Weldind Cast Iron

[Chuck]

This is an endless debate...the subject of much
confusion and varying opinions.
Can cast iron be welded, or not?

Ask this question, and you will invariably get
a different answer from every single person you
ask.

If Lincoln Electric says it can be done, it's
pretty obvious to me that it *can* be done.

The results may or may not be strong and last
long.

The master mechanic up at the Monticello
Railroad Museum in Monticello, Illinois insists
that any and all attempts at welding cast
iron draw the carbon out, and makes for an
overly brittle joint.

He outlines the method that railroads used
to mend large castings such as steam cylinder
castings on steam locomotives. He talks about
building a container around the casting and then heating it for days with a charcoal
fire. Then, a team of men go about brazing,
each man gently uncovering the heated area by
pulling back the asbestos blanket and brazing
a bit until he can't stand the heat any longer.
Then, the next man takes over...

Once the brazing is completed, then the casting
is allowed to slowly cool over several more days. He insists this is the only way.

I tend to think he knows what he is doing because there are examples of his work in
daily use on that little railroad.

No doubt modern welding techniques have been
developed that can and do work on cast iron.
Is the joint strong enough to hold up to the
application? My opinion of it is that for
low-strength needs such as parts of an Edison
phonograph, that one can surely get away with
welding in some form or another. Is it really
proper? Does it draw the carbon out?
Is it as strong as a brazed joint?

I once had an old bench vise that got broken
and a buddy of mine welded it. I used it for
a while, but then one time when I was wailing
away at a part clamped in it, the weld joint
broke...so there ya go.

I tend to go with what the old-timers say
about brazing cast iron.

Chuck

[adrianf]

Hi Guys just my 2c worth. I am a welder and weld cast iron on a daily basis. I will have to say not all cast iron can be welded though depends on how much carbon is included.

Adrian