EMAT measurement of ductile cast iron nodularity
US5714688A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 30, 1994 |
| Grant date | Feb 3, 1998 |
| Priority date | — |
| Expiry date | Sep 30, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2291/044
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method of examining a ductile iron casting to determine a percent of nodularity present in the casting uses an electromagnetic acoustic transducer (EMAT) system to determine a time-of-flight of an ultrasonic shear wave pulse transmitted through the casting at a selected location, from which a velocity of sound in the casting can be determined. The ultrasonic shear wave pulse created and sent through the casting experiences several internal reflections within the casting, and the absolute delay time for both second, T.sub.DELAY1, and third, T.sub.DELAY2, multiple reflections are used to determine the time, T.sub.DELTA, required for the ultrasonic pulse to travel through twice the thickness, t, of the casting at said location. The velocity, V.sub.SHEAR, of the ultrasonic shear wave pulse through the casting is calculated from T.sub.DELTA and a measurement of the thickness, t, of the casting at the location being inspected. The percent of nodularity of the casting is determined from a pre-established relationship between the calculated shear wave velocity, V.sub.SHEAR, and the percent of nodularity for ductile cast iron.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.