Stainless Steel for Fireplace

[jakgop21]

Hello forum members, my cousin wants to put stainless steel in his fireplace as a backing material .

He is using 20 gauge stainless don't know of the grade. So he asked me if i would try welding some test pieces. I have a miller 135 mig welder. i got the tri mix gas and stainless wire from the weld shop and tried it out.

Learned very quickly about the difficulty. First of all they are trying to reduce if not get rid of the what i would call the weld penetration coloration on the other side. i like it because it adds art to the weld but apparently they don't .

question 1 : Is it possible to do this without the coloring on the other side of the weld?

question 2: Any recommendations for any clamps to hold the pieces together at a 90 degree angle to weld it? Or do i have to catalog order one from the weld shop.

question 3: Any tips for mig welding this ? Or is this better left for a tig machine ?

question 4: How will the stainless handle the heat of the fireplace? Will it warp and lose color?

i ran a test bead wasnt pretty but held together. Then i ran a few tack welds but didnt hold up to bending since it was only tack welds. Ive heard people do multiple tacks or run half a bead, wait and then resume to avoid distortion?

What do you forum members do?

I would appreciate any help and advice

Thanks

 

[kkroger]

Stainless warps if you look at it funny.... Heating Stainless is going to color it... Best you can probably do is Light Straw color. Material is most likely 304 Stainless. TIG is your friend, MIG will Sugar.

 

[JimDon]

With all due respect:
That "coloration" you are seeing and trying to eliminate is the HAZ of the weld. That translates to the Heat Affected Zone. In basic welding, that is the FIRST thing you look at to see if your weld has enough penetration to actually cause that coloration. No coloration = not a good weld. Period. Do not try to avoid causing that coloration because what you put together without it will likely fail. I would tell your relative to find a different welder to do what he wants and see what response he gets.

My feeling is that you may not be up to (I sincerely mean no disrespect.) the technical skills for the task at hand.

Welding for a fireplace, in my book, would be akin to welding up a trailer to go on the public highways. If your skills aren't up to the level required, you could be putting yourself and others in peril. Consequently, don't do it.

Cheers,
JimDon

 

[bon3s]

A few things from someone that welds stainless every day...

Color:
- First off we dont ever try to avoid it,... we want it we like it... tells us what we need to know about penetration and strength, then we clean it. Wirebrushes and scotchbrite pads are your friend.

- Secondly... 20ga in a fireplace and they dont want to see the color... news flash, use the fireplace a few times... guess what, its gonna change colors, and depending on what it is your building and how its anchored/secured, gonna warp all over the place.

Mig/Tig:
- If your asking what to use, your most likely (no disrespect) out of your depth. I know and understand this board is all to jup to TIG TIG TIG, but if i were building this and wanted it to stay close to the shape i was aiming for, id MIG it all day long if i was able to (meaning where the welds are placed - we do food grade, so we cant MIG alot of things).

- If you think MIG with a small 110v machine on 20ga is hard, tig is gonna make you pull your hair out and then put you in a straight jacket if your not someone that TIG's on thin stuff daily.

Clamps:
- Here is where your in a bit a luck, and its 2 fold: Easiest way to hold them pesky 90's with clamps... toss some angle in to clamp that thin stuff to, this also allows you to use that same piece of angle as a backer/heat sink thus keeping you from burning through as well as reducing the sugaring ect. Not fool proof but will allow for a slightly larger margin of error. Alumn. angle works wonders, but any will help.



Aside from all of this.. small hot tacks often when doing assembly. Dont be afraid to weld this will a fast moving downhill MIG with no weave with .023 wire.

Set up and practice what ever position your going to weld this in, and try a few... the one your most comfortable with might not be the one with the best outcome.

Best of luck, thats all I got unless you post of some pics or more detail on whats your shooting for.

 

[why worry]

I have welded a lot of 20ga SS it can be very unforgiving. JimDon is correct about the discoloration equaling penetration and as such it is your friend. Now as to how to get rid of it you can grind it off with a fine grit in a stripe pattern. This is referred to as "stripping" when finishing SS. One issue with welding the SS for a fireplace is the what you don't warp welding it is going to warp and discolor from the heat of the fireplace. I built a cone fireplace out of SS quite a few years ago and the heat marks are actually quite nice from the hot areas.

 

[no704]

I would clamp the parts to be welded to an al or cu block and
Weld the back side. But 20ga SS is not going to be happy in a fire box.