Fred W Tatar

US Patent:

46927018, Sep 8, 1987

Filed:

Dec 13, 1984

Appl. No.:

6/681280

Inventors:

Robert E. Dundas - Duxbury MA
Fred W. Tatar - Dedham MA

Assignee:

Factory Mutual Research - Norwood MA

International Classification:

G01N 2782
G01B 724

US Classification:

324240

Abstract:

In a method for testing steam turbine rotors for embrittlement to determine which rotors to retire and which rotors to continue in operation, a varying magnetic field is applied to the rotor in a waveform to produce a detectable Barkhausen effect in the flux density developed in the rotor. The resulting Barkhausen burst of pulses is detected and is displayed on an oscilloscope. In addition, the pulse amplitude distribution of the pulses in the burst is plotted. The oscilloscope display and the pulse height distribution curve are compared with corresponding representations of the Barkhausen effect produced from a test sample known not to be embrittled, or from the rotor itself at a previous time, to make a determination of whether the rotor has become embrittled and whether to continue operation of the rotor.