReisen bilden Wasserstoffrisse ein raumliches Netzwerk, was dazu fuhrt, daRTeile des Metalls herausfallen, wodurch die Schadigung dieses Werkstoffs unter den Korrosions-Erosions-Bedingungen beschleunigt wird.

Improving the corrosion and wear resistance of grey cast iron components by surface welding with duplex stainless steel using regulated gas metal arc welding: Influence of dilution on corrosion properties

“…The test zone of the lamellar grey cast iron is completely worn by corrosion, Figure 15a The lamellar grey cast iron corroded severely, Figure 16. Because of a potential difference between the two phases, the less noble ferritic-pearlitic matrix in contact with the more noble carbon flakes corrodes preferentially, Figure 16b [40,25]. The carbon flakes lose stability in the matrix and dissolve into the medium.…”

Niobium addition effect in molds at last cooling step on EN-GJL250 gray cast iron: Microstructural changes and electrochemical behavior

“…E-mail: kassiazzoug@gmail.com Overseas Foundry are in relation to the nucleation process and morphological transformations of graphite. The latter is dependent on the tensile strength of the cast iron (cracking sites) and the corrosion behavior in some corrosive environments [7,10,[19][20][21][22] .…”

“…Lunarska [7] studied the effect of the graphite form on corrosion of gray cast iron in acid phosphoric (H 3 PO 4 ). He concluded that the vermicular form of graphite is beneficial to the mechanical and tribological properties.…”

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I t is well established that the variety of applications of cast iron is attributed to the presence of chemical elements in the solid solution as interstitial or substitutional form, such as so-called addition elements Ni, Cu, Ti, Cr, V and Nb [1][2][3][4] , and inoculation elements Al, Si, Ca, Sr, Mn, Zr, P, Sn and Ce [5][6][7] .In the foundry, additions are done by controlling the

Abstract:The purpose of this study was to determine the impact of niobium addition as an inoculation element on the microstructure and electrochemical properties of EN-FGL250 gray cast iron. Niobium additions are in a powder form and have a 0.5 mm particle size at dfferent proportions of 1wt.% and 3wt.%.

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“…I t is well established that the variety of applications of cast iron is attributed to the presence of chemical elements in the solid solution as interstitial or substitutional form, such as so-called addition elements Ni, Cu, Ti, Cr, V and Nb [1][2][3][4] , and inoculation elements Al, Si, Ca, Sr, Mn, Zr, P, Sn and Ce [5][6][7] .…”