Welding stainless and low carbon steel

[DPittman]

I'm going to be welding a stainless steel baffle to ordinary steel in a wood stove. Am I better off using SS mig wire or regular mig wire?

 

[whydontu]

my understanding is you should use wire that matches the higher-alloy material. That way you don’t compromise the characteristics of the stainless baffle

 

[phaxtris]

309 filler is the "correct" filler for that, but in reality for a baffle in a wood stove i would use what ever is in the machine at the time, chances are its going to crack in time anyways being that stainless has a much higher thermal expansion rate than steel

 

[DPittman]

Thanks for the replies. Ya I suspected it would not make a huge difference given the application but I wondered if one would be a bit better. I think I will go with the SS wire. The weld is just to hold the the baffle plate to the top inside of the wood stove and will only be 5" long.

 

[Former Member]

SS wire.

My understanding SS wire even for cast iron.

 

[Aliva]

I've used 309 in the past with good results

 

[Ian Moss]

For a weld that will not have a lot of stress other than from thermal, I would use several short stitch welds rather than one continuous weld.

 

[DPittman]

Now I'm worried my plan is going to cause stress cracks in short time.

I'm wanting to weld the outside perimeter of a 1" OD SS pipe into a matching hole in regular 10 gauge steel. The SS pipe is a secondary air combustion intake that will be on the back of a wood stove. The wood stove is for my hunting/camping tent and so does not see alot of use, but of course it has extreme temperature variations. The pipe weld will be the only fixed portion of the entire assembly and the pipe will move with the expansion of the stove wall. The weld will have to be continuous and air tight

 

[phaxtris]

Now I'm worried my plan is going to cause stress cracks in short time.

I'm wanting to weld the outside perimeter of a 1" OD SS pipe into a matching hole in regular 10 gauge steel. The SS pipe is a secondary air combustion intake that will be on the back of a wood stove. The wood stove is for my hunting/camping tent and so does not see alot of use, but of course it has extreme temperature variations. The pipe weld will be the only fixed portion of the entire assembly and the pipe will move with the expansion of the stove wall. The weld will have to be continuous and air tightView attachment 22570

just repair it when it cracks, which who can say when it will with infrequent use, its still going to take a lot of cycles before it even starts

if you were to use it while camping with a small crack in it the risk of carbon monoxide poisoning is pretty much nill, tents leak air live a sive, and it would be a small leak.....if thats a concern

in a perfect world you would swage that connection together, but that requires some specialty gear

 

[Darren]

I weld SS exhaust tubing fairly regularly as part of my job, using regular er70s mig wire. Never a problem in 25 years or so. I wouldn't do it for structural, but for exhaust work its been fine.

 

[YYCHM]

Flanges with asbestos washers to seal the through hole(s), no welding involved?

 

[DPittman]

I weld SS exhaust tubing fairly regularly as part of my job, using regular er70s mig wire. Never a problem in 25 years or so. I wouldn't do it for structural, but for exhaust work its been fine.

Good to know thanks.

But if you are welding ss tubing regularly, why wouldn't you use a ss mig wire? Cost? Convenience?

 

[DPittman]

Flanges with asbestos washers to seal the through hole(s), no welding involved?

Hey we think alike! I was initially going to do that but threading the pipe and making washers to fit seemed like too much.

 

[YYCHM]

Hey we think alike! I was initially going to do that but threading the pipe and making washers to fit seemed like too much.

Does it have to be SS? I'm thinking most of it could be had at PA pre-threaded (gas fittings maybe?). As to where to get asbestos sheet for washers I haven't a clue.

 

[Darren]

Good to know thanks.

But if you are welding ss tubing regularly, why wouldn't you use a ss mig wire? Cost? Convenience?

I was working in shops. They would just say "so and so can weld it with the wire we have, why can't you? Just do it! " so I did, and it was not an issue. Not necessarily the way I would do it at home, but I did it. And it worked.

 

[DPittman]

Does it have to be SS? I'm thinking most of it could be had at PA pre-threaded (gas, water pipe maybe?). As to where to get asbestos sheet for washers I haven't a clue.

Well it probably doesn't have to be ss but I had the perfect ss pipe anyhow. SS handles the high temperature better. (Ever seen a SS BBQ burner vs plain steel burner?)

The real (commercially made) wood stoves always seem to have the baffle plate and air injection tubes made out of SS. So I'm doing that too.

If I keep adding accessories and steel to this stove it won't be going camping/hunting without a front end loader to carry it to spot.

 

[Darren]

To add a bit to my previous story about how you do what you're told....

Back in 94 i was working as an asphalt plant operator/millwright/welder type of thing....before i decided to do something with my life...anyways...

it was the end of the year right before winter shut down. Late December...We had a couple burnouts working midnight shift at the sand washing plant. We had a big order from the airport for washed sand (no fines, specific granular size) that had to be delivered before winter shut down. The guys left sometime in the middle of the night because they didn't have a loader operator to load the plant for some reason. Instead of calling someone, they shut all the water pumps off and left, which you never do in winter.... When our crew came in at 6am, it was -25c and getting colder. Every cast iron part cracked. elbows, tee's, a few pump housings, and some pipes. We replaced a few parts, but 4" piping is not common around here so nothing was available, it was a mad panic to weld up the cracks and get everything going again for a few more days of production. No pre heat, no nickle rods, all 7018, just in an effort to sorta glue the cracks shut and get enough water from the frozen over ponds to the plant to run a few more shifts. It was horrible...but after 12 hours of welding for 3 guys, the job got done. Sometimes you just gotta do what needs to be done , especially if your paycheck depends on it.

 

[Aliva]

You can use silver solder

 

[DPittman]

You can use silver solder

I don't think silver solder would work in this situation as silver solder needs tighter fitting joints and the situation also needs some build up to aid in structural integrity of the joint. But your right, silver solder can be used to join two dissimilar metals. Thank you.