[namijo]

I am new to welding, no prior experience. I am taking a TIG class at the local college. I have been doing well so far, but need some help with this next joint. I just started welding stainless and I am just not getting it. One of my required welds is a horizontal butt (groove, no gap) weld with 1/8" stainless. Every attempt has one of two outcomes: penetration through the joint but got too hot, or looks good with good color but not full penetration. I am using 1/16" tungsten and filler. How would you run this? I can, but don't have to, use pulse. I can back the pieces with other material as long as the groove joint is open, not backed by anything.

[tweake]

hopefully someone will answer as stainless tends to kick my but a fair bit.
what are you using to purge the back side?
i'm not sure what you mean by "penetration through the joint but got too hot,". that sounds like not enough amps and going to slow. i also suspect you will need to cram the rod in rather fast or go up a size in filler which helps cool the puddle.

[cj737]

Stainless is extremely heat sensitive.And the backside of a butt joint needs a backer or a purge, else it will sugar. I would bump up to 3/32 filler also.

When the puddle gets hot, adding filler cools the puddle, with 1/8" material, 1/16" filler may not be sufficient to cool your puddle enough if you aren't experienced enough to taper your amps. If you do use a back and a gap, then 3/32" will definitely help fill and cool your puddle.

Personally, I like to use pulse whenever possible on stainless. A quick hot blast gets your puddle, and the background reduction chills the puddle rather quickly. You could probably stick with 1/16 under pulse, no gap. Aluminum flat stock clamped to the back helps chill and prevent and fusion to the sheets.

I'd be running around 90 amps for 1/8" material.

[namijo]

Personally, I like to use pulse whenever possible on stainless. A quick hot blast gets your puddle, and the background reduction chills the puddle rather quickly. You could probably stick with 1/16 under pulse, no gap. Aluminum flat stock clamped to the back helps chill and prevent and fusion to the sheets.

I'd be running around 90 amps for 1/8" material.

Thank you for the quick response. I am going into the lab today, all day if necessary. I am determined to get this done.

Pulse, use the "rule of 33" settings for the pulse?

Running at 90 Amps with pulse, would you expect to be run nearly full pedal and fast?

[cj737]

I don’t use “33”, I prefer about 50% on time, 25% background, and a slow pulse 1.5pps. With pulse, you might be slightly higher 100-105, full pedal. Gotta experiment for your style and experience level.

[Poland308]

If your base metal is 1/8 then that’s about equal to sch 10 SS pipe. I’d be at about 80 amps and use 3/32 wire. No pulse, but a reastat would be nice so you can back off the amps as the piece heats up. SS is a bear to first learn if your shooting for full penetration. It will test your skills at reading the puddle. Your looking for what’s often called the devils eye. It will show up in the puddle at the focus point of your arc. You see it just before everything blows through or falls out. When you see it it’s time to travel. It’s kinda like balancing a spinning egg on a needle.

[namijo]

Thanks for the encouragement and advice. I used your tips to try different things to see what worked for me. First, I decided to pass over the 2G for right now and jumped to a 2F Lap Joint. I played with the current, pulse settings, travel speed, etc. I ran 90A, 60% on time, 40% background, spot checked my setup to ensure good argon coverage. I was able to achieve a passing lap weld, and repeat it consistently, with these settings. Thanks again. Now I am on to the 2F tee, and then return to the 2G.

[noddybrian]

That's looking good - really solid progress congrats - I feel that a joint with a corner is easier to follow & traps the shielding gas - I find that open corners / flat grooves are harder as my eyesight is very poor & I don't have much vision in my right eye - it was a good call to try a different joint & return to the one your struggling with later - when you do maybe you can clamp a straight edge to follow near the groove to help with both gas cover & keeping steady if that's permitted.

[cj737]

That looks a lot better! But you are still a bit hot on that joint. Try running it again with your amps turned down 5 amps. Notice at the end of your weld the "blue"? That's heat.

If you are using a pedal, as you approach the end of a weld you need to begin tapering off the pedal to avoid the accumulated heat in the base material from cooking your weld. Stainless is very sensitive to this. It is very difficult to make long, continuous welds on stainless for this very reason. Your goal is a silvery, light straw colored weld. That is the perfect amount of heat.

You can experiment with your pulse settings (lower peak, definitely lower background) and see if you get to even better results. Remember, the background amps is a % rating of your peak. You are running 54 amps in the background. If you drop to say 33% or 25%, you are then running well below your peak and that eliminates the heat soaking with stainless as you move.