MATERIAL CHANGED STATE TO PERMANENT MAGNET

[sudac]

Please if someone has experiance with following.

We have bar diameter 80 mm and lenght 1250 mm, material is EN 34CrNiMo6 (AISI 4337/4340).
State of material is quenched and tempered.

But after machining on lathe it is acting as permanent magnet.

Is that normal for this type of material, or is it possible that it was not heat threated?

Best regards

Šime Voki? mech.eng.

 

[lgearhart]

Such steels are ferromagnetic, and will pick up magnetism. Did you use a magnetic workholding fixture when you machined it, or did you test the bar with magnetic particle inspection? If so, then you could easily have magnetized it.

Often after MPI one will degauss the parts to eliminate the residual magnetism.

 

[ornerynorsk]

The machining process will almost always magnetize your workpiece. This is very normal.