[Greg From K/W]

I am tig welding stainless and haven't had much problem.

I should give some details about what it is I am doing. Our company does Elevator control systems. I am welding the surface plates. I weld up the corners of the panels. After that they are ground up and the panels are sanded to give a finish that can repel finger prints. Its the brushed stainless look you get.

What is going on is after I weld them up they are ground down to form a nice rounded corner. I am finding that after they are ground that there are small cracks in the metal. There is some crystallization on the back of the welds. When the welds are sanded to final finish I find the cracks. I try as I might to reweld these areas yet they keep coming back.

They used to send these out to be welded. I have seen the ones that have come back and there is no problem with the chrystals on the back of the weld at all. I am told I am using the exact machine he is using. I am going to try upping the heat a little at a time to see if that helps me out. 90% of my welds are fantastic. Is it possible the grinding may be causing a problem?

Any input you folks have would of great help to me in my career with this company.

Thanks for the help. Greg.

[weldin mike 27]

Hi there,

There are lots of products to help shield the back of stainless steel welds. There is a gel type stuff that you put on the back of the joint and it turns into a slag with the heat of the weld.(Good for odd shapes and tight spots) If you can get abit of copper in there to support the argon from the tig torch that could help. You can make your own purge chamber to whatever shape you need with some cardboard and masking tape. The crystals on the back of the weld will be hard and shitty, when you grind of the good weld metal on the outside, you expose the contaminated root of the weld and could be why its is cracking, maybe? Jody has done a few videos on purging. Check em out, might help.

Hope this helps,

Mick.

[Greg From K/W]

Ok I have viewed a few of them. I will check out some more. Also the gel do you just smear some on the back? I think that is what is going on. Its 16 gauge metal and I am welding it at 49 amps. I would throw it up a little more but I am hesitant to raise it up much more. Perhaps by 5 would maybe help me out. I will look at some more videos.

I suspect that the chrystal is being exposed after the grinding. We shall see. Thanks for the help.

[Tireman9]

Can you post a picture of what the weld looks like from back side after you weld but before they polish?

[weldin mike 27]

Hey there,

I think that is the go with the gel. However make sure you have the weld root protection stuff.(I am not sure of the names exactly) You don't want to go sticking your finger in Passivation gel. That crap is nasty acid. A welding or stainless steel supplier should be able to give you the exact info.

Good luck
Mick

[Otto Nobedder]

If you can't purge the back of the weld, then "Solar Flux" is the product you're looking for. It comes as a powder you mix with denatured alcohol to apply to the back of the weld. If the back of the weld is exposed to oxygen, then all the exposed backside becomes metal oxides. When the corner is ground smooth, you are left with very little metal that is not a brittle oxide. The flux basically melts into glass that seals out air and prevents oxidation.

Steve

[Greg From K/W]

Ok I will look into that stuff. I will get some pics of them before the grinding takes place. No problem there. Purging isn't possible to do but I think that the paste will help out. I run my tank at 25 so I think that should be lots of argon for what I am doing.

[Greg From K/W]

Here is the weld I have done. Out side corner stainless steel. Notice that the weld is grey looking and that there is a dark brown or black substance on each side. I turned up the balance on the welder to about half way. It seamed to go better. I tried to turn it down 5 amps and I kept loosing the weld. I turned it up 5 amps and I kept burning hold. SO I put it back at 49 amps.

I can get that flux from the welding supplier it will be about $69 for one pound.

What does a piece of copper do on the back of a weld? I have brass plates I might be able to set up behind the welds. But what does it do to effect the welds? OR what effect does it have?

[Greg From K/W]

Ok forget the question about the copper DUH I found it. Someone slap me.

[weldin mike 27]

Hi,

Have you got the machine on A/C? You said you adjusted the balance. Stainless steel is usually welded DC- so the balance does not apply (forgive me if i read it wrong). Glad to see that you are asking lots of questions and learning from the answers. A pound of that stuff should last a while, might be the best money spent Good luck.

Mick

[Greg From K/W]

I will check that out. I wasn't sure 100% about that. Thanks for the info though. What about the colour of the welds? Is that a concern? I thought they should look cleaner than they do. What would cause that grey look?

[Greg From K/W]

I am using DC power so you where right. The copper trick worked out really well. The backs of the welds are just as nice as the tops are now. Thanks for that tip guys.

Oh ya special thank you to Jody for all the videos and I got my tig fingers today. Ordered 3 of them. Can't wait to try them out tomorrow. I am going to look really professional with all this information. Thank you so much for all the help everyone. I really appreciate it.

[Greg From K/W]

Really wish the guy I am working with would stop grinding through the sheet metal on the corners after I do such a nice job welding them up now. Its a real pain to fill them in when the metal disappears under your torch. Most times I am able to fill them in but what a PITA.