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Welding stainless steel questions.

Started by Firewoodjoe, March 28, 2015, 09:07:54 PM

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magicmikey

   The boiler rusts because there is free oxygen in the water, to remove it entirely requires chemical treatment. It is restored in an OWB each time the boiler temperature goes down and the water shrinks pulling in air from the vent.
   A pressurized boiler does better but as the oxygen level decreases the water becomes more aggressive in restoring the balance. The pex tubing for hydronic heat has an oxygen barrier for this reason.
   In an all steel boiler the rusting will be mostly uniform over the entire surface. With ss and a smaller area of steel the same amount of rusting is concentrated in one area.
mike
   

Firewoodjoe

Ok I got it home. And a clear up on the rod I was told to use. It's 308 not 508. But anyhow I'll try getting some pics up. Id guess it's about 1/8 thick. And the chimney and the door assembly is welded to the firebox of which both of those are standard steel. So it already has stainless welded to carbon steel.

Firewoodjoe


Firewoodjoe

 
The first photo I was trying to get the small cracks. If you look really really close to the middle right of that bead you can see a crack. They are all over. The second just shows how big the area is. I'll try to get a better one of the crack.

Firewoodjoe

  Should be better view of a few cracks.

Bill Gaiche

309 is a good rod to use for mild steel to SS. bg

Corley5

What caused that to crack ???  Was it ran dry?
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sandsawmill14

we used to put up ss vent hoods in commercial kitchens, code required all welded 10 gauge black steel vent pipe. I always welded them with flux core wire welder. we weld truck axles with stainless rods and when we had to build special grease traps I used 1/8 ss and stainless rod and welded 2" galv steel pipe fitting to the end for pipe connections. I have never welded ss with ss rod unless it had to be polished for looks. I use the ss rods to weld cast iron more than anything else. I keep ss rods on hand but only use the when i have to. They cost to much  >:( last ones were almost $4 each :o
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shamusturbo

Depending on your welding skills, you want either and inlay patch (cutting out bad and replacing it flush) or an overlay patch (welding a patch over the cracks and seam welding shut). An overlay is obviously much, much easier. I would stick with SS/308 wire. It is a little harder to weld but the "dissimilar" metal will cause a certain level of water contamination/rust/build up. what have you.

MIG welding it would be the easiest option, if you have access to one. TIG would be the best option but requires the most skill, by far. And stick would work and is probably the most readily available. If you don't know what base metal composition you have (you may have more than one grade of SS- 304,308, 310, 347 etc) you want to weld it with the higher of the two grades.

If, when you weld the new patch in and it starts to crack, you want to let it cool down quite a bit. Having a "temp stick" from the supply store helps. Let it drop to 200 degrees before you begin to weld again. If it does crack again, drill a 1/2" or bigger at the end of every weld you intend to make and weld toward the hole and lastly close the hole. Don't maintain too much heat.

I hope this helps. I have been welding all my life. I am a certified weld inspector by day and firewood junky by night. I can't get enough of either.......
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shamusturbo

Also:
Practice on a scrap piece of SS. Making circular motions slowly. 3 seconds per dime swirl.....sounds crazy.
Take a magnet and make sure you are welding SS. It should not stick at all.
Opening the crack will allow more room for the metal to expand after it loses the heat from welding.
(Same idea with the drilled hole at each end of the crack- allows for expansion.
The weld teacher said to weld with 508 because there is no way to verify the grade without a $20k "PMI" gun.
508 would most certainly be an "upgrade" from 308, thus covering anything lower than 508.
If it's mass produced, I can almost guarantee its 304. Most affordable and abundant.
A pad weld may not hurt either. AKA Base metal build up.

Good Luck and Keep us Posted!
Stihls 660,461,460,390,200T
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Gators- TS Loaded
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Firewoodjoe

Well thank you guys. Corley yes it was ran dry. It all started with the chimney having a hole started mid way through the water jacket. He ran it and his auto fill must not have worked. Then all this started. It will deff. be welded with a arc/stick welder. That's what I have and know. I welded up my old stove many time so water tight is no problem. Just never welded stainless. I'm thinking I'm going to cut the patch area out (use that for practice) then weld in new. If I can get stainless from the local supply at a resonance price I will. And yes 5 rods was $17 dollars😳

LeeB

'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

Firewoodjoe


LeeB

Just wondering. A torch don't cut so good in stainless.
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

nk14zp

To cut it you can use some damp 6011 rods with your welder turned up all the way on ac.
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Firewoodjoe

What makes it so diffferant? It starts as carbon steel right?

LeeB

Won't burn. Just turns red. I suppose it's the same thing that keeps it from rusting. No oxidation, no cut.
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

Don_Papenburg

Use your plasma cutter.



Or the neighbors
Frick saw mill  '58   820 John Deere power. Diamond T trucks

LeeB

You have much better off neighbors than I do.  :D
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

sandhills

When we put in the milking parlor I mentioned earlier, it was bought used and all the stansions were cut out using a plain old 7 1/4" circular saw using worn down blades from a 14" metal chop saw.  Not saying this is OSHA approved but it did the job just fine  ;D.  Might be a little wider kerf than what you're planning though?

Firewoodjoe

My question of what makes it differant wasn't towards cutting or it rusting but how do they make it differant? I mean it's old fashion  steel under that shine someplace right!

Don_Papenburg

I belive it is an alloy throughout because the side of the cut will be the same .  Not a laminate.   The alloy is rolled out in sheets and extruded into shapes.   Stainless alloys consist mainly of chrome nickel and carbon and other elements.
Frick saw mill  '58   820 John Deere power. Diamond T trucks

Firewoodjoe

Well after talking to some local metal workers and friends I think I'm going to replace the entire fire box.  Looking up stainless steel properties and it's good for heat but under long high heat it will get fatigued and crack. I'm not going to mess with that in the middle of winter! I'll keep you all posts when some action starts. Thank you all for your input.

InterMechanico

http://www.azom.com/article.aspx?ArticleID=1175

This table will help you to choose the correct grade of stainless for the rebuild. I'd go with 309 as it's probably more widely available than 310.

Happy Fabbing!

Julian
Approaching every job with a mind for completing it :)

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Qweaver

Quote from: Firewoodjoe on April 01, 2015, 08:32:48 PM
What makes it so diffferant? It starts as carbon steel right?
304 & 308 SS are 18/8s   18% chrome and 8% nickle  thus the high price and corrosion resistance.  Chrome has a high affinity for carbon and will cause intergranular  corrosion and subsequent failure in the weld zone when welding carbon steel to SS or using regular carbon steel electrodes.
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