Need advice on welding thicker metals

strantor

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I am a welding novice. I have been welding for years, but I don't do enough welding to maintain proficiency or gather a wide pool of experience. My main welder is an Eastwood TIG200, AC/DC 200A TIG/Stick machine. I also have an old craftsman MIG (125A? I believe) that's pretty much useless for anything outside of sheet metal. I opted for TIG as my main machine because I wanted the cheapest (larger/more capable) machine I could get, that I could also use to weld aluminum. I have done lots of smaller jobs with it and have been happy with it so far.

I had my first experience last week doing a larger job on thicker steel with the TIG, and I am not at all happy with how it went. I made some modifications to a friend's trailer, probably a total of 25 linear feet of weld on 3/16" and 1/4" steel, and it took over 12 hours. The welder has a rated 60% duty cycle, but I empirically discovered that the WP17 torch (or, maybe my hand) has its own duty cycle which is significantly less than that. After 1-2 minutes of welding at anything over 150A, the torch gets too hot to hold with a gloved hand, and takes 10 minutes sitting in front of a shop fan to cool down. Probably only an hour or two of the 12hr job was spent actually welding.

I did a bit of research and I'm still researching, but I thought I would post here for help in addition. One thing that I came across on someone else's post on another forum, was a suggestion to upgrade to an 18 series torch. I don't know much about parts interchangeability with these torches. I went to the Eastwood website looking for a bigger torch, or a water cooled torch, and they do sell some stuff, but they only advertise it as being compatible with their bigger machines. Will any welder that uses a 17 torch, also use an 18 torch? And what is meant by "series?" Is there a specific 18 torch I need? What about a water cooled torch? What would fit my machine?

One thing I did find on the Eastwood website that they guarantee fit, is the stick holder torch for this machine. The specs that Eastwood provides seem only to apply to the TIG process. Very little is said about its stick capabilities. Will stick welding give me better results on a project like I just did? Also as far as stick goes, I would like to know if I can weld even thicker materials with stick, than what the machine is rated for on TIG. I have a project coming up where I will need to weld 1/2" steel, possibly even 3/4"; I am pretty sure I know the answer for that - I'm going to need a bigger welder. But I thought I would ask just in case.

Thank You
 
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A 200 amp machine with a 60% duty cycle used in stick mode should have allowed you to finish in a couple of hours max. Get yourself some stick rods and practice some. I think you will be pleasantly surprised.
 
a) water cooled torch for Tig
b) the job sounds like a Mig/stick job in actuality
I am about to order the stick holder lead for it. I would also like to order a water cooled torch. Do you know specifically what type/series/model/whatever of water cooled torch will work for a machine that was designed for wp17 torch? And is there some other equipment required to go with it?
 
When I think of TIG I always think that TIG is best for precision work. Welding a trailer doesn't fall into precision work. To weld a trailer, I'd definitely use a stick welder. And for 1/4" you'd easily get by with 125-150 amps stick welding.
 
On thicker material...grind a V groove so the rod can flow into the metal on both sides I used to move the in a small sweeping motion as I moved it sideways. I have not wilded a lot of thick stuff on a wirefeed. I used to have a stick welder. Loved to weld and see the flux curl up and have that pretty weld. Also the smoke from the rod really worked good with hangovers the day after...lol
 
You have to get the water out first..............(LULZ)



Preheat


I wouldn't have thought that preheat would be required for this although it certainly wouldn't cause any harm.

Preheat is important in steels with a higher carbon content or other highly alloyed steels to slow the cooling of the weld pool in an effort to reduce the hardness of the weld / Heat Affected Zone (HAZ). It does become more critical as the thickness increases but 1/4" steel isn't that thick in the grand scheme of things.

As for water, water is a source of Hydrogen in the weld pool. In thicker sections or in alloys that are prone to cracking Hydrogen can build up in the weld metal until enough pressure is present to crack the weld and / or the HAZ. Again, I can’t imagine that this would be a problem in ¼” (presumably) mild steel however if the grade is unknown then preheating could be a good idea. 95°C is often recommended as a minimum for C-Mn steels although as the carbon equivalent creeps up you may need to go higher (i.e. chromoly steels).

Hydrogen cracking can be particularly hazardous because the cracks don’t always appear immediately and a weld that has passed inspection can suddenly fail in service. Because of this it is worth checking your welds again after 72 hours if the material you are welding is known to be susceptible.
 
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