Recently, the demand which wants to control the health by measuring body information such as blood pressure, body temperature, and pulse number increases. In jogging and under walking, there is a case in which the healthy subject harms the health. In this paper, the method for noninvasively measuring pulse wave using strain gauge is proposed and the development of the equipment was tried. As the result, this equipment measured ejective wave by the ejection of the blood from the heart, tidal wave from the bifurcation of arterial vessel, incisura wave (dicrotic wave) by the closure of aortic valve. Amplitude and shape of the signal waveform from 3 channel sensors are different. In the measurement by this equipment, the waveform of tidial wave and dicroric wave has appeared clearly in comparison with the equipment of the marketing. In addition, the signal waveform is variable in the existence of the motion. AI value and attractor were clarified from the data. The attractor of rest condition and exercise condition can be clearly distinguished.

View full abstract

The effect of hydrogen on low cycle fatigue life and properties has been examined on S10C, which has limited amount of pearlite. Then the results have been analyzed with regard to the conditions and distributions of hydrogen. Discussion has been further made on the essentials of the degradation by hydrogen absorption. Degradation by hydrogen is not usually perceived in low carbon ferritic steels;A large part of hydrogen is discharged during the arrangement before fatigue test, because of little amount of pearlite that can retard the diffuse-out of hydrogen. Minimizing the hydrogen emission by devising the experimental method, degradation of fatigue life has been successfully detected. When the hydrogen in matrix gasifies at inner part of the specimen along the interface between matrix and inclusion, the high-pressure hydrogen gas atmosphere assists the initiation and propagation of fatigue crack. Hydrogen absorption also suppresses the Bauschinger effect and enlarges the stress amplitude. This is not the direct cause of hydrogen damage. Hydrogen may stabilize vacancy that is produced by cyclic deformation, and enables micro-voids formation and further coalescence of them. Hydrogen degrades the fatigue life through stabilization of vacancy.

View full abstract

A lower limit of fracture toughness distribution is shown to be controlled by crack arrest ability. The expression of fracture probability by Beremin is modified by taking account of the lower limit. The lower limit is suggested to vary depending on the difference of transition temperature between initiation and arrest in terms of fracture toughness.

View full abstract

The SCC (Stress Corrosion Cracking) susceptibilities of Inconel alloy 600 weld metals of various chemical compositions have been investigated for the specimens in the as-welded states and those subjected to the heat treatment consisting of stress relief annealing (SR) for 72 ks at 893 K and subsequent ageing (LTA) for 720 ks at 673 K. The weld metal specimens were cut from the shielded metal arc welds of C content=0. 03-0. 11mass%, Nb=1. 22-4. 39mass%, Cr=13. 81-21. 44mass%, and P=0. 011-0. 031mass%. The SCC susceptibility of the weld metals was evaluated from the maximum depth and number of cracks occurring on the CBB (Creviced Bent Beam) test in high temperature pressurized water. Their intergranular corrosion resistance was also evaluated based on the double-loop electrochemical potentiokinetic reactivation method. The SCC susceptibility of the weld metal showed a strong dependence on the intergranular corrosion resitance and the hardness;the weld metal became more susceptible to SCC, as the hardness was increased and the intergranular corrosion resistance was impaired. The increases in Cr and Nb contents improved the intergranular corrosion resistance, whereas the increases in C and P contents impaired it. The hardness increased with C and Nb contents, but it was almost independent of Cr content. In particular, the weld metals subjected to the SR+LTA treatment were hardened remarkably with the increase in Nb content owing to the precipitation of ?'phase (Ni3Nb) during the SR treatment in interdendritic areas enriched in Nb. The addition of P shrunk the interdendritic area hardened by the ?'precipitate, resulting in the decrease in hardness. Thus, the SCC susceptibility of the weld metal was improved as the C content was decreased and the Cr content was increased, while the effects of the increase in Nb content depended on the C content;i. e. , it improved the SCC susceptibilities of the weld metals of low C content but impaired those of high C contents. The increase in P content, though decreasing the intergranular corrosion resistance, improved the SCC susceptibility of the weld metals of high Nb contents after the SR+LTA treatment by reducing the hardness.

View full abstract

In oil storage tanks, corrosion rate of the steel plate in the bottom part gives important information to the safety management. The rate of corrosion is defined to be an amount of decrease of thickness divided by the service year. However most of the tanks rarely have the data on thickness of initial state to estimate the thickness decrease and usually nominal thickness of plate is used instead of it. The discrepancy between the nominal thickness and the actual thickness is often found to be significant.
In this report, a method is proposed to estimate the mean value and the standard deviation of a normal distribution to which the initial thickness is subjected using the data measured at the time of periodic inspection.

View full abstract