Welding Tips and Tricks

Ive resently tried to Tig weld stainless 3 inch 0.060 pipe.
Out of curiosity i tried a magnet on it. It turned out to be ever so slight magnetic.
the coulr of the weld is blue and goldish.
the only thing I did not do is back purge. I`m waiting on a dual flow guage.
Any ideas or is it just the back purge?

Im curious, what grade of stainless is the pipe and the filler?

The pipe is supposed to be 300 series like a 304 or 308. the filler im using is 308.
Ive heard that heat will change the charactoristic.
But this time I have less heat and a better colour. The picture does not show it well, but its not burnt.

Stainless that has been cold-worked in any way becomes magnetic. This is a test I use on 304N vessels where there appears to be buckling. If the buckled area is magnetic (sometimes very strongly!), I know the area is flexing regularly. Welds on austenitic stainless are also magnetic. Cold-formed mandrel bends are also magnetic.

Nature of the beast, and nothing to do with back-purge.

Steve S

Okay Steve,that explains alot. So if it slightly magnetic then its not in jepardy of rusting then I guess.

Danylo66 wrote:Okay Steve,that explains alot. So if it slightly magnetic then its not in jepardy of rusting then I guess.

Yeah, no worries. 400 series stainless, like many kitchen knives are made from, will hang from a magnetic holder and never rust.

Steve S

Here is a pic of 2 pieces of flat strip 304 welded into an angle and polished, with 2 neodymium magnets securely attached to them. As Steve pointed out, I believe the welds have caused the SS to become magnetic. They won't attract to any other SS I have that is in a natural state. Stainless is fascinating metal.

exnailpounder wrote:

20170330_151829.jpg

Here is a pic of 2 pieces of flat strip 304 welded into an angle and polished, with 2 neodymium magnets securely attached to them. As Steve pointed out, I believe the welds have caused the SS to become magnetic. They won't attract to any other SS I have that is in a natural state. Stainless is fascinating metal.

Even so, would you say that since welding it has become "slightly" magnetic, or....?

LtBadd wrote:

exnailpounder wrote:

20170330_151829.jpg

Here is a pic of 2 pieces of flat strip 304 welded into an angle and polished, with 2 neodymium magnets securely attached to them. As Steve pointed out, I believe the welds have caused the SS to become magnetic. They won't attract to any other SS I have that is in a natural state. Stainless is fascinating metal.

Even so, would you say that since welding it has become "slightly" magnetic, or....?

Richard, it definitely has. Depending on the strength of the magnet, you can always feel a little "tug" from stainless but since being welded this little demo piece is truly magnetic...nothing like MS...you get one of these little neodymiums stuck on a piece of steel and they are incredibly hard to get off. I was wondering if the polishing might have contributed anything to it too.

exnailpounder wrote:... I was wondering if the polishing might have contributed anything to it too.

That's an interesting question. One wouldn't think so, but it's an easy enough experiment. Test a piece of scrap sheet for magnetism, then polish it thoroughly and test again. I don't have the equipment for polishing metal (though I claim to polish turds as part of my duties at work), so if anyone tries this, please report.

Steve S

Otto Nobedder wrote:

exnailpounder wrote:... I was wondering if the polishing might have contributed anything to it too.

That's an interesting question. One wouldn't think so, but it's an easy enough experiment. Test a piece of scrap sheet for magnetism, then polish it thoroughly and test again. I don't have the equipment for polishing metal (though I claim to polish turds as part of my duties at work), so if anyone tries this, please report.

Steve S

I'm thinking that maybe polishing won't make it any more magnetic, but because you'd have more surface contact area it would have a stronger bond, creating the feeling of being "more magnetic"

Just a thought...

Otto Nobedder wrote:

exnailpounder wrote:... I was wondering if the polishing might have contributed anything to it too.

That's an interesting question. One wouldn't think so, but it's an easy enough experiment. Test a piece of scrap sheet for magnetism, then polish it thoroughly and test again. I don't have the equipment for polishing metal (though I claim to polish turds as part of my duties at work), so if anyone tries this, please report.

Steve S

You've polished a few turds around here

LtBadd wrote:

Otto Nobedder wrote:

exnailpounder wrote:... I was wondering if the polishing might have contributed anything to it too.

That's an interesting question. One wouldn't think so, but it's an easy enough experiment. Test a piece of scrap sheet for magnetism, then polish it thoroughly and test again. I don't have the equipment for polishing metal (though I claim to polish turds as part of my duties at work), so if anyone tries this, please report.

Steve S

I'm thinking that maybe polishing won't make it any more magnetic, but because you'd have more surface contact area it would have a stronger bond, creating the feeling of being "more magnetic"

Just a thought...

I'll polish up a piece and see what happens later but right now I have a bonfire and a gallon of screwdrivers all mixed up and I am about to defile myself so you'll have to excuse me

exnailpounder wrote:... I have a bonfire and a gallon of screwdrivers all mixed up and I am about to defile myself so you'll have to excuse me

I'll have to give you my dirt-simple recipe for frozen screwdrivers before the summer hits. Delicious, and you don't know you're getting intoxicated until it's too late.

Steve S

Otto Nobedder wrote:

exnailpounder wrote:... I have a bonfire and a gallon of screwdrivers all mixed up and I am about to defile myself so you'll have to excuse me

I'll have to give you my dirt-simple recipe for frozen screwdrivers before the summer hits. Delicious, and you don't know you're getting intoxicated until it's too late.

Steve S

Oh I know I am getting intoxicated because I start out with that intention If I feel it's taking to long I usually get the whisky out and I wake up in the yard with a million mosquito bites and wet pants PM me that recipe...maybe I can make it for the wife and get lucky before the end of summer

See Jeff it's all your fault

Either way... I'm curious about this polishing thing. Metal does weird stuff I know so anything is possible-especially with stainless it seems.

I have a few parts that I wire wheeled. Only the weld is magnetic. The rest of the surfaces are not magnetic. i will try to duplicate the parts and not wire wheel them. I think id like to duplicate that frozen screwdiver recipie as well


Danylo

Danylo,,

Here's the recipe, verbatim to what I sent Jeff....

A standard blender base/blade will perfectly fit a quart small-mouth mason jar, including the kind with the mug handle...

In a quart mason jar, place 6 OZ frozen orange juice concentrate (use a good one). Pack the remaining space with ice cubes. Fill the voids left between cubes with room-temperature to slightly warm (good) vodka. This will average about 6 OZ. This will melt just enough ice to screw on the blender base. Make Sherbet!

Best drank through a large straw, like an Icee.

You can also add a shot or two of peach schnapps before the vodka, for a frozen "Hairy Navel"

A college friend described her first experience with this (she drank three before she knew it was hitting her) as Snot-slingin'--floor-crawlin'--gravel-eatin'--toilet-huggin' drunk.

Danylo66 wrote:I have a few parts that I wire wheeled. Only the weld is magnetic. The rest of the surfaces are not magnetic. i will try to duplicate the parts and not wire wheel them. I think id like to duplicate that frozen screwdiver recipie as well


Danylo

Polishing sometimes heats the metal up to an uncomfortable level to hold so it might add something to it because afterall, we're heating up metal by welding it and that's what causes SS to become magnetic......stay tuned

Farmwelding wrote:See Jeff it's all your fault

Either way... I'm curious about this polishing thing. Metal does weird stuff I know so anything is possible-especially with stainless it seems.

It's always my fault...I'm married so I'm conditioned that way. It's like Pavlov's dogs...instead of coming for food when the bell rings...when the shit goes down, I just automatically assume blame.

My report. The strips of SS I have (pictured) are absolutely magnetic so didn't even bother to polish one to see if it added magnetic attraction. I have a brand new sheet of 1/8"304 SS plate that I just picked up for a job that is not magnetic whatsoever and the magnets do not stick to my 304 SS beer keg casting furnace that has been heated to over 1500 degrees inside and the outside gets way too hot to touch on the outside. I tried the shroud on my burner that is 304 and gets cherry red when I use it and it's not magnetic at all so apparently heating SS doesn't induce magnetic attraction...so why does welding?. I thought because these little magnets are so strong that they were able to stick to the very slight magnetism that SS has but they do not. I sent in this pic because if you read the print on the strips( ya gotta stand on your head...sorry) it clearly states it is 304l and is magnetic. What alloy of SS is this? I don't have any other SS to polish at the moment but when I cut up the SS plate for my job coming up, I'll polish a piece and see what happens.

I think the bar is magnetic because of it being roll formed. Welding ss causing it to become magnetic I believe happens because of the electricity from the process realigning the molecules in a parallel direction. The heating it up beyond a certain temp ( not sure exactly what temp) with flame allows them to randomly realign, relieving stress and magnetism. You could confirm this by welding ss with oxy/ acetylene.

Poland308 wrote:I think the bar is magnetic because of it being roll formed. Welding ss causing it to become magnetic I believe happens because of the electricity from the process realigning the molecules in a parallel direction. The heating it up beyond a certain temp ( not sure exactly what temp) with flame allows them to randomly realign, relieving stress and magnetism. You could confirm this by welding ss with oxy/ acetylene.

You could be right about the cold forming but is strip cold formed? I thought SS came in a natural non-magnetic state because the manufacturer doesn't know what application the metal will be used in and magnetic metal can spell trouble in some applications. Interestingly enough...the welds on my beer kegs are NOT magnetic and beer kegs are pressed into shape and welded around the circumference...so they should be magnetic right? I'm scratching my head right now.

We need a metallurgist fromiliar with the manufacturing proscess in the forum.

I'll pose the question on the Welding and Materials forum on linkedin. There are several metallurgists there.

As for the beer kegs, perhaps the welds are not done electrically, or the metal is normalized after welding?

Steve S