TIG welding Stainless Lap joint  1/4" 304L

I found a few pieces of laser cut 1/4" thick 304L stainless in one of my scrap buckets so I am using it for a lap joint video.

Stainless steel requires less amperage than carbon steels so even for 1/4" thickness, I only used 95-105 amps.

In fact, I was plugged in to a 115volt circuit for this video.

TIG welding stainless lap joint


What is the best TIG cup for Stainless Steels?


Different cups are needed for different applications but overall, I really like the Jazzy 10 ceramic cup.

To me, it seems like a big improvement over even a #8 gas lens cup.

The additional diffusers provide for much better argon shielding with about the same argon flow rate as the #8 uses. (around 20-25cfh)

I used a #7 clear cup for filming on the root pass because clear cups tend to light everything up better and can make for a more instructional video.

The first pass seemed to need around 105 amps to get penetration into the root.

Sometimes 1/4" thick stainless requires a full 1/4" fillet weld size so I decided to make a second pass.

I switched over the the ceramic jazzy10 cup for the second pass at around 95 amps.

Best Practices for TIG welding Stainless Steels

  • use a dedicated stainless steel wire brush that has not been used on carbon steel
  • use dedicated abrasives that have only been used on stainless steel
  • establish the weld puddle quickly and get moving within 2 seconds ...thats 2 seconds from the time you light up until you are moving the puddle
  • for full penetration welds like on stainless sanitary tubing, a purge is necessary. A dual flowmeter makes purging easy while using only one argon cylinder
  • For multiple pass welds, let cool between passes to avoid carbide precipitation. Read a detailed article on carbide precipitation here

pictured below is the SPARC dual flowmeter, you can see it on my store here

sparc dual flowmeter in box

A dual flowmeter makes purging possible with only one argon cylinder.
But did you know another use is running 2 welders off one cylinder?

tig kits banner 1

What is Carbide Precipitation?

Carbide Precipitation in stainless steels occurs when the metal stays too hot for too long.

Carbide precipitation can lead to something called stress corrosion cracking so it pays to take measures to avoid it.

See the full article on carbide precipitation here where I explain it in simple terms.

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