Solder for hot or cold rolled steel?

No experience, but it would seem to me that epoxy would be what you are looking for. i.e JB Weld or the like. Doug

OH-KAY, so . . . I've found references to silver soldering and brazing. Some pretty good references actually. Doesn't look all THAT easy for fair quantities. At least, doesn't look all that safe for long term exposure, considering typically there's cadmium in the solder mix and so lots of ventilation would be necessary. Also there's the problem of hazardous materials disposal for a business. Anybody have any better or more complete information than what's available at the following link?

Dozens of them. Look at silver solders. Work beautifully if you clean it nicely before hand, then pop it in an oven.
You might even look up bike frame manufacture, and the old days of "lugged" frames. Nice low-tech, low-skill process (low skill compared to bronze welding). Solder costs a bit and the old ones are full of cadmium, but them's the lumps.

For good info on silver brazing try : Your example is not too clear. The joint looks Ok but how deep is it? You certainly have more than enough surface area on contact. Randy

Furnace braze.
Sporkman wrote:

As far as I can see from this drawing, your joint does not look overly challenging - basically an end filler for a "clapboard" like sheet. If the parts have decent fitup, it's simply a crooked line with a 90 degree outside corner joint - or else the drawing is not giving the right idea. A 90 degree outside corner is not particularly hard, and a 90 degree outside corner with little zigs and zags is not particularly hard, either. A human or a clever robot should have no trouble welding that, or else you need to explain something about the drawing that the drawing does not convey.
JMHO, etc...

Seems like skip welding then sealing with something, like epoxy as previously mentioned would work. Welds need not be continuous..

Looks like the joint where aluminum siding meets the outside corner on a home. Need some real pictures or mechanical drawings saved in JPEG format for better viewing. If it was a home you would us chalk to seal, lol.
What is the thickness of material? Is that a butt joint?

MANY THANKS for all the good posts. In answer to Randy Zimmerman's question and following up on Lawrence Smith's observations -- yes, the joint is not deep. It's just the thickness of a formed steel sheet . . . probably would use #16AWG (about .06). But considering the length of the joints and the number to be made (on a pretty continuous basis, as I explained) I still doubt very much that welding is a good option. Very, very labor intensive and tedious for the welder to be doing that all day long. Robots are not likely to be a viable solution because of the volume (medium, at best) and the probable variations on the theme (the joint can be longer or shorter, the formed sheets may be of several varieties). But the joint could indeed be made such that it would wick pretty well, so brazing is quite possible, and I've found solders without cadmium so my concerns about toxic materials is considerably less now. I'm investigating the possiblity of induction heating to braze, but the parts won't lend themselves well at all to being surrounded by a coil. We'll see what an induction heating manufacturer has to say about it. Jeff Finlayson's idea about tack welding followed by epoxy is a good possiblity.
I'd like to ask Andy Dingley what he means by "lugged" frame bike frame manufacturing. I've looked at some Google results, but it's no clearer to me.
Best regards to all who replied, Mark 'Sporky' Stapleton Watermark Design, LLC

Yes, that's a butt joint, and the material thickness is around 1/16" (probably will use #16AWG, which is a very small tad less than .06").
Lance wrote:

The sort of frame that you very rarely see these days, except for people doing tiny-volume handbuilds.
A "lug" is a complicated multi-tubular fastener for joining bike tubes. There's one at each corner and you buy them ready made. Then you cut the tubes to length, insert them into the lugs and silver solder the joins. For production manufacture ('70s or earlier) these would all be done together in a furnace. Take a look at some older bikes - where the frame tubes appear to have a "sleeve" at their ends, that's a lug.
Modern frames are made by butting the tubes against each other, then welding or bronze-welding the joint. It's much harder to do, because you need to jig the angles while you're welding it.
I've an old late-'40s frame of my Dad's, made by a very famous frame maker. The lugs are hand-filed into gothic shapes, and have the initials of the maker and the customer sawn into them.

Dear Sporkman:
Just a add a tiny bit here: Think of PVC pipe into PVC pipe tees.
It is a shame you cannot make your "washboard" as a single stamping, including the upturned rib (hydroforming). Volumes probably do not support this in the large. What about establishing a "mer" of one or two corrugations (plus an overlap joint), including the upturned rib, and seam them together with spot welds to establish the necessary length?
David A. Smith

Thanks very much, Bob K, Andy and David. I'm clearer on lug type design now. Unfortunately it doesn't look useful for the application. I'm very intriqued by David Smith's suggestion and hope he can explain a little more. I DO actually figure that the washboard shape would be best made via forming/stamping and I'd consider it worthwhile to have the tooling made. In fact, it's probably the only reasonable way to consider it. But I was having a hard time understanding how the "upturned rib" could possibly be formed out of the same piece of sheet metal, at least until I looked up "hydroforming". Never had heard of that before. Looks very interesting and I'll investigate it further. If I understand correctly what you're referring to as the upturned rib is the structure on the left of the JPEG -- what you're actually seeing is the "bottom" of a U-shaped sheet metal channel. The channel has a purpose, so I don't think hydroforming is applicable in this case, but I'm glad you mentioned that process. It's thought-provoking in the least. But did I understand you correctly, or were you bespeaking a different idea when you say "the upturned rib"? And I've also never seen the term "mer" before.
By the way, I'm thinking now more in terms of putting tabs on the edge washboard shaped sheet and inserting into slots in the left hand member (the sheet metal channel). Insert tab A into slot B (and weld). Would probably work out best if we do the slots in the channel via a hard tool, even at the volumes we're talking about. And since I haven't found off-the-shelf channel that's narrow enough anyway (1" from front to rear) we're probably looking at getting that custom made regardless, so a little extra tooling cost could go a long way toward simplifying fabrication.
Thanks for your time and interest, 'Sporky'

Dear Sporkman:
You got it correctly. The piece you are bonding to the main corrugated part, could be formed from the same sheet. Or at least enough of it that simple spot welding can provide the bonding to a more "formal" channel.
Think chemistry. Poly-mer. Many mers, or units of similar construction.
Good luck!
David A. Smith