The austenitic heat-resisting steel will be aged and damaged by creep after long-term service under high temperature and high stress.This process is accompanied with remarkable change of magnetic property due to phase transformation in said steel.In addition

the precipitation of metallic carbides and σ phase after service under high temperature makes Cr depletion areas appeared around the precipitated phase

resulting in remarkable change of the composition in alloy

and makes Ms (initial temperature for formation of Martensite steel) to rise

and the Martensite transformation occurred after cooling to room temperature

leading to remarkable change of magnetic property in heat-resisting steel.For this

through measuring the Martensite phase composition in alloy

the evaluation of aged degree for austenitic heat-resisting steel after long-term service under high temperature can be carried out by adopting the magnetic property measuring method.