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1

Corrosion Resistance of High-Alloyed White Cast Iron

Kawalec M., Krawiec H.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 1

301--303

EN

The paper presents the results of corrosion resistance tests carried out on high-alloyed white cast iron. Tests were performed in 0.1 M NaCl by the technique of linear voltammetry. The test material was collected from six high-vanadium cast iron melts with a variable content of carbon and vanadium, and thus with different microstructure. Studies have confirmed that the type of crystallised microstructure has a very important effect on the alloy corrosion resistance. The highest corrosion resistance showed the alloy with a ferritic matrix containing the spheroidal precipitates of vanadium carbide VC, while the lowest had the eutectic alloy with a pearlitic matrix.

PL

W pracy przedstawiono wyniki badań odporności na korozję wysokostopowego żeliwa białego. Badania przeprowadzono w 0,1M roztworze NaCl techniką woltamperometrii liniowej. Materiał do badań pobrano z sześciu wytopów żeliwa wysoko-wanadowego o zmiennej zawartości węgla i wanadu, a tym samym o różnej mikrostrukturze. Badania potwierdziły, że rodzaj wykrystalizowanej mikrostruktury ma bardzo istotny wpływ na odporność na korozję stopu. Najwyższą odporność na korozję wykazał stop o osnowie ferrytycznej ze sferoidalnymi wydzieleniami węglików VC, natomiast najniższą - eutektyczny stop o osnowie perlitycznej.

2

Carbide spheroidisation in 100CrMnSi6-4 bearing steel by controlled rolling

Dlouhy J., Hauserova D., Novy Z.

Archives of Materials Science and Engineering

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2014

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Vol. 68, nr 2

87--92

EN

Purpose: This article describes influence of thermomechanical treatment parameters on microstructure and mechanical properties of 100CrMnSi6-4 bearing steel. Design/methodology/approach: Steel properties after accelerated carbide spheroidisation enables machining and cold forming as well as after conventional soft annealing. Apparently, structure after accelerated carbide spheroidisation is significantly finer than after long duration soft annealing – in terms of carbide particles and grain size. That enhances steel hardness and homogeneity of the structure in final state after hardening. Findings: Presented experiment deals with accelerated carbide spheroidisation of 100CrMnSi6-4 bearing steel during final stage of hot rolling. Main purpose is to achieve microstructure consisting of globular carbides and ferritic matrix directly after hot forming. Research limitations/implications: The combination of a suitable forming temperature, an appropriate amount of deformation and a possible reheating lead to globular carbide formation during austenite decomposition instead of cementite lamellae. Originality/value: Experiment results are promising for quenching and tempering in comparison with structure after conventional soft annealing with coarser. Finer ASR structure retains finer austenite grain at quenching temperature and higher dispersion strengthening.

3

Modification of the high-alloyed white cast iron microstructure with magnesium master alloy

Kawalec M.

Archives of Foundry Engineering

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2013

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Vol. 13, iss. 2

71--74

EN

High-vanadium cast iron is the white cast iron in which the regular fibrous \gamma + VC eutectic with the volume fraction of vanadium carbide amounting to about 20% crystallises. This paper presents the results of studies on high-vanadium cast iron subjected to the inoculation treatment with magnesium master alloy. The aim of this operation is to change the morphology of the crystallising VC carbides from the fibrous shape into a spheroidal one. The study also examines the effect of the amount of the introduced inoculant on changes in the morphology of the crystallising VC carbides. To achieve the goals once set, metallographic studies were performed on high-vanadium cast iron of eutectic composition in base state and after the introduction of a variable content of the inoculant. The introduction of magnesium-based master alloy resulted in the expected changes of microstructure. The most beneficial effect was obtained with the introduction of 1.5% of magnesium master alloy, since nearly half of the crystallised vanadium carbides have acquired a spheroidal shape.