Remaining strength of pre-fatigued and dynamically-tensile-fractured free-cutting steels, SUM24L and SUM23 (JIS G 4804:2008) were degraded than those of virgin steels, respectively. In order to investigate the cause(s) of the degradation, the pre-fatigued and dynamically-tensile-fractured specimen is cut along the longitudinal axis, polished and observed by a scanning electron microscope (SEM). Neighboring fractured surface, some MnS grains are penetrated by steel matrix. This phenomenon can induce easier reduction of cross-section. Therefore, the penetration is a candidate of the cause(s) of the strength degradation.

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In this study, we will introduce the phenomena of residual magnetization change during plastic deformation in ferromagnetic metals. Since dislocations behave as the pining cites of magnetic domain walls, and vice versa, plastic deformation induces the residual magnetization on hysteresis curve into anhysteresis. Under no magnetic field, ferromagnetic metal will be demagnetized during deformation. Also, under certain magnetic field, it will be magnetized. Since additional plastic deformation can be estimated from magnetization change, gradual plastic deformation during pressing or machining can be controlled by using this method. We will emphasize that this evaluation of the additional plastic deformation is quite unique property of the proposed method.

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Voids are formed in CFRP laminates by different curing pressure conditions, and they could cause strength reduction. In our previous study, we developed a strain measurement method using fiber location search by image correlation for pictures taken by a scanning electron microscope (SEM). The in-situ three point bending experiment was carried out under SEM, using CFRP specimens with different void volume fraction (V_v) prepared by different curing pressure conditions. The microscopic strain fields in 90° layers under transverse tensile loading were obtained by the above-mentioned strain measurement method, and the relationships between voids and strain fields were discussed in detail. The experimental results showed that strain concentrations occur around voids. Especially voids aligned perpendicular to load caused high strain concentrations, while voids aligned parallel to load caused low strain concentrations.

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TMEIC has developed a non-contact sensing system of material grain size using a laser ultrasonic method. The features of this system are: non-destructive sensing, long stand-off distance, and high frequency ultrasonic suitable for detection of microscopic structures. The experimental result shows good coincidence between measured Ferrite grain sizes by this system and by the microscope observation. In addition, the measured Ferrite grain size showed good correlation with the tensile test results.

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Authors have studied defect imaging technique for a thin plate using a scanning laser source technique, in which Lamb waves are generated with laser emission and received by ultrasonic transducers fixed on the plate. This study described full non-contact imaging technique with air-coupled sensors in the low frequency range of 40 kHz. Moreover, fast defect imaging system using analog peak detectors were developed. Although real-time imaging of defects in a thin plate was realized, unwanted images were obtained in high speed scanning due to reverberations in the plate.

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The probability of Si grain refinement in hypereutectic Al-25 mass% Si alloy is examined by a compression test of cylindrical specimen (φ15xh15) at over eutectic melting point of 577 ℃. The tested condition comprises a combination of temperatures, T, of 580 and 590 ℃, compression rates, ν, of 5, 25, and 125 mm/min, and compression stroke, Oh, of 5, 10, and 12 mm. The viscosity and the shear rate are observed in the range from 0.2 MPa・s to 3 GPa・s and in the range from 2 ms^<-1> to 2 s^<-1>, respectively. The finer Si grain is obtained in cases of lower tested temperature, higher compression rate, and larger compression stroke, i.e., in case of T=580 ℃, ν=125 mm/min, and Δh=12 mm. The relations between Si grain size and shear rate for each tested temperature are summarized in a simple line on a single logarithmic plot. The process of Si grain refinement can be associated mainly with applied shear force.

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The aim of this study is to investigate the rheological behavior for a semi-solid forming of Al-25 mass % Si alloy, i.e., hypereutectic Al-Si alloy, using a self-made parallel-plate drop-forge viscometer. Drop-forge experiments show individually the features that the viscosity decreased in the early increasing shear rate stage and subsequently the viscosity turned to increase as the shear rate decreased. Thus, the viscosity takes a minimum around the maximum shear rate. The summarized behavior between the viscosity, μ, and the shear rate,γ^^., can be described by a power-law model of μ=1.78×10^7γ^^.^<-1.5> Pa・s. The decrease in viscosity accompanied with the increase in the shear rate depends on both rises in the temperature and the applied force, not the duration of shear.

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Aluminum honeycomb has superior properties which is light weight, high rigidity, energy absorption more than bulk aluminum. In present the aluminum honeycomb sandwich panel (AHS) is used for structural materials such as aerospace panel and house materials. The AHS is generally made from honeycomb core and aluminum alloy panel. These honeycomb core and panel are bonded with the bond. The bond is often not good for heat resistance or recyclability in some situations. The aim of this study is to clarify microstructure and bonding property to manufacture AHS by melt drag process without the bond.

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Characteristics of compactions of Cu 60 mass%-Zn 40mass% brass (60Cu-40Zn) chips and their extruded materials were investigated. 60Cu-40Zn chips were consolidated by cold compaction (C.C), compaction and sintering (C.S), and spark plasma sintering (SPS). Relative density of C.C billet, C.S billet, and SPS billet were 77.3 %, 98.6% and 99.6 %, respectively. In the case of C.C billet heat treated at 973 K, there were zinc oxides at primary particle boundaries by zinc evaporation during heat treatment. The elongation of the extruded material used C.C billet was the lowest in this experimental materials. There were many cracks in the C.C billets extrusion because of pure particles bonding by zinc oxide. In the case of C.S and SPS billet extrusions, good primary particle bonding were occurred. High density billet for reducing zinc vaporization was needed to make a P/M extruded brass with suitable ductility.

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The use of adhesively bonded joints has been expanding to many application fields such aircrafts, automotive and electronic devices, and the service condition has recently become severe. Hot-wet condition is especially crucial for resins because adhesives are often used in such environment. But little information is available. Therefore, in this case the degradation of resins used for adhesives should be examined thoroughly. In this study, the mechanical properties for example modulus and strength of resins used for adhesives in hot-wet condition were investigated experimentally.

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