This standard specifies the eddy current attenuation measurement method for pure metal resistivity and residual resistance ratio, which is suitable for pure metal specimens with a diameter of less than 20mm and a resistivity between 0.1 and 10.162μm. The term includes the eddy current attenuation time constant [tau], which is the time required for the eddy current signal strength to decrease to 1/e of the original signal strength, and the residual resistance ratio R.R.R, which represents the ratio of the resistivity of the material at 273.15K to the resistivity at 1.2K. The principle of the method is to measure the eddy current induced in the specimen by removing the magnetic field after the magnetic field is established in the primary coil. The attenuation rate depends on the resistivity and geometry of the specimen.