Cracks during Welding of Cast Inconel to Forged Inconel 1

[mantou1979]

Hi all, I am new here.

Currently I have a project that requires me to weld a piece of Cast Inconel 718 to another piece of Forged Inconel 718 using plasma welding.

After welding, tends cracks appear at the edge of the weldment only the Cast Inconel side, but never at the forged side of the weldment.

Has anyone ever encounter this problem before and is there a way to minimise it? Thanks.

 

[stanweld]

I have experienced similar problems, resulting from low melting eutectics along the grain boundary. Deoxidizing practice in casting manufacture was the cause. In the worst cases, the castings had to be remade; they wee simply unweldable.

 

[metengr]

mantou1979;
See below for papers related to cracking in the weld HAZ of cast Inconel 718;

http://stinet.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADD148003

http://cat.inist.fr/?aModele=afficheN&cpsidt=4369533

http://doc.tms.org/ezMerchant/prodt...07-2005/$FILE/MMTA-0207-2005F.pdf?OpenElement

 

[mantou1979]

Everyone thanks.

But does anyone know how to prevent this cracks from happening or at least minimise them?

 

[metengr]

mantou1979;
There is one approach that might help you. Considering the sensitivity to cracking in the partially melted zone next to the weld region, I would attempt to reduce any restraint that could lead to tensile stresses in this region. You might need to re-configure the weld or its location to reduce the effect of restraint during and after welding.

Also, check the grain structure of the casting. It might be that the casting has a coarse grained structure that will increase susceptibility to grain boundary and fusion zone liquation cracking from welding.


Source; Welding Metallurgy by Sindou Kao, page 376

 

[deanc]

Stumbled onto this link today and remembered your post.

http://www.specialmetalswelding.com/publica/joining.pdf

Gotta love the net.