[TheForge] A36 vs 1018

[David Childress]

In our group there is much debate about A-36.  I know from job
experience ( engineer in a tool & die shop) something about a36.  The
fact is that A36 is made from scrap and is junk.  Most of the specs
are max without min. or min. without max. and there are many metals
that are not mentioned  at all that may or may not be present.  Our
forgemaster really dislikes A36, but when a found a a distributor that
was willing to sell 1018 to us at his cost the cost still freaked most
of us out ( about 185% of A36 cost).

I have been told that the lead and copper in A36 is what makes it hard
to forgeweld.  These are allowed for ease of machining, but due to the
processing of A36 they are not necessarily evenly distributed.  So
some places will forge weld and maybe 6" down the bar it will not weld
at all.

I had a diemaker  tell me that once they got a piece of A36 that he
could not drill a hole thru.  some other Die maker cut the peice up
and found a piece of coil spring that had never melted at the end of
the attempted hole.  As another example my daughter made her first
knife ( letter opener) out of A36.  Being impatent as she always is (
13 yrs old)  when she got it shaped she threw it in the quench tank.
We could not sharpen it (Hrc 68).
A36 is just like that.  It is good enough for most structural uses,
but you can never tell what it will be like.

David Childress
Rocky Forge Blacksmith Guild

On 2/11/09, Paul N <crosspein at sbcglobal.net> wrote:
> OK, I've been reading that PDF that Frosty posted a couple weeks ago,
> and I'm about halfway through my first pass at it. (It will likely
> require more than 1 to understand it)
>  (It was this one: http://www.feine-klingen.de/PDFs/verhoeven.pdf)  And
> many thanks for posting that. It's just the kind of description I had
> been looking for.
>
> We should probably start "Frosty's Book Club" discussions, as I'm sure
> that there are things I think I understand, but that I've
> mis-interpreted. But that's a different story.
>
> I'm finding the "book" very enlightening, and not horribly difficult to
> read. (Although anything even approaching an hour at a time seems to
> stimulate the auto-nap response) I had taken a metallurgy class in
> college over 30 years ago, but studying to pass a class is totally
> different from studying to LEARN. So while I've been exposed to this
> stuff before, this time is different and enlightening.
>
> OK, now for my real question:
>
> I've occasionally been stymied while trying to forge weld with hot
> rolled A-36 steel, and since it occurred last night while I was
> demonstrating how to make a basket handle (using 6 pcs of 1/4" round
> A36) I thought maybe it's time to ask. I've made dozens of these, so
> it's not exactly a new process for me.
>
> My problem last night was that the person that asked for the demo had a
> pretty hollow (coal) fire, but I thought that I'm finally getting pretty
> good at this, so why not go ahead with it as is. The first weld, with
> all the pieces kind of loose, went off without a hitch. Welded nicely on
> the step of the anvil. But when I went to the other side, which I've
> always found easier as it's more stable, it didn't take. That's not
> really a problem in itself. I've been here plenty of times.
>
> What became an issue is, now even after correcting the fire, I can't get
> it to weld. After about 4 attempts, the ends are now hopelessly
> distorted and difficult to repair and I abandoned my demo in
> frustration. BTW, I was using straight 20-mule team borax as a flux.
>
> So, what happens to the metal? Does it pick up contaminants? Did it
> de-carburize (there was a little sparking, but not what I'd consider
> significant, and even if it did, wouldn't the lower carbon level make it
> easier to weld? )
>
> In the past, when I've had a failure like this with A-36, Usually end up
> cutting back the ends to get a successful weld, so I'm expecting that
> there has been some metallurgical transformation here. So I'm wondering
> if anyone knows what that change might be.
>
> Since I'm feeling a little more knowledgeable now, I've looked at  the
> chemical compositions of 1018 and A-36, and aside from the slightly
> higher carbon content of A-36 (about 0.25% C vs 0.18% C) there isn't all
> that much difference, chemically. Perhaps it's the inherent grain size,
> and with a little annealing the A-36 would behave better?
>
> (Using references from:
> http://www.benjaminsteel.com/Technical%20Data/A-36-properties.htm and
> http://www.geocities.com/haimanaua/htdocs/steels/1018.html )
>
> So, can anyone explain the differences in behavior in A-36 and 1018 when
> it comes to forge welding?
>
> thanks,
> **pn
>
>
>
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