A new non-destructive method for estimating the remanent life of a turbine rotor steel by reversible magnetic permeability

Nondestructive evaluation for remanent life of modified 9Cr–1Mo steel by reversible magnetic permeability

“…E(H 0 , h 0 ) is given by the time derivative of magnetic flux, which is proportional to the magnetization. E(H 0 , h 0 ) can be expressed as follows [6]:…”

“…To measure RMP, the specimens were magnetized by a surface type probe with a ferrite yoke. The probe is constructed with a pick-up coil, an AC perturbing coil, and a DC magnetizing coil [6]. The DC magnetic field was produced via a sinusoidal wave current of 0.05 Hz with a maximum applied magnetic field of 14 kA/m.…”

“…The slow varying magnetic field was measured via the current using the voltage across a shunt resistor of 1 O. The RMP was measured during a cycle of slow varying field as a function of current along the sample axis using an I/O acquisition board [6].…”

“…Many researchers [4][5][6][7] have been interested in the destructive and nondestructive measurement methods for examining microstructural changes and component damage in order to ensure safe operation of steel structures, such as turbine rotors and reactor pressure vessels. Destructive methods are reliable and widely used for estimating the degradation and the remanent life of a material.…”

“…Thus, a nondestructive evaluation technique to determine the remanent life of material is necessary. Although various nondestructive methods have been studied, the development of a nondestructive technique to quantitatively estimate material degradation has not been completed to date [4][5][6].…”