Thursday, April 19, 2012

Is Arc Weld Forgeable?

Is Arc Weld Forgeable?


Is arc weld forgeable? In other words can you heat a arc weld and change its shape and still maintain the integrity of the weld. I'm talking stick weld using rod for low carbon steal, a36, 1018, 1045
thanks for your help.
Jjim Shaver

Hi Jim
The short answer is yes if it is a good weld to start with.

Now there are some problems. Arc welding tends to create a bit of an undercut right at the edges of the weld. When you forge over top you flatten out the weld but the undercut stays. This can become a crack with successive forgings. It also usually stays visible which I find unsightly and indicates to me that the piece has been electrically welded.

Higher carbon content steel may develop a fracture at the undercut more easily than low carbon mild steel, if it is worked on the cold side. Although high carbon may actually benefit more from the forging process than lower carbon steel especially if it was not preheated when welded.

I would suggest (of course depending on the application) using a rod that doesn't undercut the steel very much. 7014 comes to mind but this depends on the steel and your welder (dc is better than ac) and your welding skills.

Alternatively if you mig or tig weld there is less undercutting and you can forge directly with little issue, both in strength and visibility of the weld.

Of course try a few practice pieces and I recommend forging more on the hot side than the cold side of temperatures and properly prep your welds with V groove and multiple passes as is appropriate for strength. Play with your machine setting until you get the least undercut with the weld.

I hope this helps.
David Robertson
Artist Blacksmith