Cyclic Stress Measurement Method Using Electrodeposited Nickel Foil

－Study of Measurable Stress Range and Ambient Temperature－

Abstract

　　　Relationship between measurable stress range and the ambient temperature of the cyclic stress measurement method using the grain growth of electrodeposited nickel foil was examined in this report. Since recrystallization temperature measured by the differential scanning calorimetry was 270 ℃, it can be said that the applicable upper limit is 250 ℃. However, it is necessary to pay attention for application to a machine element that subjected to high temperature for a long time, such as 200 ℃ × 120 h, since recrystallization is accelerated by keeping high temperature. Since a mechanical energy required for grain growth is increased with decreasing ambient temperature, the nickel foil was applied for the low temperature environment (373K) than the traditional report (473K). Maximum shearing stress that grains grown in 373K was about 1.5 times larger than that in 473K. The calibration equation between the grown grain density, maximum shearing stress, number of cycles and ambient temperature was obtained based on the experimental data. From this equation, the range of measurable shearing stress at various ambient temperatures was calculated and compared with the copper foil. Nickel foil was possible to measure the high shearing stress at low temperatures as compared to the copper foil.