The Experts below are selected from a list of 258 Experts worldwide ranked by ideXlab platform
Seiichi Nishino - One of the best experts on this subject based on the ideXlab platform.
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subsurface crack initiation and propagation mechanism under the super long fatigue regime for high speed tool steel jis skh51 by fracture surface topographic analysis
Jsme International Journal Series A-solid Mechanics and Material Engineering, 2006Co-Authors: Kazuaki Shiozawa, Yuuichi Morii, Seiichi NishinoAbstract:In order to study the subsurface crack initiation and propagation mechanism of high strength steel under a very high cycle fatigue regime, computational simulation with fracture surface topographic analysis (FRASTA) was carried out for subsurface fatigue crack initiated specimens of high speed tool steel (JIS SKH51) obtained from the rotating bending fatigue test in air. A remarkable area formed around the Nonmetallic Inclusion inside the fish-eye region on the fracture surface, which is a feature on the fracture surface in super long fatigue. This so-called GBF (granular-bright-facet) was observed in detail by a scanning probe microscope and a three-dimensional SEM. The GBF area, in which a rich carbide distribution was detected by EPMA, revealed a very rough and granular morphology in comparison with the area inside the fish-eye. It was clearly simulated by FRASTA that multiple microcracks were initiated and dispersed by the decohesion of a spherical carbide from the matrix around a Nonmetallic Inclusion, and converged into the GBF area during the fatigue process. After the formation of the GBF area, interior cracks grew radially and a fish-eye pattern formed on the fracture surface.
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effect of stress ratio on subsurface fatigue fracture of high speed tool steel shk51
Transactions of the Japan Society of Mechanical Engineers. A, 2006Co-Authors: Kazuaki Shiozawa, Seiichi Nishino, Yasuyuki YachiAbstract:The effect of stress ratio (R=σmin/σmax) on subsurface fatigue fracture of high-speed tool steel, SKH51, was investigated using smooth specimen subjected to axial reversed loading in air at room temperature. From the experimental results, interior Inclusion induced fracture occurred in each stress ratio. The number of cycles to the transition from surface fracture mode to subsurface fracture mode depended on R. A granular-bright-facet (GBF) area formed around the Nonmetallic Inclusion inside the fish-eye zone on the fracture surface of the specimen in long-life fatigue regime, Nf>106, at R=-1.3, -1 and 0. From the detail observation of GBF area by three-dimensional SEM, the roughness of GBF area depended on the stress intensity factor range, Δkinc, s, at the Inclusion of facture origin.
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subsurface crack initiation and propagation mechanism in the super long fatigue regime for high speed tool steel jis skh51 by fracture surface topographic analysis
Transactions of the Japan Society of Mechanical Engineers. A, 2004Co-Authors: Kazuaki Shiozawa, Yuuichi Morii, Seiichi NishinoAbstract:In order to study the subsurface crack initiation and propagation mechanism of high strength steel in very high cycle fatigue regime, computational simulation with fracture surface topographic analysis (FRASTA) was carried out for subsurface fatigue crack initiated specimens of high speed tool steel, JIS SKH 51, obtained from the rotating bending fatigue test in air. A remarkable area formed around the Nonmetallic Inclusion inside the fish-eye region on the fracture surface, which is a feature on the fracture surface in super long fatigue and named as GBF (granular-bright-facet), was observed in detail by a scanning probe microscope and a three-dimensional SEM. The GBF area, in which a rich carbide distribution was detected by EPMA, revealed a very rough and granular morphology in comparison with the area inside the fish-eye. It was clearly simulated by FRASTA method that multiple microcracks initiated depressively by the decohesion of spherical carbide from the matrix around a Nonmetallic Inclusion and coalesce each other into the GBF area during fatigue process. After the formation of GBF area, interior crack grew radially and the fish-eye pattern formed on the fracture surface.
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a study of subsurface crack initiation and propagation mechanism of high strength steel by fracture surface topographic analysis
Journal of The Society of Materials Science Japan, 2003Co-Authors: Kazuaki Shiozawa, Yuuichi Morii, Seiichi Nishino, L U LiantaoAbstract:In order to study the mechanism of the subsurface crack initiation and propagation of high strength steel in very high-cycle region, computational simulation with fracture surface topographic analysis (FRASTA) method was carried out for specimens of high-carbon-chromium bearing steel, JIS SUJ2, obtained from the rotary-bending fatigue test in air. A remarkable area formed around the Nonmetallic Inclusion inside the fish-eye zone on the fracture surface, which is a feature on the fracture surface in superlong fatigue and named as GBF (granular-bright-facet), was observed in detail by a scanning probe microscope and a three-dimensional SEM. The GBF area, in which a rich carbide distribution was detected by EPMA, revealed a very rough and granular morphology in comparison with the area inside the fish eye. It was clearly simulated by the FRASTA method that multiple microcracks initiate dispersively by the decohesion of spherical carbide from the matrix around a Nonmetallic Inclusion and coalesce each other into the GBF area during fatigue process. After formation of the GBF area, interior crack grew radially and the fish-eye pattern formed on the fracture surface.
Kazuaki Shiozawa - One of the best experts on this subject based on the ideXlab platform.
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subsurface crack initiation and propagation mechanism under the super long fatigue regime for high speed tool steel jis skh51 by fracture surface topographic analysis
Jsme International Journal Series A-solid Mechanics and Material Engineering, 2006Co-Authors: Kazuaki Shiozawa, Yuuichi Morii, Seiichi NishinoAbstract:In order to study the subsurface crack initiation and propagation mechanism of high strength steel under a very high cycle fatigue regime, computational simulation with fracture surface topographic analysis (FRASTA) was carried out for subsurface fatigue crack initiated specimens of high speed tool steel (JIS SKH51) obtained from the rotating bending fatigue test in air. A remarkable area formed around the Nonmetallic Inclusion inside the fish-eye region on the fracture surface, which is a feature on the fracture surface in super long fatigue. This so-called GBF (granular-bright-facet) was observed in detail by a scanning probe microscope and a three-dimensional SEM. The GBF area, in which a rich carbide distribution was detected by EPMA, revealed a very rough and granular morphology in comparison with the area inside the fish-eye. It was clearly simulated by FRASTA that multiple microcracks were initiated and dispersed by the decohesion of a spherical carbide from the matrix around a Nonmetallic Inclusion, and converged into the GBF area during the fatigue process. After the formation of the GBF area, interior cracks grew radially and a fish-eye pattern formed on the fracture surface.
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effect of stress ratio on subsurface fatigue fracture of high speed tool steel shk51
Transactions of the Japan Society of Mechanical Engineers. A, 2006Co-Authors: Kazuaki Shiozawa, Seiichi Nishino, Yasuyuki YachiAbstract:The effect of stress ratio (R=σmin/σmax) on subsurface fatigue fracture of high-speed tool steel, SKH51, was investigated using smooth specimen subjected to axial reversed loading in air at room temperature. From the experimental results, interior Inclusion induced fracture occurred in each stress ratio. The number of cycles to the transition from surface fracture mode to subsurface fracture mode depended on R. A granular-bright-facet (GBF) area formed around the Nonmetallic Inclusion inside the fish-eye zone on the fracture surface of the specimen in long-life fatigue regime, Nf>106, at R=-1.3, -1 and 0. From the detail observation of GBF area by three-dimensional SEM, the roughness of GBF area depended on the stress intensity factor range, Δkinc, s, at the Inclusion of facture origin.
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subsurface crack initiation and propagation mechanism in the super long fatigue regime for high speed tool steel jis skh51 by fracture surface topographic analysis
Transactions of the Japan Society of Mechanical Engineers. A, 2004Co-Authors: Kazuaki Shiozawa, Yuuichi Morii, Seiichi NishinoAbstract:In order to study the subsurface crack initiation and propagation mechanism of high strength steel in very high cycle fatigue regime, computational simulation with fracture surface topographic analysis (FRASTA) was carried out for subsurface fatigue crack initiated specimens of high speed tool steel, JIS SKH 51, obtained from the rotating bending fatigue test in air. A remarkable area formed around the Nonmetallic Inclusion inside the fish-eye region on the fracture surface, which is a feature on the fracture surface in super long fatigue and named as GBF (granular-bright-facet), was observed in detail by a scanning probe microscope and a three-dimensional SEM. The GBF area, in which a rich carbide distribution was detected by EPMA, revealed a very rough and granular morphology in comparison with the area inside the fish-eye. It was clearly simulated by FRASTA method that multiple microcracks initiated depressively by the decohesion of spherical carbide from the matrix around a Nonmetallic Inclusion and coalesce each other into the GBF area during fatigue process. After the formation of GBF area, interior crack grew radially and the fish-eye pattern formed on the fracture surface.
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a study of subsurface crack initiation and propagation mechanism of high strength steel by fracture surface topographic analysis
Journal of The Society of Materials Science Japan, 2003Co-Authors: Kazuaki Shiozawa, Yuuichi Morii, Seiichi Nishino, L U LiantaoAbstract:In order to study the mechanism of the subsurface crack initiation and propagation of high strength steel in very high-cycle region, computational simulation with fracture surface topographic analysis (FRASTA) method was carried out for specimens of high-carbon-chromium bearing steel, JIS SUJ2, obtained from the rotary-bending fatigue test in air. A remarkable area formed around the Nonmetallic Inclusion inside the fish-eye zone on the fracture surface, which is a feature on the fracture surface in superlong fatigue and named as GBF (granular-bright-facet), was observed in detail by a scanning probe microscope and a three-dimensional SEM. The GBF area, in which a rich carbide distribution was detected by EPMA, revealed a very rough and granular morphology in comparison with the area inside the fish eye. It was clearly simulated by the FRASTA method that multiple microcracks initiate dispersively by the decohesion of spherical carbide from the matrix around a Nonmetallic Inclusion and coalesce each other into the GBF area during fatigue process. After formation of the GBF area, interior crack grew radially and the fish-eye pattern formed on the fracture surface.
Yuuichi Morii - One of the best experts on this subject based on the ideXlab platform.
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subsurface crack initiation and propagation mechanism under the super long fatigue regime for high speed tool steel jis skh51 by fracture surface topographic analysis
Jsme International Journal Series A-solid Mechanics and Material Engineering, 2006Co-Authors: Kazuaki Shiozawa, Yuuichi Morii, Seiichi NishinoAbstract:In order to study the subsurface crack initiation and propagation mechanism of high strength steel under a very high cycle fatigue regime, computational simulation with fracture surface topographic analysis (FRASTA) was carried out for subsurface fatigue crack initiated specimens of high speed tool steel (JIS SKH51) obtained from the rotating bending fatigue test in air. A remarkable area formed around the Nonmetallic Inclusion inside the fish-eye region on the fracture surface, which is a feature on the fracture surface in super long fatigue. This so-called GBF (granular-bright-facet) was observed in detail by a scanning probe microscope and a three-dimensional SEM. The GBF area, in which a rich carbide distribution was detected by EPMA, revealed a very rough and granular morphology in comparison with the area inside the fish-eye. It was clearly simulated by FRASTA that multiple microcracks were initiated and dispersed by the decohesion of a spherical carbide from the matrix around a Nonmetallic Inclusion, and converged into the GBF area during the fatigue process. After the formation of the GBF area, interior cracks grew radially and a fish-eye pattern formed on the fracture surface.
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subsurface crack initiation and propagation mechanism in the super long fatigue regime for high speed tool steel jis skh51 by fracture surface topographic analysis
Transactions of the Japan Society of Mechanical Engineers. A, 2004Co-Authors: Kazuaki Shiozawa, Yuuichi Morii, Seiichi NishinoAbstract:In order to study the subsurface crack initiation and propagation mechanism of high strength steel in very high cycle fatigue regime, computational simulation with fracture surface topographic analysis (FRASTA) was carried out for subsurface fatigue crack initiated specimens of high speed tool steel, JIS SKH 51, obtained from the rotating bending fatigue test in air. A remarkable area formed around the Nonmetallic Inclusion inside the fish-eye region on the fracture surface, which is a feature on the fracture surface in super long fatigue and named as GBF (granular-bright-facet), was observed in detail by a scanning probe microscope and a three-dimensional SEM. The GBF area, in which a rich carbide distribution was detected by EPMA, revealed a very rough and granular morphology in comparison with the area inside the fish-eye. It was clearly simulated by FRASTA method that multiple microcracks initiated depressively by the decohesion of spherical carbide from the matrix around a Nonmetallic Inclusion and coalesce each other into the GBF area during fatigue process. After the formation of GBF area, interior crack grew radially and the fish-eye pattern formed on the fracture surface.
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a study of subsurface crack initiation and propagation mechanism of high strength steel by fracture surface topographic analysis
Journal of The Society of Materials Science Japan, 2003Co-Authors: Kazuaki Shiozawa, Yuuichi Morii, Seiichi Nishino, L U LiantaoAbstract:In order to study the mechanism of the subsurface crack initiation and propagation of high strength steel in very high-cycle region, computational simulation with fracture surface topographic analysis (FRASTA) method was carried out for specimens of high-carbon-chromium bearing steel, JIS SUJ2, obtained from the rotary-bending fatigue test in air. A remarkable area formed around the Nonmetallic Inclusion inside the fish-eye zone on the fracture surface, which is a feature on the fracture surface in superlong fatigue and named as GBF (granular-bright-facet), was observed in detail by a scanning probe microscope and a three-dimensional SEM. The GBF area, in which a rich carbide distribution was detected by EPMA, revealed a very rough and granular morphology in comparison with the area inside the fish eye. It was clearly simulated by the FRASTA method that multiple microcracks initiate dispersively by the decohesion of spherical carbide from the matrix around a Nonmetallic Inclusion and coalesce each other into the GBF area during fatigue process. After formation of the GBF area, interior crack grew radially and the fish-eye pattern formed on the fracture surface.
S. I. Gubenko - One of the best experts on this subject based on the ideXlab platform.
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Effect of “Nonmetallic Inclusion–matrix” phase boundaries on the cohesive resistance of steel
Metal Science and Heat Treatment, 2006Co-Authors: S. I. GubenkoAbstract:Changes in “Inclusion–matrix” phase boundaries in steel undergoing plastic deformation, which are connected with the susceptibility of Nonmetallic Inclusions to formation of voids, are studied. Different methods of steel treatment affecting the structure of “Inclusion–matrix” interphases are suggested.
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effect of Nonmetallic Inclusion matrix phase boundaries on the cohesive resistance of steel
Metal Science and Heat Treatment, 2006Co-Authors: S. I. GubenkoAbstract:Changes in “Inclusion–matrix” phase boundaries in steel undergoing plastic deformation, which are connected with the susceptibility of Nonmetallic Inclusions to formation of voids, are studied. Different methods of steel treatment affecting the structure of “Inclusion–matrix” interphases are suggested.
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sliding at Nonmetallic Inclusion matrix boundaries its effects on the distribution of local strain microinhomogeneities in armco iron and steels
Physics of Metals and Metallography, 1996Co-Authors: S. I. GubenkoAbstract:A study is reported into how the sliding brought on at Inclusion-matrix interphase boundaries by high-temperature deformation affects the evolution of strain microinhomogeneities in the matrix in contact with Nonmetallic Inclusions. It is shown that sliding brings on spikes in strain near nondeformable and plastic Inclusions.
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Splitting of Nonmetallic-Inclusion/steel-matrix interphase boundaries
Metal Science and Heat Treatment, 1994Co-Authors: S. I. GubenkoAbstract:In the last 15–20 years significant success has been achieved in studying the structure and behavior of grain boundaries, and this has led to the appearance of concepts such as grain-boundary dislocations, grainboundary crystal geometry models, and grain-boundary splitting, sliding and migration. The Inclusion/matrix boundaries have been studied very little, although the problem of these boundaries is even more complex than the grain boundary problem. The configuration of the Inclusion/matrix interphase boundaries in steel and the possible changes of their initial structure in the process of mechanical and thermal treatment are amenable to description in boundary structure defect terms.
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splitting of Nonmetallic Inclusion steel matrix interphase boundaries
Metal Science and Heat Treatment, 1994Co-Authors: S. I. GubenkoAbstract:In the last 15–20 years significant success has been achieved in studying the structure and behavior of grain boundaries, and this has led to the appearance of concepts such as grain-boundary dislocations, grainboundary crystal geometry models, and grain-boundary splitting, sliding and migration. The Inclusion/matrix boundaries have been studied very little, although the problem of these boundaries is even more complex than the grain boundary problem. The configuration of the Inclusion/matrix interphase boundaries in steel and the possible changes of their initial structure in the process of mechanical and thermal treatment are amenable to description in boundary structure defect terms.
Yukitaka Murakami - One of the best experts on this subject based on the ideXlab platform.
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Hydrogen embrittlement of high strength steels: Determination of the threshold stress intensity for small cracks nucleating at Nonmetallic Inclusions
Engineering Fracture Mechanics, 2013Co-Authors: Yukitaka Murakami, Toshihiko Kanezaki, Petros Athanasios SofronisAbstract:Abstract The objective of this study is to determine the threshold stress intensity factor for small cracks in high strength steels in a hydrogen environment by studying the failure of hydrogen pre-charged cylindrical specimens loaded in uniaxial tension. Fracture of these specimens under tension usually initiates at the largest Nonmetallic Inclusion contained in the specimen and such typical Inclusions are Al 2 O 3 ·(CaO) X and TiN. The onset of the failure process is the crack initiation and propagation from a cavity forming either through debonding along the Inclusion/matrix interface or through cracking of the Inclusion. By analyzing the stress intensity factor for planar cracks emanating from Inclusions, we calculated the threshold stress intensity by using experimental measurements of the applied tensile stress at the failure of the specimen. The results indicate that the threshold stress intensity is a linear function of the size of the Inclusion and the hydrogen concentration in the specimen upon failure. The size of the Inclusion is calculated as area , where area denote the area of the domain defined by projecting the Inclusion surface on a plane normal to the cylindrical axis of the specimen. Analysis of the experimental data indicates that the threshold stress intensity decreases as the Inclusion size decreases. The estimates of K TH obtained by this method through fracturing uniaxial tension specimens can be used as a lower bound of the resistance to hydrogen embrittlement (HE) of component of high strength steel containing small defects and cracks.
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a new Nonmetallic Inclusion rating method by positive use of hydrogen embrittlement phenomenon
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2013Co-Authors: Shinji Fujita, Yukitaka MurakamiAbstract:A new Inclusions rating method using hydrogen embrittlement of a tensile test specimen is proposed. This method is essentially based on the statistics of extremes for Inclusion rating where the maximum Inclusion size is determined by simple tensile testing of a hydrogen-precharged (H-precharged) specimen. Tensile tests were conducted using two bearing steels (SAE52100 HV 346, HV 447, HV 559, HV 611, HV 678 and ASTM-A485-1 HV 706, HV 715) and one spring steel (SAE5160, HV 651). Fatigue tests were conducted using SAE52100 bearing steel (HV 682). All H-precharged tensile specimens (SAE52100, ASTM-A485-1 and SAE5160) were fractured from internal Inclusions except the SAE52100 tensile specimens with a Vickers hardness of HV 346. It was confirmed that the distribution of extreme values of Inclusion sizes obtained by SAE52100 tensile testing with H-precharged specimens coincided with those obtained by SAE52100 fatigue testing. From these results, it is presumed that the Inclusion rating method by fatigue testing can be replaced by simple tensile testing with H-precharged specimens. The proposed method is more convenient and reliable than other existing Inclusion rating methods, i.e., fatigue testing and optical microscopy. The proposed method can be applied to specimens with a Vickers hardness of higher than HV 447.
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p75 elimination of conventional fatigue limit due to fatigue crack originated at Nonmetallic Inclusion and non propagation of fatigue crack originated at artificial small hole
Transactions of the Japan Society of Mechanical Engineers. A, 2005Co-Authors: Yukitaka Murakami, Junji NagataAbstract:The mechanism of fatigue failure in the ultra-high cycle regime was studied using a martensitic stainless steel. The effect of internal hydrogen trapped by Nonmetallic Inclusions on high cycle fatigue behaviour has been discussed by Murakami et al. In order to investigate more in detail the mechanism of the elimination of the conventional fatigue limit and the influence of hydrogen trapped by Inclusion, specimens with various artificial small defects were prepared. The fatigue failure of a specimen which contained an artificial hole occurred at Nf ≅108 from a Nonmetallic Inclusion which is smaller in size than the artificial small surface hole. In the case of the specimen containing two artificial holes connected with a fatigue crack, non-propagation crack was observed at the edge of the artificial hole, and the fatigue limit was in good agreement with the value predicted by the √area parameter model. In the case of the specimen whose fatigue crack originating at an Inclusion, the crack continued propagation, and finally the specimen failed. Considering that Nonmetallic Inclusions trap hydrogen, it is presumed that the elimination of the conventional fatigue limit due to fatigue crack originated at Nonmetallic Inclusion is caused by synergetic effect of cyclic stress and hydrogen trapped by Inclusions.
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Effects of Nonmetallic Inclusions on Fatigue Strength
Metal Fatigue, 2002Co-Authors: Yukitaka MurakamiAbstract:This chapter investigates the effects of Nonmetallic Inclusions on fatigue strength. For particular steel containing Inclusions, the ratio of fatigue strength to ultimate tensile strength could be decreased from 0.5 to 0.3 by a heat treatment that increases the ultimate tensile strength from 85 tonf / in 2 to 125 tonf / in 2 . As hardness is increased by heat treatment, the linear relationship between fatigue strength and the Vickers hardness is lost, and the fatigue strength then shows a large amount of scatter. The same Inclusion can have different effects on fatigue strength depending on the direction of loading. These results indicate that the shape and size of an Inclusion are the important factors. The fact that a Nonmetallic Inclusion exists at a fracture origin implies that, after a fatigue crack is nucleated at the interface between the Inclusion and the matrix, or the Inclusion itself is cracked, the crack extends into the microstructure, resulting in final fracture. When a crack is nucleated at the interface between an Inclusion and the matrix, or a crack originates through cracking of the Inclusion, stresses within the Inclusion are relieved, and the Inclusion domain may be regarded as mechanically equivalent to a stress-free defect or pore.
