TIG welding 8620 chain

[andrewjmorin]

We have acquired a process that uses a dedicated TIG welding unit to butt(?)-weld 8620 steel chain links. We are experiencing early failure. Can anyone here school me on what a capable process for making good connecting links would look like?

 

[TVP]

If the grade is SAE 8620, then welding problems will likely occur frequently. Have the links already been heat treated? Quenched and tempered? Carburized? Either is a problem, with the latter a serious one.

 

[metengr]

Most chain link welding that I have seen in the industry is done using the electric resistance process, not GTAW.

The chain industry has standards, you can Google this information.

 

[andrewjmorin]

Thanks for the quick responses!

This was my fear: that TIG was a bad call made by the folks from whom we bought this process. I know exactly jack about welding, I usually leave welding-spec calls to my fabricators, but in this case it's an in-house process that creates custom chain assemblies by linking several shorter 'stock' units.

I'll need to do some more digging to answer TVP's ???s.

-andy

 

[andrewjmorin]

This just in:

The links are purchased as cold-rolled wire bent into a 'C' shape, mechanically closed and manually TIG welded with filler-metal as recommended by the welding outfitter. They are getting 'porosity,' and failures at the proof-load. The chain (which determines the proof load: ~25,000 lbs iirc) is high-grade 1/2" chain of standard dimension, the links are of 5/8" diameter wire.

 

[unclesyd]

If you can use a mechanical link there are several types available at this site.
Here is a site that 2 types, a Lok-A Loy and a missing link type, in two different grades.

http://www.slingchoker.com/sling2/crosby/chain.htm