Magnetic Properties of ASTM A108

[ndtkansas]

We are trying to perform magnetic particle inspection of A108 material. After we send current through the parts, we are finding that there is no residual magnetism. The material does have some chrome and nickel (0.13 and 0.06) and copper (0.16) but shouldn't influence the magnetic properties should it?

 

[EdStainless]

You are probably not providing a high enough field to effectively magnetize the parts.
OR
Just because a material is ferromagnetic does not mean that it will retain magnetism. This material may be clean enough and annealed well enough so that it has near zero coercivity, and will not stay magnetized when the field is removed.

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Plymouth Tube

 

[blacksmith37]

You inspect while the current is flowing.

 

[ndtkansas]

The inspection technique is validated by use of a hall Effect Probe - there is 40-50 gauss at the current setting. For a material to be ferro-magnetic it must retain magnetism otherwise it wouldn't be ferro-magnetic. The part is tube shaped and is 3" long and approximately 3/4" in diameter.

 

[blacksmith37]

I assumed you were looking at long bars. For a part 3" X 3/4" ,would a permanent magnet technique be more convenient ?

 

[Eddycurrentguy]

A permanent magnet may be more convenient, but probably won't provide enough field saturation to achieve the desired affect.