Effect of the Al2O3 Content in the Slag on the Chemical Reactions and Nonmetallic Inclusions during Electroslag Remelting

Abstract The service life of roller bearings is extremely sensitive to large and hard nonmetallic inclusions (NMIs), requesting the highest standards in their production. To determine the metallurgical possibilities, the effect of Al2O3 contents between 0 and 33 pct in the remelting slag was investigated by remelting a roller bearing steel in an experimental electroslag remelting (ESR) plant. Thereby, changes in the chemical composition of the materials (electrode vs ingots) and in the remelting slag during remelting, as well as the amount and composition of the NMIs prior to and after remelting, were investigated. Changes in the chemical composition can largely be explained by equilibrium reactions between the slag and the metal, thereby low Al contents in the remelted materials could only be achieved with the lowest Al2O3 contents in the slag. Furthermore, higher Al2O3 contents in the slag also lead to higher oxygen and sulfur contents in the steel as well as higher amounts of NMIs after remelting. The composition of the NMIs changed from alumina type for high Al2O3 contents to spinel type and other mixed MgO-SiO2 oxides for low Al2O3 contents. The results indicate solutions for the production of bearing steels with the lowest amounts of undesired large and hard NMIs.

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Tribological characterization of potential crankshaft bearing steels for roller bearing engines

Proceedings of the Institution of Mechanical Engineers Part J Journal of Engineering Tribology ◽

10.1177/1350650120957780 ◽

2020 ◽

pp. 135065012095778

Author(s):

Aleks Vrček ◽

Tobias Hultqvist ◽

Tomas Johannesson ◽

Pär Marklund ◽

Roland Larsson

Keyword(s):

Residual Stress ◽

Combustion Engine ◽

Roller Bearing ◽

Surface Hardness ◽

Bearing Steel ◽

Engine Oil ◽

Limiting Factor ◽

Surface Fatigue ◽

Bearing Steels ◽

Wear Damage

A crankshaft roller bearing internal combustion engine (ICE) offers a five percent or more improvement in overall engine efficiency and, thereby, a reduction in a five percent of CO2 emissions, compared to a plain bearing supported crankshaft. Current forged crankshaft steels represent the limiting factor of the rolling component, therefore, a replacement of the crankshaft steel is required. Apart from this, the tribology of the rolling contacts has been shown to be detrimental when lubricated with current engine oils. Therefore, this paper investigates the tribological performance of potential crankshaft bearing steels, i.e. DIN C56E2 (G55); DIN 50CrMo4 (G50); and DIN 100Cr6 (G3), while utilizing a state-of-the-art low viscosity 0W20 engine oil and under conditions prevalent to ICE. For this, damage mode investigation was performed in a disc-on-disc setup. Based on the results, wear damage of DIN 100Cr6 discs was shown to be dependent on the steel grade of which the counterpart disc was made from and surface hardness difference between both discs. In addition, surface fatigue and wear damage can be completely eliminated by selecting a proper surface roughness and hardness combination. Also, while under an elevated roughness level, engine oil was shown to promote both surface fatigue and wear damage through the work of ZDDP additives, which under extreme conditions can act as an extreme pressure (EP) additive. The residual stress measurements using the XRD technique revealed relatively high compressive residual stresses for G55 and G50 in comparison to G3 steel after surface induction hardening. In addition, no significant changes in residual stress for G55 and G50 were observed after the test. In contrast, relatively high tensile stress was observed for G3 near the surface region. This suggests that the most commonly used 100Cr6 bearing steel, in this case, is the most susceptible to surface fatigue.

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Quantitative Analysis of Inclusion Engineering on the Fatigue Property Improvement of Bearing Steel

Metals ◽

10.3390/met9040476 ◽

2019 ◽

Vol 9 (4) ◽

pp. 476 ◽

Cited By ~ 3

Author(s):

Chao Gu ◽

Min Wang ◽

Yanping Bao ◽

Fuming Wang ◽

Junhe Lian

Keyword(s):

Fatigue Life ◽

Quantitative Analysis ◽

Critical Size ◽

Fatigue Behavior ◽

Fatigue Cracks ◽

Fatigue Property ◽

Bearing Steel ◽

Fatigue Properties ◽

Bearing Steels ◽

Inclusion Distribution

The fatigue property is significantly affected by the inner inclusions in steel. Due to the inhomogeneity of inclusion distribution in the micro-scale, it is not straightforward to quantify the effect of inclusions on fatigue behavior. Various investigations have been performed to correlate the inclusion characteristics, such as inclusion fraction, size, and composition, with fatigue life. However, these studies are generally based on vast types of steels and even for a similar steel grade, the alloy concept and microstructure information can still be of non-negligible difference. For a quantitative analysis of the fatigue life improvement with respect to the inclusion engineering, a systematic and carefully designed study is still needed to explore the engineering dimensions of inclusions. Therefore, in this study, three types of bearing steels with inclusions of the same types, but different sizes and amounts, were produced with 50 kg hot state experiments. The following forging and heat treatment procedures were kept consistent to ensure that the only controlled variable is inclusion. The fatigue properties were compared and the inclusions that triggered the fatigue cracks were analyzed to deduce the critical sizes of inclusions in terms of fatigue failure. The results show that the critical sizes of different inclusion types vary in bearing steels. The critical size of the spinel is 8.5 μm and the critical size of the calcium aluminate is 13.5 μm under the fatigue stress of 1200 MPa. In addition, with the increase of the cleanliness of bearing steels, the improvement of fatigue properties will reach saturation. Under this condition, further increasing of the cleanliness of the bearing steel will not contribute to the improvement of fatigue property for the investigated alloy and process design.

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Corrosive Damage Close to Nonmetallic Inclusions in Bearing Steels

Steel in Translation ◽

10.3103/s0967091218030063 ◽

2018 ◽

Vol 48 (3) ◽

pp. 197-201

Author(s):

S. I. Gubenko ◽

A. B. Sychkov ◽

E. V. Parusov ◽

A. I. Denisenko ◽

A. N. Zavalishchin

Keyword(s):

Nonmetallic Inclusions ◽

Bearing Steels

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On the Fine Sand Marks With a Cloudy Appearance in Roller-Bearing Steel SUJ 3

Tetsu-to-Hagane ◽

10.2355/tetsutohagane1955.46.14_1751 ◽

1960 ◽

Vol 46 (14) ◽

pp. 1751-1757

Author(s):

Kiyoji Deguchi ◽

Yoshimichi Matsumoto

Keyword(s):

Roller Bearing ◽

Fine Sand ◽

Bearing Steel

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On the Nonmetallic Inclusions of a Bearing Steel Treated with Acidic Slag

Tetsu-to-Hagane ◽

10.2355/tetsutohagane1955.48.13_1659 ◽

1962 ◽

Vol 48 (13) ◽

pp. 1659-1666

Author(s):

Koshi KATO

Keyword(s):

Nonmetallic Inclusions ◽

Bearing Steel

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A METHOD FOR OPTIMIZING CHEMICAL COMPOSITION OF STEELS TO REDUCE RADICALLY THEIR ALLOY ELEMENTS AND INCREASE SERVICE LIFE OF MACHINE COMPONENTS

EUREKA Physics and Engineering ◽

10.21303/2461-4262.2017.00253 ◽

2017 ◽

Vol 1 ◽

pp. 3-12

Author(s):

Nikolai Kobasko

Keyword(s):

Chemical Composition ◽

Service Life ◽

Alloy Element ◽

Steel Grades ◽

Computer Calculations ◽

Increase Service Life ◽

Quenched Steel ◽

Chemical Composition Of Steel ◽

Compressive Residual Stresses ◽

Strength And Ductility

A method for optimizing chemical composition of steel is proposed and a correlation is established to reduce cardinally alloy elements in existing steel grades that results in high compressive residual stresses at the surface of intensively quenched steel parts and increasing strength and ductility of material due to super- strengthening phenomenon. The algorithm of optimization consists in reducing alloy elements in existing alloy steel in 1.5 – 2 times and then lowering step-by-step content of steel, beginning from the most costly alloy element and ending the most cheaper one, until established correlation is satisfied. The range of reduction is minimal and during computer calculations can be chosen as 0,001wt%. The proposed approach can save alloy elements, energy, increase service life of machine components and improve environmental condition. The method is a basis for development of the new low hardenability (LH) and optimal hardenability (OH) steels.

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Complex Precipitates of TiN-MCx in GCr15 Bearing Steel

10.20944/preprints201905.0289.v1 ◽

2019 ◽

Author(s):

Qianren Tian ◽

Guocheng Wang ◽

Xinghu Yuan ◽

Qi Wang ◽

Seetharaman Sridhar

Keyword(s):

Volume Fraction ◽

Early Stage ◽

Nucleation Site ◽

Bearing Steel ◽

Precipitation Behavior ◽

Heterogeneous Nucleation Site ◽

Bearing Steels ◽

Advancing Front ◽

Gcr15 Bearing Steel ◽

Second Phases

Nitride and carbide are the second phases which play an important role in the performance of bearing steel, and their precipitation behavior is complicated. In this study, TiN-MCx precipitations in GCr15 bearing steels were obtained by non-aqueous electrolysis, and their precipitation mechanisms were studied. TiN is the effective heterogeneous nucleation site for Fe7C3 and Fe3C, therefore, MCx can precipitate on the surface of TiN easily, its chemistry component consists of M3C and M7C3 (M = Fe, Cr, Mn) and Cr3C2. TiN-MCx with high TiN volume fraction, TiN forms in early stage of solidification, and MCx precipitates on TiN surface after TiN engulfed by the solidification advancing front. TiN-MCx with low TiN volume fraction, TiN and MCx form in late stage of solidification, TiN can not grow sufficiently and is covered by a large number of precipitated MCx particles.

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Research of the kinetics of thickness of the boundary layers of lubricating materials applied to drilling technology

Proceedings of OilGasScientificResearchProjects Institute SOCAR ◽

10.5510/ogp20210200502 ◽

2021 ◽

pp. 115-120

Author(s):

R.A. Ismakov ◽

◽

V.G. Konesev ◽

F.N. Yangirov ◽

G.L. Gaymaletdinova ◽

...

Keyword(s):

Service Life ◽

Boundary Layers ◽

Friction Pair ◽

Roller Bearing ◽

Equipment Safety ◽

Efficiency And Effectiveness ◽

Drilling Technology ◽

Resource Characteristics ◽

Friction Surfaces ◽

Kinetics Of

Improving the operational properties of lubricants increases the service life of the mechanisms and increase the durability of rubbing joints, which has a positive effect on the indicators of technical and economic efficiency and equipment safety. Therefore, great attention in tribology is paid to the analysis of the state of friction units in technology and the assessment of their resource characteristics, which makes it possible to increase their service life. The research aim is to study the general provisions on lubricants and lubricants, as well as the features of the boundary layers formation on friction surfaces and the observed patterns. Calculations of the boundary layers thickness using lubricating reagents at different energetic loading of the friction pair were carried out as applied to the roller bearing of a roller cone bit in the medium of cylinder oil 52 and DPS grease. The proposed research methodology made it possible to in-crease the efficiency and effectiveness of the means development for improving the tribotech-nical properties of drilling lubricants.

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