Welding question

Can regular steels be structurally welded to Titanium. specifically 4130 to 3al-2.5v

 

No.

 

Bonding titanium to stainless steels has been achieved by diffusion, interlaying technique and epoxy ahdesives. But why would you weld 4130 to titanium for a structural part? Such a structural part might suffer from thermal differences and there are barely a couple of uses that would justify such an idea.

I guess for such questions Boku's answer would be a more appropriate one.

 

The word structural was only chosen to convey the need that a proper weld was achievable, apparently not so question answered, making the why a moot point.

Thanks for the replies.
Ken

 

To expand on my earlier comment:

The key point here is the word "structurally." From what I've read on the internet, such joinings can be achieved. However, I don't think that there are any such that the interface reacts loads that get anywhere near the yield stress of either material, or for which the allowable stresses are consistent and predictable. To my way of thinking, that means that it can't be done in a way that you can trust in an aeronautic structure, so it is not structural.

 

Guess I'll have to look elsewhere to save a few pounds, a diet is out of the question :gig:

 

Probably yes, at least titanium can be welded to some stainless steel grades. Search the internet and there are scientific papers on friction, stir friction, explosive and laser beam welding of titanium to stainless steel. It look like it is done to manufacture equipment for the nuclear power industry.

Still the question lingers, why?

 

It seems to be a rather exoctic welding not just simple tig.

Chuckle chuckle,
It's not the heat tollerance, it's not the corrision resistance, so what's left?

Or do you mean where am wanting to use it?

 

It is also used in aerospace, rocket and missile industry/technology, but such metal composites are way beyond what an average homebuilder could handle. Besides building a supersonic aircraft/rocket, I am really curious why would one need it.

Logically, yes.

 

I think logically (some times to a fault) and the questions was "why" not "where"

There is what amounts to about 8 foot of 1" x .058 4130 tubing for the throttle and collective system, each has horns that are to be welded to the specific sections of tubing. I've already machined the horns from 4130, the whole titanium thing was an after thought with the couple pound weight savings being what I was after and will forgo since the two metals are not particularly weld compatible and not wanting to re-machine the horns from titanium.

 

What are you building that needs 8 foot of steel tube for a collective..?????.

 

Rivets

 

HAHA, yes it will take just short of 8 feet, 21" each on each throttle tube that rotates over the collective tube as well as several other tubes associated with the collective, 8' is real close in total, not one single tube.

 

Actually thats not a bad idea, just no clearance to the inner tube.

 

If you haven't totally given up yet, what about an interference fit with a rosebud type weld ? Heat the 4130, and chill the titanium end and slip it in place. Then drill 3 small holes 120 degrees apart minutely piercing into the titanium maybe 2 inches from the end of the tubing. Make a rosebud weld in each of the holes. Even if it doesn't bond the metals, the internal irregularity would prevent the end from moving even if the interference fit loosened.

 

ekimneirbo
Thanks for the help, love how you guys think differently for solutions.

Unfortunately, what you are suggesting (as I am visualizing what you are saying) is not possible as the tubes with the horns rotate in close tolerance around an inner tube and are only 1/8" thick.

I wish I had the complete setup modeled to show, not far from it though.

 

Stainless steel will weld to 4130. Because they are both steel.

 

Unfortunately, that would offers no benefit in weight savings which was my hope, in fact SS is ever so slightly heavier.

Thanks for the input BBerson

 

Oops, I misread post #8 and thought you wanted corrosion resistance. Carry on. Can't help.

 

Did you consider the option of building a carbon fiber torque tube? It could save even more weight.