Development in sheet steels has progressed in strong relation with automotive industry in Japan. To meet the requirements from automotive industry, various types of sheet steels including high and ...ultra high strength steel sheets have been developed. Progresses in three types of steel series will be discussed by checking the historical facts and technologies and their contributions. Introductions of interstitial free (IF) steel and continuous annealing system are the important events in mild steel developments for panels. Extensive work on finding the optimum mixtures of hard and soft phases to improve elongation of steels contributed to improve the crashworthiness of autobodies. Continuous annealing system also played an important role in producing these advanced high strength steels. Precipitation is used in a particular way which is to scavenge solute carbon and nitrogen and to prevent coarse cementite particle precipitation. It is also worth to point out that the collaborative activities particularly strong in Japan between steel manufacturers and auto companies have affected the progress in advanced sheet steels.
The tri-axial testing of rocks under compression is a widely popular measure for the assessment of strength of geological materials in the laboratory. In this regard, mechanical complexities of true ...tri-axial testing machines impel researchers to opt for simpler conventional tri-axial testing machines. To account for influential factors that affect quality of experimental data, observations derived from laboratory experiments that enable overcoming some drawbacks are presented herein. In the present study, a series of tri-axial tests on Kimachi sandstone under Conventional Tri-axial Compression (CTC), Conventional Tri-axial Extension (CTE), Reduced Tri-axial Compression (RTC), and Reduced Tri-axial Extension (RTE) conditions were carried out. The results suggested higher compressive strengths for the rock under tri-axial extension tests than the compression tests. This observation proves that the effect of intermediate confining pressure on material behavior is important and if feasible, should not be sacrificed for more economical alternatives. Generally, the loading and unloading experiments for a specific test type rendered the same results and the conventional and reduced paths in both the compression and extension tests did not affect the failure strength of the specimens. The effect of pre-existing cracks orientation with respect to the principal loading directions on crack growth was focused upon and related conclusions were subsequently drawn.
•The effect of intermediate principal stress in tri-axial loading on the failure strength of rock specimens was investigated.•The conventional and reduced tri-axial strengths, corresponding to faulting mechanisms in earthquakes, were scrutinized.•The crack tendency for propagation or opening, as a contributing factor to rock failure strength, was studied numerically.•The need for a more comprehensive failure criterion was emphasized via a short discussion on crack tensor theory.
The microstructures of intra-granular bainite nucleated on Ti-oxide particles (IGB) and grain boundary upper bainite (GBB) in Ti-deoxidized steel (Fe-0.1mass%C-1.5mass%Mn-2mass%Ni-1mass%Cu) were ...investigated by EBSD analysis and 3-dimentional observation. The steel was austenitized at 1673 K for 23 s, held at 803 K for 7 s-20 ks and then quenched to room temperature. 803 K is just below the bainite transformation start temperature. IGB and GBB were observed at 5% bainite transformation. Despite the formation of IGB, part of GBB grew to a size of 100 µm at 17% bainite transformation, and coarsened to 130–200 µm at 85% bainite transformation. Mechanism of the GBB coarsening is discussed in terms of differences in (1) the microstructures and (2) the nucleation site of IGB and GBB. A single packet with many blocks was observed in GBB nucleated at whole surface of austenite grain boundaries with a size of 400–500 µm, while multiple packets with two blocks were observed in IGB nucleated on Ti-oxide particles with a size of 1–2 µm. IGB suppressed the growth of GBB by impingement. However, as the GBB was much larger than IGB, part of the GBB was not impinged by the IGB and continued to grow. GBB grew until all blocks of GBB were impinged by IGB and/or transformation was finished, resulted in GBB coarsening.
Abetalipoproteinemia (ABL) is a rare autosomal recessive disorder caused by biallelic pathogenic mutations in the MTTP gene. Deficiency of microsomal triglyceride transfer protein (MTTP) abrogates ...the assembly of apolipoprotein (apo) B-containing lipoprotein in the intestine and liver, resulting in malabsorption of fat and fat-soluble vitamins and severe hypolipidemia. Patients with ABL typically manifest steatorrhea, vomiting, and failure to thrive in infancy. The deficiency of fat-soluble vitamins progressively develops into a variety of symptoms later in life, including hematological (acanthocytosis, anemia, bleeding tendency, etc.), neuromuscular (spinocerebellar ataxia, peripheral neuropathy, myopathy, etc.), and ophthalmological symptoms (e.g., retinitis pigmentosa). If left untreated, the disease can be debilitating and even lethal by the third decade of life due to the development of severe complications, such as blindness, neuromyopathy, and respiratory failure. High dose vitamin supplementation is the mainstay for treatment and may prevent, delay, or alleviate the complications and improve the prognosis, enabling some patients to live to the eighth decade of life. However, it cannot fully prevent or restore impaired function. Novel therapeutic modalities that improve quality of life and prognosis are awaited. The aim of this review is to 1) summarize the pathogenesis, clinical signs and symptoms, diagnosis, and management of ABL, and 2) propose diagnostic criteria that define eligibility to receive financial support from the Japanese government for patients with ABL as a rare and intractable disease. In addition, our diagnostic criteria and the entry criterion of low-density lipoprotein cholesterol (LDL-C) ＜15 mg/dL and apoB ＜15 mg/dL can be useful in universal or opportunistic screening for the disease. Registry research on ABL is currently ongoing to better understand the disease burden and unmet needs of this life-threatening disease with few therapeutic options.
The bainitic transformation kinetics and carbon enrichment of austenite during isothermal holding at 723–923 K were investigated for an Fe-0.1mass%C-0.5mass%Si-2.0mass%Mn alloy. The transformation ...progressed rapidly until approximately 50 s, after which transformation stasis was observed at 823 K. The carbon concentration of austenite increased as the transformation proceeded, and showed an almost constant value during stasis. It reached approximately 0.45–0.50% at 823 K, which corresponds to the carbon concentration at the T0’ composition with an additional strain energy of 100 J/mol associated with the transformation. After stasis, a slight increase in the ferrite or bainitic ferrite fraction was observed. The carbon concentration of austenite also increased and reached approximately 0.60%, clearly exceeding the carbon concentration at the T0 composition. These results imply that at the first stage, the bainite transformation occurs and shows the incomplete transformation, following which at the second stage, diffusional ferrite transformation proceeds. The additional strain energy associated with the transformation calculated from the carbon concentration at stasis due to the incomplete bainite transformation tends to decrease as the holding temperature increases. This indicates that strain relaxation due to the transformation occurred at higher holding temperatures.
The true triaxial test, which can simulate in-situ stress fields of nature which have different scalar quantity along three principal axes of stress, is the most effective experimental method for ...obtaining the mechanical and permeability property of rocks under overburden and tectonic stresses. The intermediate principal stress (σ2) is a control on the fracture strength, mechanical behavior and crack distribution of the deformed rocks. Thus, understanding the effect of the stress on the development of permeability anisotropy is crucial. To evaluate the influence of the σ2 on the permeability anisotropy, the permeability measurement lines in the σ1 and σ2 directions were added into an upgraded Mogi-type true triaxial test apparatus. We measured the permeability of Berea sandstone and Amatsu mudstone in the σ1 and σ2 direction under the conditions of true triaxial compression (σ3 < σ2 < σ1) with a constant σ3. In the Berea sandstone, we found that the permeability reduced with increasing mean stress and the magnitude of permeability anisotropy correlated with the intermediate principal stress. Photomicrographs and X-ray computed tomography observations for post-failure Berea sandstones revealed a phenomenon related to permeability: under high σ2 conditions, the fault gouge generated along final fractures causes permeability reduction of σ1 direction. For the Amatsu mudstone is too soft to be subject to brittle deformation. Thus, the development of the permeability anisotropy with increasing mean stresses was more pronounced in the Berea sandstone than the Amatsu mudstone.
Quenched martensitic steels are known to show the characteristic feature of stress–strain relations, with extremely low elastic limits and very large work-hardening. The continuum composite approach ...is one way to express this characteristic feature of stress–strain curves. Although the overall stress–strain curves, as a function of alloy chemistries of steels, were well represented by this approach, the relationship between the macroscopic deformation behaviors and microstructural information is yet to be clarified. A high-spatial-resolution digital image correlation analysis was conducted to demonstrate the possible unit size corresponding to the microstructure. The continuum composite approach model was also modified to consider the size effect of the microstructure on the stress–strain curves of the as-quenched martensitic steels. Strain concentrations were observed at various boundaries, including lath boundaries, and the characteristic microstructural size was also predicted by the present model, which is smaller than the reported spacing between adjacent strain-concentrated regions.
A modified continuum composite model was utilized to analyze the stress–strain behavior of as-quenched steels with a fully martensitic microstructure. The model was employed to express the ...stress–strain curves obtained by a simple tensile test and those obtained by forward and backward loading using a simple shear test machine. The study confirmed that the model can represent the stress–strain behavior under both forward and backward deformation. In addition, the evolution of local strain distributions during plastic deformation was investigated using a digital image correlation method. The strain distributions and their evolution during deformation were qualitatively represented using this model. The discrepancies between the model calculations and experiments are due to the limitations of the iso-work assumption and the impact of slip deformation on the macroscopic work-hardening behavior of martensitic steels. Highly strain-concentrated regions aligned along the longitudinal direction of the lath and block, known as in-lath-plane slips, may not play an important role in the work-hardening behavior of as-quenched martensitic steels. However, the other slips, namely the out-of-lath slip, may play a significant role in the work hardening of as-quenched martensitic steels.
The distribution of alloying elements was investigated to clarify latent features of the microstructure formation in TRIP-aided Multi-phase steels by using an unsupervised machine learning technique. ...The cold-rolled specimens with a composition of Fe-0.20mass%C-1.5mass%Si-1.5mass%Mn were heat-treated under various conditions. The FE-EPMA (field emission electron probe microanalysis) method was used to accurately measure the distribution of C, Si and Mn. The two-phase microstructure of ferrite and austenite was formed during intercritical annealing at 800 °C for 120 s. C and Mn were distributed in the austenite region while Si was distributed in the ferrite region. Part of the austenite transformed to bainite by subsequent heat-treatment of isothermal holding at 400 °C for 1200 s. The C concentration in the austenite region increased due to bainite formation. The microstructure formation factor was estimated by primary component analysis of big data on the elemental distribution. The cumulative contribution ratio of the second principal component was 0.85. Therefore, most of the information was contained in the first and second principal components. In the first principal component, the coefficients for the standardized C and Mn concentrations possessed positive values, while that for the standardized Si concentration possessed negative value. The tendency of each coefficient corresponds to the C, Si and Mn distribution caused by intercritical annealing. Moreover, the absolute value of the coefficient for the standardized C concentration was significantly larger than those of the other coefficients in the second principal component. The component represents the C enrichment of austenite due to bainite transformation.
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