Eddy Current Testing

Rate of change in resistivity with grain size is a deciding factor, Do you have any resistivity of grain size graph? If yes please post it,

no such data is available, is there any other way out

thanks for the inforamtion

Good answer as usual RHABE,

The only thing I could add is to independently verify your results by other methods such as visual appearance, sound when struck or otherwise sonically excited, ultrasound, Xrays etc then cutting the samples that appear suspicious and a few that seem good and etching them to reveal grain structure. You will need statistically significant quantities.

If diagnostics above visual and physical and resistance / simple inductance are too expensive, just cut more samples.

For resistance and inductance tests decide on consistent test points and methods of injecting physical current / measuring voltage and resonance. To overcome small variations try and overwhelm the differences with strong amounts of current. For inductance tests try and fiddle around with frequencies. With luck you may find a sweet spot that gives a pass / fail point. Finally ensure you account for temperature and temperature rise.

Please report back.

thanks , we had tried to use ultrasonic but could not get satifactory results that is why now we are thinking of using eddy current. will add more information later after conducting more trials.