Untitled

Degradation Evaluation of Mechanical Property for Modified 9Cr-1Mo Steel by Reversible Permeability

“…The variation in yield strength normalized while those of a virgin sample decreased significantly for a short aging time, but the change becomes small at a long aging time. The decrease in magnetic and mechanical properties should originate such that the magnetic and mechanical softening of the matrix is likely to affect the properties of the sample more than the hardening of the grain boundary by carbide precipitations [4,11].…”

“…Many researchers [3][4][5] have been interested in nondestructive measurement methods for examining microstructural changes and component damage in order to ensure safe operation of the steel structures, such as turbine rotors and reactor pressure vessels. Although various nondestructive methods have been studied, development of a nondestructive technique to quantitatively estimate material degradation has not been completed to date [3][4][5].…”

Nondestructive Evaluation of Thermally Degraded 2.25Cr-1Mo Steel by Electrical Resistivity Measurement

“…10,11,20) Measurement was carried out at room temperature consistently fixed at 20 C. A computer-controlled direct current source was used to supply current AE1 A to the specimen and the voltage was measured to 1nV using nano-voltmeter. As the interval between voltage output leads can lead an error in electrical resistivity values, 10) a fixture with constant terminal interval was used. A sheet-type specimen of 60 mm in length, 10 mm in width, and 2 mm in thickness was used to measure electrical resistivity.…”

“…Since it is difficult or practically impossible to obtain specimens for mechanical testing without damaging the structure in operation, many researchers have attempted to evaluate the damage of structures nondestructively, for insitu monitoring. [10][11][12][13] Electrical resistivity, 10,11) magnetic, 12) and ultrasonic 13) methods are currently used for nondestructive evaluation of structures. Electrical resistivity method, which was widely used for evaluating material properties like precipitation behavior, [14][15][16][17][18] has recently been applied in the field of non-destructive evaluation of structure.…”

“…Although some researchers 10,11) have reported changes of electrical resistivity in the degraded structure, the correlation between electrical resistivity and microstructural changes in the thermally degraded materials is lacking.…”