Welding Tips and Tricks

I'm currently practicing on a purge fixture for a stainless test, and having some trouble on the top size.

Not sure if I am going too slow, but when I start to go faster I don't get full penetration.

Settings:

• 16ga 304L stainless
• .045 308L filler
• 45 Amps
• 3/32 2% Lanth
• 17 Torch Gas Lens
• #8 Cup 15 CFH
• Purge 10 CFH.

I was kind of thinking its a shielding issue on the top side, otherwise I'm likely cooking it. My gas lens tends to come loose, and I am not sure why, but when I replace my tungsten it loosens I guess.

Kinda thinking that may be the issue otherwise I'm going too slow?
I feel like I am going fast enough due to the nice straw color on the backside?

Thanks!

What power source are you using? Does it have pulse capability?

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A sycrowave 250 without the pulse functionality, or a multimatic 220 ac/dc with pulse.

I can also add, the purge fixture has no chill on the top side. It is just two steel plates with a gap that the argon comes through, no diffuser material, and the coupons sit on top.

If I could put some AL blocks on top I would, but I don't have any that sit without falling off or lifting up one side ruining the purge. Trying to make due with what I've got, its essentially a 16ga butt weld, no backing, no chill.

You're just barely getting any purge, you need to get better gas coverage on the back side for sure.

Can you put up a pic of the purge fixture?

I'm not at the shop but here's a 3D render of what it looks like.

https://a360.co/2v9M7p0

I think your fixture should be ok. If you can't clamp the pieces down with bars you should tape them down to stop air ingress if the pieces warp while welding.
Assuming the fit up is tight, no gaps, the solution is therefore a combination of heat input and speed of deposition.
Try the pulser power source with these settings:
2.5 pps
50% on time
50% background current
63amps on the peddle.

Tacks should be on each end and every 2".
Light up on the end tack, when it puddles get going, the speed of travel should be just slow enough to achieve full penetration. Experiment with this. Keep your filler in your left hand near the arc in case you get a key hole open up, you need to speed up if this happens. 1/16" material can be autogenous, no filler reqd if the fit up is tight.
You will also benefit from a number 12 cup if you have one.

Show us your progress please.

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Fit up is tight. Coupons are sheared, fitup with shear side down butt joint.

I tack about .5 inches from the ends and 1 in the middle. I do get warping while I am going along, however I figured that was mainly due to no chill, I suppose clamping could help, I just need to figure how to get the clamps on there better.

I am using filler, I wash the puddle down the joint and dap into the leading edge of the puddle to bring it back up to size and repeat.

I have a number 10 alumina cup, but the results were the same afaik.

With sheet metal you need alot more tacks to prevent separation from warping. Excessive reinforcement beads on thin sheet metal is pointless and only results in overheating of the joint and warping.

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so typically the fixture would have an exit for the gas on the opposite end of the inlet, but when the plates warp then your not able to maintain the purge.

If you saw the recent video of the purge fixture Jody got from Abom79, the hold down clamps is what your missing, otherwise it should work.

To make this weld you need a tight arc, consistent travel speed, torch angle and filler addition. Without a good back purge it'll be even harder.

I would also recommend using a clean file to clean up the sheared edge, contamination in the sheared edge could also be causing you problems. Ideally I would cleanup the edge on a mill to ensure a flat edge that won't have any gaps when you butt them together.

Is this for a weld test that will get x-ray? If so what code are you welding to?

I welded this many years ago using a fixture like Jody has, material is stainless.

LtBadd wrote:Is this for a weld test that will get x-ray? If so what code are you welding to?

Just a visual as far as I know. No code in particular. Working toward some sort of AWS certs (not very familiar with the TIG certs), the CWI is pushing me toward sanitary stainless and aerospace.

It's pretty open ended, I am not a professional, just trying to set a goal of getting to a certain level for my own enjoyment.

That looks awesome! I'll shoot for something similar when I keep practicing. Maybe I'll try to fab up my own purge fixture (with clamp bars) for practice.

bap_

Post back with some pics, comments, or questions if we can help

Just got back from giving it another go. I was having the same issues even with clamping. I took more pictures to provide some more insight into what I am doing. Today I kinda played around with a few different things.

1. No Gap (Same as before) I cooked it IMO. Couldn't get full pen without cooking. Not all of them were horrible but color was a little gray.
2. No Gap Pulse (1pps 65 amps) I cooked it IMO. ditto
3. Slight gap -- Best results so far.

I used aluminum coupons on top of the stainless to clamp. The fixture is tricky to clamp on since the stainless coupons are cut to maximize each sheet.

Is that really a purge fixture? We haven't really seen it in a pic by itself. If it's just a flat piece of steel plate it's a bad mix and you need to get your work piece off it and onto some aluminium or copper, clamp it down and try again.

I posted a 3d render. Looking back should have taken a photo of it without it all fixtured up hah. There is certainly a trough and that black hose is flowing argon at 10cfh.

It is made of mild steel so ya its not going to be as good as AL.

Found it. I usually don't bother with link clicking, there's been plenty of posts in the past from gunna's trying to show off their 3D draughting skills then claiming they're gunna build this and gunna build that but you never see the end product.

In your case you did build it, kudos. I don't think mild steel will make much difference in a short work piece such as yours. Nice tight fitup, plenty of tacks, no reason not to achieve a good result. Why don't you try the pulse settings I gave you. Hold the arc still till you get a puddle going the step a little with each pulse slow enough the puddle follows you but fast enough to avoid keyholing. The sweet spot travel speed will be when you do this and get the penetration you desire. You can tell when you are penetrating by observing a pin hole in the puddle. If have enough argon cover top and bottom, you will also get the good colour and little warping.

I will try your pulse settings on monday.

Try the pulser power source with these settings:
2.5 pps
50% on time
50% background current
63amps on the peddle.

The millermatic 220 does not have background current control or on time control, but I'd bet its close to 50/50. I was almost at your settings this week but at 1 pps instead of 2.5, I'll give that a go. Do you recommend no filler or dip filler during on time?

I need to play with no filler as well with both pulse and without pulse, and see the results and how the puddle goes.

You can tell when you are penetrating by observing a pin hole in the puddle.

I need to continue to play with it. That is good info though, I normally just kinda notice the puddle start to sink just a little. I'll keep an eye out.

The settings I gave you I use for 16 gauge, tried and proven and autogenous with good fit up. It's a good idea to keep 1/16" filler in your hand ready to dab in case you goof and open up a key hole, if you dab quick you can save it other wise you have to stop and cuss. You can back off on the peddle too if things are getting too hot.

In the above photo's you have 2 that show the back side, for whatever reason you're still not getting a good purge. This will affect the weld, there should be very little discoloration.

Where ever the argon is escaping, you should be able to wet your finger and feel the gas flow, if you can't then it's one of 2 problems,

Either you have too little gas flow or the area that the gas can escape is too large for the amount of purge flow.

You want a balance of inflow to what can escape so that there is slight pressure inside the fixture, too much pressure and it'll push up on the weld.