Tri Mix on mild steel?

[cornf3d@yahoo.c]

J here

I have to do a stainless project, thus I will be using Tri-Mix. The problem is the project is not that big.

I wanted to know: Can I use Tri-Mix for mild steel welding?

Advice please. I am going to be building a sorting rack for the orchard. I plane on making the rack out of 1/8 inch angle, I will be using a HH140, .30 wire and tip, anything else I need to consider welding stainless?

I will be using stainless filler wire too.

I think I want to go with 316L, we get up to 180 inches of rain a year here in Hawaii.

Thanks

Jeremy

[weldgault]

I would not use Tri-mix for Steel, because of the Helium. JG

[yorkiepap]

Hey Jeremy,
You would get your best results with a mix of 80/20(AR/CO2) or 85/15 since you will be doing short-circuit welding. There is no need to get into any tri-mix. Here's a site that has 99.5% of answers you may need in the future. I use it & make note of the extensive data available & the information has never failed me. Hope this helps....

Denny

http://www.weldreality.com/short_circuit_under100.htm

[SundownIII]

yorkiepap,

Have to disagree with using the C20/C15 mix for welding stainless.

The reason he'd doing the project in SS to begin with is because of it's resistance to rust. Not using tri-mix will result in beads which "WILL RUST".

Just this past summer, I had to repair the bridge railings on an imported trawler which had been welded (previous repair) with mig. Stainless wire and the wrong covering gas. May just as well have used steel wire. Overall, to sum it up politely, it made a freaking mess. Cost him twice as much as if he'd brought it to me in the first place.

Tri mix is not recommended for welding mild steel.

[yorkiepap]

Hey SundownIII,
Yup, you are correct. I looked at the wrong column in my notebook. I should have posted 95/5 or 98/2. My mistake..... I stand corrected. Thanks.... Denny

[metarinka]

Hey SundownIII,
Yup, you are correct. I looked at the wrong column in my notebook. I should have posted 95/5 or 98/2. My mistake..... I stand corrected. Thanks.... Denny

just to further clarify

CO2 by code is limited to I believe under 4 or 5% for stainless steels especially if the Low carbon stainless steels are used such as 304L or 316L

if co2 in great concentrations are used you run a very good risk of increased chances of carbide precipitation which could make the area rust around the weld.

All that being said you don't HAVE to use tri-mix for stainless steel. 98/2 with 2% CO2 works very passibly especially if it's a one off project because you could use that for carbon steels as well. There is also 98/2 with 2% oxygen as that improves bead fluidity and makes the welding a little less sluggish, but i don't like to use it as it increases the potential for oxidation issues. Also and while you could use tri-mix for steel it would be a waste, and in fact for most applications I think it's a waste for stainless as well.

at the last facility I worked at I transferred carbon steels MIG welding to 85/15 and all stainless steel to 98/2 (CO2) and it worked out just fine for us.

[TRG-42]

First off there are numerous "tri mixes" so you cannot say you shouldn't use tri mix for carbons steel

First off the reason you use a helium based tri mix 90He7.5Ar2.5CO2 for SHORT ARC welding of austenitic stainless is since short arc is a relatively low heat input process, you need the increased arc energy of the He component ( higher ionization potential and also has much better conduction of heat ) but cannot rely on CO2 as you can with carbon steel

Every gas supplier in the universe specifies this blend for short arc austenitic stainless because it is the BEST choice end of story

This is why the Stainless spray gas of 98Ar202 is not a good choice for short arc

This is especiallly important for you because you have a small welder

Conversely you do not generally use a He based tri mix for spray / pulse welding of austenitic stainless because the arc voltage is much higher ( due to the higher ionization potential of He ) The exception to this is newer pulse power supplies such as the Lincoln Power Waves that have special pulse waveforms that spray the He tri mix suprisingly well

Filler Metal - you want to be using a Type 308 ( the 316 will be of no advantage )

If I were you I would go to a .035 flux cored stainless ( ask for a E308LT1-1/-4 ) at your local store. The reason for this is these electrode run with 75Ar25Co2. You will have a cow when you see how much a tank for 90He7.5Ar2.5CO2. At least you can use the 75/25 for all your

Using Tri Mix for Mild Steel

The Tri Mix for mild steel are all proprietary blends. Example - Praxair Helistar CS is has 28He 60 Ar balance CO2, Linde Argoshield Pro is 20He, 68Ar balance CO2 etc

All these tri mixes offer good good benifits over traditional blends

The tri mix 90H7.5Ar2.5CO2 is NOT a good choice for the simple reason it's not cost effective, and the arc voltage required for proper spray / pulse is unreasonably high

The only time you generally see high helium mixes for short arc carbon steel is for low alloy ( CrMo etc ) welding since higher the CO2 content the alloy recovery diminishes

Having said that, you can use the 90He for the short arc carbon steel just to use it up if you want.

[SundownIII]

TRG,

I didn't get into a detailed discussion of the different gases for spray on purpose. The OP clearly stated he planned to use a HH140 which eliminates any discussion of spray transfer.

Here in VA, a 330 of tri-mix (for SS) only costs me about $20 more than a bottle of C25. It's not gold.

On the other hand, have you priced flux cored stainless lately. That is, if you can even get it in a spool size that will fit in a HH140.

You provided a lot of good information, but not a whole lot that was relative to the question asked by the OP.

[B_C]

Wow I am worn out after reading this far and still don't know what is the best way to get Stainless Mig welded......I think I'll have a Sandwich since it's 1:57 am and I can't sleep....:D