Post-weld Heat treatment specs for Hi-temp alloys

[cmarinelli]

Hello everyone,

My company is reverse engineering a turbine engine component that consists of a small plate onto which two bolts are welded. The plate is most probably Inco 718, and I believe the bolts are Inco 718 or A286 (lab analysis pending).

My question is:

Are there separate specs governing post-weld heat treating, or are the normal heat treat specs commonly employed (i.e. AMS-H-6875 or AMS 2759/x).

Is it common to age the weld filler material to obtain maximum properties? Must you solution heat treat or anneal the weld first?

Anybody know a good spec or reference regarding welded assemblies of high temp alloys like Inco 718, Hastelloy, A286, etc.?

Thanks in advance for any assistance you can provide.

Regards,
Chris

 

[mcprofusion]

Good question..i did some quick research and found this:

718 welded in the aged condition > The excessive softening of the HAZ due to solutioning can result in cracking in the areas adjacent to the weld metal. This is because, owing to the softening of the HAZ, these areas become the weakest part of the weldment. Unless relatively ductile weld metal is used and severe restraints are avoided, cracking can occur easily in these areas (avoid high restraint).

One way to avoid the softening of the HAZ is to weld the alloy in its solutionized (solution-annealed) condition first and then postweld-age the entire weldment to develop high strength. Unless this procedure is carried out properly, postweld heat-treatment cracking can occur.

I hope this helps you somewhat...

MC PROFUSION
Toronto, Ontario, Canada
Website:

http://www.mcprofusion.com

 

[TVP]

You can find a great deal of information on welding nickel-based alloys by visiting the websites of producers like Special Metals, Haynes, etc.:

http://www.specialmetals.com/publication/Joining.pdf

http://www.specialmetals.com/products/publication/tech_bulletin_718.pdf

http://www.specialmetals.com/products/publication/tech_bulletin_a-286.pdf

http://www.haynesintl.com/CRAfab/CRAweld.htm#Gen

http://www.haynesintl.com/pdf/h2031.pdf

 

[cmarinelli]

MC Profusion and TVP,

Thanks a lot for the information. I already have some of the Special Metals info, but not all.

Is AMS-STD-2219 (now AWS D17.1) the defacto standard in aerospace fusion welding?

Thanks Again,
Chris