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Up Topic Welding Industry / Technical Discussions / TIG VS. MIG
- - By jaycole Date 01-15-2003 13:06
As a major cost reduction, my company wants to eliminate as much TIG welding of our 304 SS as possible, and go to MIG welding. We already MIG mild steel and some SS, robitically mostly, but the point of testing was brought up. The director of engineering was asked, and he's of the opinion that TIG welding is superior in strength and over time (Vibration Testing specifically) will last longer than MIG welding. His opinions are shaped by experience, but is there a technical foundation for these opinions, or did he just test some bad MIG welds in the past. I've asked around a bunch, and I'm maintaining that, "If done properly" neither is superior for strength. I'm I right? Are there other issues to be considered?
Parent - - By DGXL (***) Date 01-15-2003 17:41
I agree with the "if it is done correctly" philosophy. Either process will produce satisfactory results.

GTAW obviously provides better control with regards to heat input (if performed properly).

GMAW obviously permits higher deposition rates and travel speed (if performed properly). This also permits a reduction in heat input.

These are just a few factoids. There are many more reasons to utilize one process over another.

Have you guys tried any of the GMAW composite SS electrodes?
I recommended the use of this type of electrode to a client 7 years ago who was hard-core TIG when it came to welding SS. His thoughts have changed since switching to a composite GMAW electrode. The product they were fabricating from thin gauge stainless sheet (304L by the way) had less distortion and the production rate for the numerous short fillet welds required more than tripled.

Parent - - By jaycole Date 01-15-2003 19:44
When MIG welding SS, we're using ER308LSi, and I don't believe any variations have been tried recently. What does a composite SS electrode consist of? Can you give me an example number?

Thank you for the input.

Parent - - By DGXL (***) Date 01-15-2003 20:18
A composite electrode is a metal cored electrode, not flux cored.

An example of a steel electrode classification would be ER70C-6M (C denotes composit or metal cored). This is becoming very popular electrode for GMAW fabricators.

An example of a SS electrode classification would be EC316L.

Give em' a try. Most who switch hit between solid and cored wire find the higher deposition rates and minimal spatter advantageous.

Ask your welding distributer for samples. Most of these people are happy to offer sample spools or reels. Tell them your specific application or go directly to the electrode manufacturer, they enjoy helping out has always been my experience. ESAB, Lincoln, Tri-Mark, and the other specialty electrode producers like Select-Arc or Bohler-Thyssen have these as well if I remember correctly. Give them a call.

p.s. They are not cheap electrodes, but you will make up the cost on the back end as the client I noted previously found out. Clean-up was minimal and production...

Parent - By jwright650 (*****) Date 01-15-2003 21:05
I went to a seminar at a welding supply house and they were pushing the metal cored wires. I heard from other attendees that they were really happy with switching because of what you just stated. Fume generation was considerably less and they enjoyed being able to see the other end of their shop again.
Good points,
John Wright
Parent - By Niekie3 (***) Date 01-15-2003 18:28
Theoretically, I will agree that "done properly", both processes will give good results. Practically however my experience has shown that the chances of picking up Lack Of Fusion (LOF) when welding GMAW-SS transfer is quite high. This will definately reduce the fatigue properties of the welds.

In addition, GMAW tends to lend itself much better to abuse than is the case with GTAW. (Typically welding with deposition rates that are too high is a problem. This can lead to grain growth which affects impact properties.)

At the end of the day, you need to select the process based on what is best for the particular job. When full penetration welds from one side is required, GTAW is the more reliable way to go. If higher deposition rates are required, then GMAW will be favoured. It's a matter of "horses for courses".

Hope this helps

Niekie Jooste
Up Topic Welding Industry / Technical Discussions / TIG VS. MIG

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