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T. Lipiński

Abstract

The article discusses the effect of distance between submicroscopic oxide impurities (up to 2 μm in size) on the fatigue resistance coefficient 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. Furthermore 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 from austenitizing by 30 minutes in temperature 880°C 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 mathematically. The fatigue resistance coefficient of structural steel with the effect of spacing between submicroscopic oxide impurities was determined during rotary bending. The results revealed that fatigue resistance coefficient k is determined by the distance between submicroscopic non-metallic inclusions and tempering temperature.

Open access

Tomasz Lipiński

Abstract

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 7 heats produced in an industrial plant. Fourteen heats were produced in a 100 ton oxygen converter. All heats 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 heat treatments were selected to produce heats with different microstructure of steel, from hard microstructure of tempered martensite, through sorbitol to the ductile microstructure of spheroidite. 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.

Open access

Shiqiang Qin, Yi Tan, Jiayan Li, Dachuan Jiang, Shutao Wen and Shuang Shi

boron diffusion because impurities tend to pile up toward defects. Fig. 3 SEM images of silicon wafer surface: (a) surface of the silicon wafer before EBI; (b, d) and (c, e) surfaces of the silicon wafer after EBI for 1 h. The boron profile in silicon wafer without oxide layer after EBI for 1 h is illustrated in Fig. 4 . The surface boron concentration after EBI is extremely high, and boron concentration inside the silicon is lower than in the original wafer without EBI. This phenomenon indicates that EBI can induce boron impurities in silicon. EBI

Open access

Masroor Ahmad Bhat, R. A. Zargar, Anchit Modi, M. Arora and N. K. Gaur

1 Introduction The physical properties of mixed valence transition metal oxides can be tuned by interplay among charge, spin and orbital degrees of freedom interacting with crystal lattice [ 1 , 2 ]. The geometrically frustrated hexagonal 114 phase in YBaCo 4 O 7 compound contains CoO 4 tetrahedron present in alternating layers of Kagomé arranged in triangular arrays [ 3 , 4 ]. Ba and O atoms form a close-packed structure with 4H (abac) stacking [ 3 , 5 ]. Y and Co atoms occupy the octahedral and tetrahedral sites in the lattice, respectively. The CoO4

Open access

Tanja Rozman Peterka, Tina Trdan Lušin, Jure Bergles, Zoran Ham, Rok Grahek and Uroš Urleb

. Prod. 73 (2010) 776–779; https://doi.org/10.1021/Np9007975 11. P. Ferraboschi, D. Colombo, M. De Mieri and P. Grisenti, Evaluation, synthesis and characterization of tacrolimus impurities, J. Antibiot. 65 (2012) 349–354; https://doi.org/10.1038/Ja.2012.28 12. C. D. Sommers, E. S. Pang, H. Ghasriani, R. T. Berendt, V. L. Vilker, D. A. Keire and M. T. Boyne, 2nd, Analyses of marketplace tacrolimus drug product quality: bioactivity, NMR and LC-MS, J. Pharm. Biomed. Anal. 85 (2013) 108–117; https://doi.org/10.1016/j.jpba.2013.07.001 13. T

Open access

Jūlija Karasa and Ksenija Ivanova

Abstract

Raw clays from the Baltic region are characterized as smectite containing clays with significant amount of naturally occurring impurities that limiting the potential applications of crude Baltic clay resources. Purification of clay samples from Šaltiškių deposit (Venta basin) was carried out by varied concentration hydrochloric acid solutions and resulted in fine removal of carbonates and iron oxide. The main idea of this work is to widen the possible applications of local clay resources providing a new type of raw material for further organoclay production.

Open access

T. Lipiński, A. Wach and E. Detyna

Abstract

The article discusses the effect of large oxide impurities (a diameter larger than 10 μm in size) on the fatigue resistance of structural steel of high purity during rotary bending. The study was performed on 7 heats produced in an industrial plant. The heats were produced in 140 ton electric furnaces. All heats were desulfurized.

The experimental material consisted of semi-finished products of high-grade, carbon structural steel with: manganese, chromium, nickel, molybdenum and boron. Steel sections with a diameter of 18 mm were hardened from austenitizing by 30 minutes in temperature 880°C and tempered at a temperature of 200, 300, 400, 500 and 600°C for 120 minutes and air-cooled. The experimental variants were compared in view of the heat treatment options. Fatigue tests were performed with the use of a rotary bending machine at a frequency of 6000 cpm. The results were statistical processed and presented in graphic form.

This paper discusses the results of the relative volume of large impurities, the fatigue strength for various heat processing options.

Open access

R. Shvab, E. Hryha, A. M. Tahir and L. Nyborg

Abstract

The state of the powder surface represents one of the main interests in the whole cycle of components’ production using powder metallurgy (PM) route. Large specific surface area of the powder in combination with often alloying with oxygen sensitive elements results in oxidation of the powder surface in most of the cases. The information about surface chemistry of the powder is of vital importance for further consolidation and sintering steps. Surface sensitive analytical techniques – X-ray photoelectron spectroscopy (XPS) and high-resolution scanning electron microscopy combined with energy dispersive X-ray analysis (HR SEM+EDX) were used for surface chemical analysis of the 60Cu-40Sn bronze powder. Determination of the compositional profiles and estimation of the surface oxide layer thickness was done by altering of ion etching and XPS analysis. The results showed tin oxide enrichment and presence of copper hydroxide on the surface of the powder particles. The impurities of P, Zn and Ca were also detected on the top surface of the powder in trace amounts.

Open access

S.Y. Chang, Y.W. Cheon, Y.H. Yoon, Y.H. Kim, J.Y. Kim, Y.K. Lee and W.H. Lee

Abstract

Characteristics of electro-discharge-sintering of the Ti-37.5at.% Si powder mixture was investigated as a function of the input energy, capacitance, and discharge time without applying any external pressure. A solid bulk of Ti5Si3 was obtained only after in less than 129 μsec by the EDS process. During a discharge, the heat is generated to liquefy and alloy the particles, and which enhances the pinch pressure can condensate them without allowing a formation of pores. Three step processes for the self-consolidation mechanism during EDS are proposed; (a) a physical breakdown of oxide film on elemental as-received powder particles, (b) alloying and densifying the consolidation of powder particles by the pinch pressure, and (c) diffusion of impurities into the consolidated surface.

Open access

F. Binczyk, J. Cwajna and P. Gradoń

Abstract

Paper presents the results of ATD and DSC analysis of two superalloys used in casting of aircraft engine parts. The main aim of the research was to obtain the solidification parameters, especially Tsol and Tliq, knowledge of which is important for proper selection of casting and heat treatment parameters. Assessment of the metallurgical quality (presence of impurities) of the feed ingots is also a very important step in production of castings. It was found that some of the feed ingots delivered by the superalloy producers are contaminated by oxides located in shrinkage defects. The ATD analysis allows for quite precise interpretation of first stages of solidification at which solid phases with low values of latent heat of solidification are formed from the liquid. Using DSC analysis it is possible to measure precisely the heat values accompanying the phase changes during cooling and heating which, with knowledge of phase composition, permits to calculate the enthalpy of formation of specific phases like γ or γ′.