Influence of Additional Electrical Current on Machinability of BN Free-Machining Steel in Turning

Tanaka, Ryutaro; Lin, Yongchuan; Hosokawa, Akira; Ueda, Takashi; Yamada, Keiji

doi:10.1299/jamdsm.3.171

Cited by 14 publications

(6 citation statements)

References 4 publications

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“…In recent years, the possibility of adding BN to improve the machinability of steel was explored (Tanaka et al, 2007;Tanaka et al, 2009). The influences of steel composition and tool material on the machinability have been investigated and confirmed that BN inclusions could improve the machinability of steel significantly.…”

Section: Introductionmentioning

confidence: 95%

Basic research on mechanism of BN inclusion in improving the machinability of steel

Chen¹,

Bao²,

Wang³

et al. 2014

REVMETAL

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Boron nitride-added eco-friendly free cutting steel has recently drawn more and more attention. But, the mechanisms explaining the role of BN inclusions improving the machinability of steels is not very clear. In this investigation, the material removal mechanism for cutting of BN inclusions in steels is explored, using a combination of theoretical analysis and a series of experiments. First, the actual shape of BN inclusions is observed and the amount and distribution of BN inclusions is quantitatively analyzed. Subsequently, the cutting performance of the steel is determined by cutting experimental tests. Moreover, the micro mechanical properties and the material removal mechanisms for cutting of BN inclusions are investigated by means of nanoindentation. The results revealed that the BN inclusions are hexagonal and are uniformly distributed, their average content is 23.2 per unit area and their volume fraction is 0.51% in the steel with 74 ppm B and 180 ppm N. It is shown that BN inclusions can improve the cutting performance of steel significantly, and a model describing the material removal mechanism for cutting of BN inclusions is proposed. BN inclusions act as stress concentration source, lubrication and wrappage of hard particles. RESUMEN:Investigación básica sobre los mecanismos que explican el papel de las inclusiones de BN en la mejora de la maquinabilidad de aceros. Los aceros de fácil mecanizado o corte libre con nitruro de boro agregado han despertado un gran interés. Sin embargo, aún no se han determinado los mecanismos que explican el papel de las inclusiones de BN en la mejora de la maquinabilidad de estos aceros. En este trabajo, se investigan los mecanismos de corte de las inclusiones BN en aceros mediante la combinación de un análisis teórico y una serie de experimentos. En primer lugar, se determina la morfología de las inclusiones BN y se analiza cuantitativamente la cantidad y distribución de las mismas. Posteriormente, el rendimiento de corte del acero se determina mediante ensayos de corte. Por otra parte, las propiedades mecánicas locales y los mecanismos de eliminación de material para el corte de inclusiones BN son investigados por medio de nanoindentación. Los resultados revelaron que las inclusiones son BN con forma hexagonal y se distribuyen de manera uniforme, su contenido promedio es de 23,2 por unidad de superficie y su fracción de volumen es 0,51% en el acero con un contenido de 74 ppm de B y 180 ppm N. Se demuestra que las inclusiones BN pueden mejorar el rendimiento de corte del acero de manera significativa, y se presenta un modelo que describe el mecanismo de corte de las inclusiones de BN. Finalmente, se comprueba que los BN actúan como fuente de concentración de tensiones, la lubricante y de conglomerante de partículas duras.

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Section: Introductionmentioning

confidence: 95%

Basic research on mechanism of BN inclusion in improving the machinability of steel

Chen¹,

Bao²,

Wang³

et al. 2014

REVMETAL

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“…[8] are shown in Table IV. [23,24] Combined with the data in Table IV Equation [10] confirms that in the liquid region and the mushy region, DG>0.…”

Section: A Thermodynamic Condition Of Bn Precipitationmentioning

confidence: 99%

Characteristics of BN Precipitation and Growth During Solidification of BN Free-Machining Steel

Wang

Yang

Bao

2014

Metall Mater Trans B

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The effects of the cooling rate on the morphology and diameter distribution of BN inclusions and the solidification structure have been observed. The precipitation and growth behavior of BN inclusions during solidification have been analyzed with the help of thermodynamics and kinetics. The experimental results show that the diameter of BN inclusions increases with the decrease of cooling rate. The calculation results show that the segregation of boron is much stronger than that of nitrogen. Considering the segregation of solutes, BN formation takes place only in the mushy region when the solid fraction is close to 1 during solidification of BN freemachining steel. The difference between the nitrogen concentration in the remnant liquid phase increased by segregation and that in equilibrium is a driving force for BN growth. With the increase of cooling rate, the time for BN growth decreases and the radius of the precipitated BN inclusions is reduced.

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“…Boron nitride, also called 'white graphite', has a hexagonal lattice and behaves similar to graphite, i.e. acts as a lubricant in steel machining processes [11][12][13][14]. According to available literature, boron nitride inclusions do not affect anisotropy of mechanical properties, increase strength, have positive effect on machinability and cause no environmental problems.…”

Section: Introductionmentioning

confidence: 99%

Free-Cutting Cr–Ni–Mo Steel

Ryabov

Prokaeva

Amosova

2018

SSP

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The paper presents theoretical and practical study of formation of non-metallic inclusions in a medium-carbon free-cutting structural steel. FactSage software package was used for thermodynamic modelling of inclusion behaviour. Formation temperature and the amount of aluminium oxides, boron nitrides, manganese sulphides and aluminium nitrides were calculated. Inclusions in the steel form in the sequence Al2O3 > BN > MnS > AlN. The object of practical research was a cast billet of A38KhGMAR grade steel. It was melted in a laboratory induction furnace; boron and nitrogen were introduced after deoxidation of the melt with primary aluminium. Quality analysis included determination of chemical composition, macro-and microstructure, type and shape of non-metallic inclusions. Fine and uniformly distributed boron nitride inclusions were obtained throughout the metal matrix; their distribution was studied both qualitatively and quantitatively. Beside isolated particles, boron nitrides are also presented as a component of complex inclusions with manganese sulphides. Inclusion morphology is mostly spherical. The size of BN inclusions varies from 0.41 to 7.23 μm.

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Influence of Additional Electrical Current on Machinability of BN Free-Machining Steel in Turning

Cited by 14 publications

References 4 publications

Basic research on mechanism of BN inclusion in improving the machinability of steel

Basic research on mechanism of BN inclusion in improving the machinability of steel

Characteristics of BN Precipitation and Growth During Solidification of BN Free-Machining Steel

Free-Cutting Cr–Ni–Mo Steel

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