Magneto acoustic emission apparatus for testing materials for embrittlement

US4912411A · kind A · utility

Assignee

• The United States of America as represented by the Administrator of the National Aeronautics and Space Administration · US

Inventors

• Sidney G. Allison · Poquoson, US
• Min Namkung · Yorktown, US
• William T. Yost · Newport News, US
• John H. Cantrell · Williamsburg, US

Key dates

• Filing date: Jun 23, 1988
• Grant date: Mar 27, 1990
• Expiry date: Jun 23, 2008

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N27/725
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A method and apparatus for testing steel components for temper embrittlement uses magneto-acoustic emission to nondestructively evaluate the component. Acoustic emission signals occur more frequently at higher levels in embrittled components. A pair of electromagnets are used to create magnetic induction in the test component. Magneto-acoustic emission signals may be generated by applying an AC current to the electromagnets. The acoustic emission signals are analyzed to provide a comparison between a component known to be unembrittled and a test component. Magnetic remanence is determined by applying a DC current to the electromagnets, then turning the magnets off and observing the residual magnetic induction.