solid inserts in tubing

[coley13]

this is not for aluminium sorry but i figure seen this section see's the most topics about fabrication.

question, with my lower frame cradle tubing is it a good idea to put some solid inserts inside the tubing and set it up for a butt weld? would tubular inserts be better option?

with the solid inserts would that create stress on the hollow tubing and create local buckling and or cracking?

whats peoples ides's on this, i realise people use billet on some of their AF builds.

i've had a bit of a set back, ordered my 4130 crmo tubing at $27 meter and took it into the local engineering shop to get it bent to shape and the bloke never used a mandrel bender and stuffed my tubing by creasing it so i've got to order some more now and start again.

[100hp honda]

seems most guys are using 6061. was it not available in your area ?

[cryzsurfer]

Actually that's what I did on my AF project. I had mine water jet out and mitered to fit snug as the original frame tube I.D. had slightly different dimensions. When I fit the whole thing up I left ~ .100" of the insert showing making it a sort of backing bar or chill ring resulting in 100% penetration in all of my butt welds. On Chrome Moly I don't think this is as needed as the thickness of the tube and weld characteristics as very different. I would just make sure the area is free from paint and oxides, purge it with argon and preheat it. You can also wrap it after welding to allow it to slow cool and reduce stresses. Use ER80S or higher filler and it should do fine. Make sure also that there's a vent hole somewhere for allowing the excess pressure from blowing out and allowing the argon to flow freely.
Craigus