Working with some hardox armor plate. Why is it magnetized?

By Kix

Date 05-25-2007 17:36

What is making this stuff magnetic? This is before welding on it. We are cutting it on a laser and it's put on the table via suction cups, if you put a small piece on the table it sticks a bit cause it's magnetized. I know some big pieces of plate are picked up with huge magets, but i thought once the energy is cut then the magnetism is done. Are these plates holding on to their magnetism from the mill? And what is in the stuff that makes it hold magnetism better then another type of steel? I'ts just an A500 grB Group II steel.

By new tito (***)

Date 05-25-2007 18:33

Don't know specifics on that material, but there are numerous materials that hold a magnetic field even after the field is terminated. This is called....residual magnetism.

Don't get me lying, but it has to do with the iron content, from what I remember from MT training. Alot of your higher carbon steels are hard to magnetize, but the are also hard to demagnetize.

Not sure what could be causing it. You can get a Gauss meter (measure magnetism) to check it when it arrives to find out if indeed it is magnetized from your supplier. Maybe possibly getting an electrical current passed thru it on your set up. Electrical current can cause a part to get magnetized also.

By CWI555

Date 05-26-2007 02:28

http://hyperphysics.phy-astr.gsu.edu/hbase/solids/hyst.html
This should answer your question.

By DaveBoyer (*****)

Date 05-26-2007 03:18

My guess is it probably got magnatized in manufacturing or handling, if this is causing a problem You will need to de magnatize it. This is done with an alternating current field. How big is the stock before it is laser cut?