Nonmetallic oxide inclusions and oxygen in the vacuum-jet refining of steel

Gulyakov, V. S.; Vusikhis, A. S.; Kudinov, D. Z.

doi:10.3103/s0967091212110034

Cited by 15 publications

(16 citation statements)

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“…Despite vast progress in manufacturing technologies, non-metallic inclusions have not been completely eliminated from steel [12][13][14]. Their negative impact on fatigue strength has been widely discussed in the literature [2,15,16], mostly in studies of hard-fatigue steels with low plasticity and inclusions larger than 5 µm.…”

Section: Introductionmentioning

confidence: 99%

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The Effect of Fine Non-Metallic Inclusions on the Fatigue Strength of Structural Steel

Lipiński¹,

Wach²

2015

Archives of Metallurgy and Materials

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The article discusses the results of a study investigating the effect of the number of fine non-metallic inclusions (up to 2 µm in size) on the fatigue strength of structural steel during rotary bending. The study was performed on 21 heats produced in an industrial plant. Fourteen heats were produced in 140 ton electric furnaces, and 7 heats were performed in a 100 ton oxygen converter. All heats were desulfurized. Seven heats from electrical furnaces were refined with argon, and heats from the converter were subjected to vacuum circulation degassing.Steel sections with a diameter of 18 mm were hardened and tempered at a temperature of 200, 300, 400, 500 and 600• C. The experimental variants were compared in view of the applied melting technology and heat treatment options. The results were presented graphically, and the fatigue strength of steel with a varied share of non-metallic inclusions was determined during rotary bending. The results revealed that fatigue strength is determined by the relative volume of fine non-metallic inclusions and tempering temperature.Keywords: steel, structural steel, non-metallic inclusions, fatigue strength, bending fatigue, bending pendulum W pracy przedstawiono wyniki badań wpływu ilości drobnych wtrąceń niemetalicznych, o wielkości do 2 µm, na wytrzymałość zmęczeniową przy zginaniu obrotowym. Badania prowadzono na 21 wytopach wyprodukowanych w warunkach przemysłowych. 14 wytopów wykonano w piecach elektrycznych o pojemności 140 ton i 7 wytopów w konwertorze tlenowym o pojemności 100 ton. Wszystkie wytopy poddawano odsiarczaniu. 7 wytopów pochodzących z pieca elektrycznego poddawano rafinacji argonem, zaś wytopy z konwertora odgazowaniu próżniowemu.Odcinki ze stali o średnicy 18 mm hartowano i odpuszczano w temperaturach: 200, 300, 400, 500 lub 600 • C. Warianty badań zestawiono uwzględniając technologię wytapiania stali opcje obróbki cieplnej. Wyniki przedstawiono w graficznej postaci uwzględniającej zależności wytrzymałości zmęczeniowej przy obrotowym zginaniu z udziałem objętościowym wtrąceń niemetalicznych. Wykazano, że wytrzymałość zmęczeniowa zależy od objętości względnej drobnych wtrąceń niemetalicznych, oraz temperatury odpuszczania.

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Section: Introductionmentioning

confidence: 99%

“…Non-metallic inclusions are one of the factors that influence the fatigue strength of steel [9][10][11][12]. Despite vast progress in manufacturing technologies, non-metallic inclusions have not been completely eliminated from steel [12][13][14].…”

Section: Introductionmentioning

confidence: 99%

The Effect of Fine Non-Metallic Inclusions on the Fatigue Strength of Structural Steel

Lipiński¹,

Wach²

2015

Archives of Metallurgy and Materials

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“…The content of particles in steel after outside furnance treatment is presented in [40], the structure size in [42] and the analysis of their morphology in [13]. The distances between the impurities on fatigue strength structural steel α were calculated by (1) and arithmetic average impurities space λ were calculated by (2):…”

Section: Methodsmentioning

confidence: 99%

Influence of size and distances between impurities on fatigue strength structural steel for agricultural machines

Lipiński

2018

Engineering for Rural Development

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Abstract. The high-purity low carbon steel properties are influenced by the chemical composition and production technology. The morphology of impurity, its size and content is very important for the quality of high-purity steel. Hard, non-plastic microstructure of steel with impurities as non-metallic inclusions can be one of the factors that influence the fatigue strength of steel. The quantity of non-metallic inclusions results from the content of impurities in the steel, while their size, dispersion, microstructure, phase composition shape and impurity spaces are determined by the course of technological processes in liquid state. The tested material consisted of semi-finished products of highpurity, low-carbon structural steel with: boron, chromium, manganese, molybdenum, nickel and low contents sulfur and phosphorus as impurities. The experimental material obtained in industrial production consisted of structural steel obtained in three series of steel melts in furnaces: electric with desulfurized, electric with desulfurized and next argon-refined and the third series from oxygen converter with vacuum degassed of steel. The technological process consisted of two melting technologies: the first and second in a 140-ton basic industrial arc furnace and the third in a 100-ton oxygen converter. The test specimens were austenitized by treatment at temperature 880 ºC for 30 minutes. Next the samples were cooled in cold water and tempered in different temperatures: 200, 300, 400, 500 and 600 ºC for 120 minutes and cooled on air. The fatigue strength of the samples was tested on a rotary bending machine at a frequency load 6000 rotations per minute. The present work discusses the results of changes in rotary bending fatigue strength of low carbon structural steel hardened and tempered at different temperatures as the influence of size and distance proportions between the impurities of high-purity low carbon steel.Keywords: steel, structural steel, fatigue strength, bending fatigue, impurities. IntroductionThere are many machine elements that work with variable loads. Variable steel load causes material fatigue [1; 3]. Microcrack is formed after crossing the limit of fatigue strength. The microcrack increases along with the lifetime load of the element [4][5][6][7][8]. Low fatigue strength may result in damage to the working element [9-10]. The fatigue cracking results mainly from exceeding the immediate fatigue strength of the material and material imperfection [11][12][13][14][15]. The material imperfection mainly is caused by the production process with the effect on alloy properties in particular fatigue strength [4; 16-18]. Stochastic events are mainly methods allowing to analyse factors for crack of material under the periodically varying loads [10; 19]. The low carbon steels are polycrystalline, consisting of grains with random dimension and shape geometrically separated by grain boundaries often with precipitates forming notches. The grain boundaries themselves often have different properties than the grain t...

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“…Their results set strict criteria as to the allowable steel impurity. In hard steels, reduced mechanical properties at changing loads are unambiguously attributed to non-metallic inclusions [8,[27][28][29][30][31][32][33][34][35][36][37].…”

Section: Introductionmentioning

confidence: 99%

Size of Non-Metallic Inclusions in High-Grade Medium Carbon Steel

Lipiński¹,

Wach²

2014

Archives of Foundry Engineering

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Non-metallic inclusions found in steel can affect its performance characteristics. Their impact depends not only on their quality, but also, among others, on their size and distribution in the steel volume. The literature mainly describes the results of tests on hard steels, particularly bearing steels. The amount of non-metallic inclusions found in steel with a medium carbon content melted under industrial conditions is rarely presented in the literature. The tested steel was melted in an electric arc furnace and then desulfurized and argonrefined. Seven typical industrial melts were analyzed, in which ca. 75% secondary raw materials were used. The amount of non-metallic inclusions was determined by optical and extraction methods. The test results are presented using stereometric indices. Inclusions are characterized by measuring ranges. The chemical composition of steel and contents of inclusions in every melts are presented. The results are shown in graphical form. The presented analysis of the tests results on the amount and size of non-metallic inclusions can be used to assess them operational strength and durability of steel melted and refined in the desulfurization and argon refining processes.

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Nonmetallic oxide inclusions and oxygen in the vacuum-jet refining of steel

Cited by 15 publications

References 1 publication

The Effect of Fine Non-Metallic Inclusions on the Fatigue Strength of Structural Steel

The Effect of Fine Non-Metallic Inclusions on the Fatigue Strength of Structural Steel

Influence of size and distances between impurities on fatigue strength structural steel for agricultural machines

Size of Non-Metallic Inclusions in High-Grade Medium Carbon Steel

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