| 摘要 |
PURPOSE:To estimate breakage life with a simple method non-destrictively by applying the specific electric resistance of a high temperature member to creep damage ratio and specific electric resistance in a creep test at a corresponding temperature. CONSTITUTION:The relation between specific electric resistance Rp at test temperatures, 550, 550, and 600 deg.C and creep damage ratio is shown in the figure. The specific electric resistance Rp shows good correlation with the creep damage ratio at any of the heating temperatures with higher creep damage ratio followed by lower specific electric resistance. Furthermore, the specific resistance Rp depends on the heating temperature, and it has a tendency that with higher temperature the rate of fall in the specific electric resistance is higher. On the other hand, the rate of fall in the specific electric resistance Rp is large up to creep damage ratio, phic=0.5 approximately, and over this value the fall is small. Now, the value phic that is nearly 0.5 is taken as a target value, and when the specific electric resistance goes over this value, the high temperature member is monitored periodically or constantly along with one of one-destructive testing methods such as ultrasonic flaw detection, X-ray test, magneic flaw detection, dye check in parallel with the electric resistance method, and high accuracy life estimation becomes possible. |
