高窒素オーステナイトステンレス鋼の組織と機械的性質に及ぼす時効の影響 (original) (raw)
Journal of the Japan Society of Powder and Powder Metallurgy, 2013
生体用準安定 β 型 Ti-5Fe-3Nb-3Zr 合金の機械的強度と生体親和性
Journal of the Japan Institute of Metals and Materials, 2012
Ti 29Nb 13Ta 4.6Zr (TNTZ) is a very attractive material for biomedical applications because of its low Young's modulus. However, this alloy contains a certain amount of rare metals elements. In this study, Ti Fe Nb Zr system alloys were developed by substituting Fe for Ta as the low cost b stabilizer, and the mechanical properties and biocompatibility of these alloys were investigated forˆve diŠerent compositions through thermo mechanical treatments. The micro Vickers hardness of the Ti Fe Nb Zr system alloy decreases with Fe addition up to 7 mol because of the suppression of the v phase precipitate. Subsequently, it increases by further Fe addition due to solid solution strengthening. Ti 5Fe 3Nb 3Zr (Ti 5 3 3) subjected to solution treatment (ST) shows the lowest Young's modulus among the other composition. In addition, the tensile strength of Ti 5 3 3 subjected to ST is higher than those of the annealed Ti 6Al 4V ELI and TNTZ subjected to ST. The specimens of the alloy implanted in the femoral epicondyle of rabbit are surrounded by new bone tissue formed with direct contact after 24 and 48 weeks from the implantation. It is considered that Ti 5 3 3 has relatively good biocompatibility with contact osteo genesis as compared with those of Ti 6Al 4V ELI and SUS316L stainless steel.
ボルト∙ナット締結体の疲労強度に及ぼすピッチ差の影響とその解析モデルの提案
Transactions of the JSME (in Japanese), 2015
The high strength bolts and nuts are widely used in engineering structures. To investigate the pitch difference on the fatigue strength of bolt, a slight pitch difference is considered between the bolt and nut. Here, the pitch of the nut is α μm larger than the pitch of the bolt. The fatigue experiment is conducted with varying pitch difference. The results show that the fatigue life is extended to about 1.5 times of the one of normal bolt and nut by introducing the suitable pitch difference under the high stress amplitude. According to the detailed observation on the fractured specimens, it is found that the fractured positions and the crack distributions vary depending on the pitch difference. To clarify the improvement mechanism of the fatigue strength, the finite element method is applied to calculate the stress amplitude and mean stress at each bottom of bolt threads. It is found that the finite element analytical model considering the incomplete nut threads is useful for predicting the crack initiation under different pitch difference introduced.
Journal of the Society of Materials Science, Japan, 2021
We studied the correlation between the evolutions of non-linear acoustic and magnetic properties and local misorientation on strain-induced martensitic transformation (SIMT) behavior in SUS 304 metastable austenitic stainless steel during tensile test. Two nonlinear acoustic characterizations; resonant frequency shift and high harmonic components with electromagnetic acoustic resonance (EMAR), parameters in magnetic hysteresis loops were measured. Furthermore, the evolution of microstructure was observed with electron backscatter diffraction (EBSD) was examined. EMAR is a contactless resonant method with an electromagnetic acoustic transducer (EMAT). This method enables not only to measure exact ultrasonic attenuation of measured sample but also to eliminate nonlinear acoustic effect between the sample and transducer. We used two type of axial SH wave EMATs, which transmit and receive axially polarized shear wave along a cylindrical surface of a circular rod, for ferromagnetic and non-ferromagnetic materials. The changes in non-linear acoustic and magnetic properties have good correlations with microstructural observations. They successfully capture SIMT behavior in a metastable austenitic stainless steel.
ITER トロイダル磁場コイル用 Nb3Sn 超伝導素線の量産と品質管理
TEION KOGAKU (Journal of Cryogenics and Superconductivity Society of Japan), 2012
Superconducting conductors are applied in the toroidal field (TF) coils, poloidal field coils, and central solenoid (CS) in the ITER. The Japan Atomic Energy Agency plans to procure 25% of the TF conductors and 100% of the CS conductors. Mass-produced Nb 3 Sn superconducting strands for TF conductors have been supplied by two manufacturers since 2008. The total length of the strands is approximately 23,000 km; thus, quality control is extremely important. A statistical process control has been adopted in order to reduce the dispersion of strand performance, and stable performance of the mass-produced strands was achieved. Both manufacturers improved the fabrication yield through mass production. Approximately 72% of the Japanese share in TF strands has been produced as of October 2011.