Method of testing hardened steel articles utilizing the irreversible portion of the magnetization curve

Claim 1

A METHOD OF TESTING HARDENED FERROMAGNETIC STEEL ARTICLES WITHOUT DESTROYING THEM, COMPRISING THE STEPS OF DETERMINING THE INITIAL MAGNETIZATION CURVE FOR AN UNHARDENED FERROMAGNETIC STEEL ARTICLE CORRESPONDING IN CONFIGURATION AND TYPE TO THE HARDENED FERROMAGNETIC STEEL ARTILCE TO BE TESTED, OBTAINING FROM SAID INITIAL MAGNETIZATION CURVE STRENGTHS OF A.C. AND D.C. EXCITING MAGSUFFICIENT TO EXCITE THE ARTICLE TO BE TESTED THROUGHOUT A PREDETERMINED PART OF THE IRREVERSIBLE MAGNETIZATION PORTION OF THE SAID MAGNETIZATION CURVE CORRESPONDING TO A PARAMETER SELECTED FROM THE GROUP CONSISTING OF THE THICKNESS OF THE HARDENED SURFACE LAYER AND THE HARDNESS OF HARDENED STEEL ARTICLE, PROVIDING BOTH A SOURCE OF A.C. VOLTAGE HAVING A FIXED FREQUENCY AND A SOURCE OF D.C. VOLTAGE AND ADJUSTING SAID SOURCES TO OPERATE ON SAID IRREVERSIBLE MAGNETIZATION PORTION OF SAID MAGNETIZATION CURVE WITH THE UNHARDENED ARTICLE WITHIN THE MAGNETIC FIELD OF A REACTOR MEANS ENERGIZED BY BOTH SOURCES, PROVIDING A SERIES RESONANT CIRCUIT COMPRISING SAID REACTOR MEANS; CAPACITOR MEANS AND RESISTOR MEANS AND TUNING SAID CIRCUIT AT THE FREQUENCY OF SAID SOURCE OF A.C. VOLTAGE, AJUSTING THE OUTPUT OF AN INDICATING CIRCUIT CONNECTED TO SAID SERIES RESONANT CIRCUIT TO A NULL POINT WHEN SAID REACTOR MEANS HAS THE UNHARDENED ARTICLE DISPOSED WITHIN THE FIELD THEREOF AND SAID SERIES RESONANT CIRCUITS IS ENERGIZED BY BOTH SOURCES, REPLACING THE UNHARDENED ARTICLE WITH THE ARTICLE TO BE TESTED, AND OBSERVING THE OUTPUT OF SAID INDICATING CIRCUIT AS A MEASURE OF SAID PARAMETER.

Claim 2

A METHOD OF TESTING HARDENED FERROMAGNETIC STEEL ARTICLES WITHOUT DESTROYING THEM, COMPRISING THE STEPS OF DETERMINING THE INITIAL MAGNETIZATION CURVE FOR AN UNHARDENED FERROMAGNETIC STEEL ARTICLE CORRESPONDING IN CONFIGURATION AND TYPE TO THE HARDENED FERROMAGNETIC STEEL ARTILCE TO BE TESTED, OBTAINING FROM SAID INITIAL MAGNETIZATION CURVE STRENGTHS OF A.C. AND D.C. EXCITING MAGSUFFICIENT TO EXCITE THE ARTICLE TO BE TESTED THROUGHOUT A PREDETERMINED PART OF THE IRREVERSIBLE MAGNETIZATION PORTION OF THE SAID MAGNETIZATION CURVE CORRESPONDING TO A PARAMETER SELECTED FROM THE GROUP CONSISTING OF THE THICKNESS OF THE HARDENED SURFACE LAYER AND THE HARDNESS OF HARDENED STEEL ARTICLE, PROVIDING BOTH A SOURCE OF A.C. VOLTAGE HAVING A FIXED FREQUENCY AND A SOURCE OF D.C. VOLTAGE AND ADJUSTING SAID SOURCES TO OPERATE ON SAID IRREVERSIBLE MAGNETIZATION PORTION OF SAID MAGNETIZATION CURVE WITH THE UNHARDENED ARTICLE WITHIN THE MAGNETIC FIELD OF A REACTOR MEANS ENERGIZED BY BOTH SOURCES, PROVIDING A SERIES RESONANT CIRCUIT COMPRISING SAID REACTOR MEANS; CAPACITOR MEANS AND RESISTOR MEANS AND TUNING SAID CIRCUIT AT THE FREQUENCY OF SAID SOURCE OF A.C. VOLTAGE, AJUSTING THE OUTPUT OF AN INDICATING CIRCUIT CONNECTED TO SAID SERIES RESONANT CIRCUIT TO A NULL POINT WHEN SAID REACTOR MEANS HAS THE UNHARDENED ARTICLE DISPOSED WITHIN THE FIELD THEREOF AND SAID SERIES RESONANT CIRCUITS IS ENERGIZED BY BOTH SOURCES, REPLACING THE UNHARDENED ARTICLE WITH THE ARTICLE TO BE TESTED, AND OBSERVING THE OUTPUT OF SAID INDICATING CIRCUIT AS A MEASURE OF SAID PARAMETER.