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RE: Magnetized steel

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John,

In general, the process for demagnetizing anything is called degaussing.
The Navy degausses entire ships.  Missiles have built in degaussers.
Missiles can become magnetized by the friction from air contact.

I have never heard of a problem with welding magnetized steel, however, you
can develop an arc blow problem just by the placement of the ground relative
to the arc (this is kind of a magnetic steel issue).  You need to find out
if arc blow is the specific problem.  I would suggest you find out the exact
nature of the problem.  There is a great article in Section 3.2 in The
Procedure Handbook of Arc Welding by Lincoln Electric.  It gives you the
symptoms and solutions.  

You will need to determine what the process is, and what the exact problem
is.  If it is arc blow, you need to find out if it is a back blow problem or
a forward blow problem.  If it is a submerged arc, you can't view the
direction of the blow directly, but you can infer the type of problem by the
symptoms (i.e. undercut, increased penetration, decreased penetration, etc.)

As Peter Higgens noted in his post, it is more of a problem with DC versus
AC welding.  Peter's additional advice about contacting Omer Blodgett is
sound.  Omer IS the master.  I spent a week in Euclid, Ohio in 1978 studying
welding under the masters at Lincoln Electric enough to know my limitations.

Regards,
Harold Sprague


> -----Original Message-----
> From:	John Dewar [SMTP:jfd(--nospam--at)freese.com]
> Sent:	Monday, May 15, 2000 2:21 PM
> To:	seaint(--nospam--at)seaint.org
> Subject:	Magnetized steel
> 
> We have a project where we're welding steel plates to an existing steel
> gate
> at a dam.  The existing steel has somehow become magnetized at some
> portions
> of the gate, making the welding very difficult.  The contractor wants a
> change order because the welds are coming out defective and taking longer.
> We've found some references to magnetized steel in the literature, but no
> solutions to the problem.
> Does anyone have any experience with magnetized steel and how to
> demagnetize
> it?  Thanks in advance.
> 
>