Chromoly to carbon - filler?

MosquitoMoto · Mon Nov 30, 2015 6:33 am

Okay, after putting together some small projects of my own, I'm now confident I can TIG well enough to join a frame loop onto a friend's custom motorcycle project for him.

The loop is chromoly, the main frame is steel. Everything will be carefully coped for a close fit, fastidiously cleaned then welded.

I've seen Jody using ER70S2 for welding moly but I've also seen him using ER309SS for joining differential metals. Any thoughts on the preferred filler for this job?

Cheers,

Kym

motox · Mon Nov 30, 2015 7:05 am

Kym
i have welded plenty of 4041 frame parts and always use
ER70-S2. a note: fit up should look water tight.
voids are not good..
craig

MosquitoMoto · Mon Nov 30, 2015 7:33 am

motox wrote:Kym
i have welded plenty of 4041 frame parts and always use
ER70-S2. a note: fit up should look water tight.
voids are not good..
craig

Craig -

Thanks for that. I have been working quite a lot lately with ER70-S2 on carbon steel and have been getting to know it fairly well. And yes, I'll get the fit up perfect. I've learned my lessons in the recent past with hurried coping and a weld that becomes an ugly compensation job as a result...

Cheers,

Kym

Oscar · Mon Nov 30, 2015 8:39 pm

ER309SS is great for joining dis-similar steels when one of them is already stainless. But for 4130 chromoly it's a no-no. Same goes for 312SS. I read it in one of the 50 web-links I read, and I remember it making sense at the time, but can't remember which link it is. I have it saved somewhere though.

ER70S-2
or
ER80S-D2

Other super-alloys might work as well, but completely un-necessary.