Welding Techniques

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What is Welding?

Different types of welding. Transcript (Click here)

In this video we're going to be talking about different types of welding:

  • TIG Welding (GTAW) 
  • MIG Welding (GMAW)
  • Dual Shield Flux Core Weding (FCAW-G)
  • Stick Welding (SMAW)

TIG Welding (GTAW) 

You got to have the metal cleaner with TIG welding than with other types of welding, at least it's more fun that way. 

[Demonstration using Cabon Steel, DCEN, aka straight polarity].
Once you've got the metal prepped correctly, a nice tight arc where the arc length is equal to or less than the electrode diameter. Don't use too much torch angle and keep the hot tip of that rod shielded with argon gas and things will go pretty good for you.

[Demonstration using 304L Stainless, is typically welded using ER308L filler]
One of the main things to consider when you're tig welding stainless steel is maintaining the stainless properties. And the way you do that is you don't use any other wire brushes
other than stainless steel wire brushes that have only been used on stainless steel.
And you limit your heat input and chill bars can help an awful lot with discoloration, as well as distortion.
Here I'm using some aluminum angle chill bars on a little stainless steel manifold. And
it's about an eighth of an inch thick and on carbon steel I would probably use about 125 amps. Stainless requires only about two-thirds the amperage that carbon steel does.

I’m using a foot pedal. Sometimes a foot pedal is used, sometimes a foot pedal is not used in TIG welding. I prefer to use one whenever I can. 
Same things apply for TIG welding stainless steel: holding a nice tight arc, having good gas shielding, keeping that hot tip of the filler wire shielded with argon, and chill bars help a lot. All you need to do to switch over to aluminum is just change the polarity to alternating current (AC) and change filler wire and you're off to the races. That's what makes TIG welding so versatile and so popular for welding all kinds of alloys.

Same things apply, you probably hold a little bit longer arc on aluminum than you will on stainless steel, but don't get carried away, don't get crazy, a good tight arc length will go a long way.
TIG welding is also an excellent way to weld pipe.
[Root pass, 1/8 gap, 95 Amps, 1/8 inch ER309].
Here I am welding a stainless flange to carbon pipe using 309 filler, using a technique where I move the arc forward and back, not side to side at all, but just strictly forward and back. 
[Stainless steel roots should be shielded with purge gas].
The inside is purged out with argon and that's the result. I like to walk the cup on pipe welding as much as anybody does, but sometimes it's better to freehand. And when you have to freehand that does give you the ability to move forward and back and side to side a little bit more than walking the cup.

But for a for a uniform weld, walking the cup is hard to beat. And if you're in welding school I suggest you take the time and pick the instructor's brain and get all the instruction and all the practice you can because it is a highly paid skill to be able to walk the cup on pipe.
Wire brushing a stainless steel weld while it's still kind of hot, but not too awfully hot, lets the oxides come off there pretty easily.

TIG Brazing is using silicon bronze or some other aluminum bronze or something like that and where you're not really melting the base metal but you're just melting the filler metal. I find that about two pulses a second with about twenty or thirty percent background does a great job. For TIG Brazing it really helps to have an oversized cup.

MIG Welding (GMAW)

MIG welding aka Gas Metal Arc Welding (GMAW). 

Next up we're talking about MIG welding, mostly short circuit MIG welding for
this video. That's a really useful process for light duty fabrication. The settings on the inside of most MIG welders are pretty good. They're a little hot for anything except for flat, horizontal, and overhead, but I'm going to use those recommended settings right now for two different t-joints. 
The first one I’ll use a slight push angle, I’ll let it cool off all the way and then for the other side I will use a pull angle. Then we'll cut an etch and we'll look at the difference in penetration. I've done this about a hundred times. I see so much discussion on which one's better, which one's proper which one's right, which one's wrong, on forums and good thing is that they both can work. That's a good thing because sometimes you absolutely have to do one or the other. And if you hold a tight stick out, you use a decent angle, don't get carried away with the angle and you got your settings hot enough, both of them will work. 
And you will find out in just a minute here when I do a cross-section here and do a cut polish and etch that you're just not the difference (in night and day) like some people would have you to believe. 
Okay which ones pull which ones push? Slight differences a little bit more crowned up on the pull, but the penetration is there on both of them.

[Chart showing 240 volt for ¼ inch (V.WFS) is 20.9/456].
Now again, those settings recommended for quarter inch are super hot. If you try to weld uphill with that with short circuit MIG, unless you're way better than I am, you're going to have a problem like this [shows uneven welded join that dripped].
It's just so hot going uphill it just wants to run out with you. So, what I do is just pick a setting, about one or two metal thicknesses lower (still using the chart), but then also
using a little technique, like this little triangle technique which:

  • steps me forward and still keeps the arc on the leading edge of the puddle, 
  • keeps me burning into the root of the joint, 
  • helps the metal spread out a little bit, 
  • gives me a little pattern for some uniformity, 
  • and makes a decent looking vertical uphill weld, instead of one that falls out on my boots.

Short circuit MIG is very useful for fabrication. It's not used much in heavy fabrication or out in the field in fabrication, at least it shouldn't be necessarily it's used a lot of places
where it shouldn't be, but for light fabrication like this on eighth inch wall square tubing welded to some tread plate making a platform it's ideal:

  • you're not going to burn through the eighth inch,
  • it's really quick, there's no cleanup,
  • it's really easy to make tack welds, 
  • there's no slag.

You just have to recognize the limitations, and for eight inch wall square tubing to eighth inch or three sixteenths tread plate, there just aren't many limitations: you can weld uphill, you can weld downhill, side to side, it really does a good job on about eight inch thick. 
3/16ths is about the limit where I would then start going uphill, but that all depends on a lot of things.
[3G test plage downhill root, uphill fill cap].
Short circuit MIG isn't used a whole lot, once again for heavy structural welding, but there are some plate tests given out there; especially, just kind of entry level tests to work you into pipe.

Once again your settings are going to be a good bit lower than the recommended settings on the inside of the MIG welder here. In this case for this cover pass I’m only using 17.7 volts 200 inches a minute (ipm) with o35er 70s6 wire. These same settings for this plate will work just fine on the same thickness pipe as long as the bevel is the same, the gap is the same, and the land is the same. 

But basically, you're just kind of scooting across the middle, not spending a lot of time and pausing briefly on the edges and overlapping the edges of the bevel by only about a sixteenth of an inch. And then trying to progress evenly up the joint and if you progress evenly and your timing is kind of even you're going to have a uniform cover pass. Stick out is important, gun angle is important, and don't get carried away with either: hold
a pretty short stick out with a slight push angle things should go okay.
This particular test joint the root pass was done downhill and the subsequent passes were all done uphill, but that just depends on the procedure. Neither one is right or wrong, tests are given both ways: if the test calls for uphill route you weld to uphill route, if it calls for downhill route you weld the downhill route. This is the same type scenario on the same thickness, same bevel, same gap and everything on pipe: downhill root uphill fill and cap.

Whatever settings worked on that plate will work just fine on this pipe. In fact, you might not even notice the difference here - I’m using the same exact technique trying to overlap those bevels by just about a sixteenth of an inch and get almost the same result. Do a little quick cut and edge here, just to make sure there's no lack of fusion. You might hear me talk about cut and edge a lot; it's a great way to prove out a procedure.

Dual Shield Flux Core (FCAW-G)

Dual shield flux core is an awesome process! You can go uphill, and you can go uphill really hot with hardly any torch manipulation and still get a good sound uniform bead. Very little manipulation right here, just almost none, and still comes out flat, uniform, not overly convex, and you just can't do that with short circuit MIG.
Dual shield flux core also burns through mill scale a whole lot better than short circuit MIG. Sometimes, like on pipe welds, you might do a TIG root pass and you might follow that up with a hot pass using TIG to put a little bit more metal in there, but then you might switch over, for the sake of productivity, to dual shield flux core. Then you'll get finished a whole lot quicker!
It's really amazing how much metal dual shield flux core can put down. Very little cleanup too, I mean a rake or two with a chip and hammer and it's ready to come back with the second pass or the third pass, or whatever. 
This is almost the same technique you saw me using with a short circuit MIG a while ago for the cover pass pipe:

  • use a slightly longer stick out 
  • same shielding gas c25
  • and it's just a good hot puddle with very little cleanup.  

Does a great job and you can get finished with a job quick. And if you're in business to make money, and let's face it who isn't in business to make money, this is just one of those processes that gives you options.  And here we're running off a small machine a Lincoln 210 mp, it does a great job fills that pipe up quick.

Stick Welding aka. Arc Welding, Shielded Metal Arc Welding  (SMAW)

Stick welding the bread and butter process, also called shielded metal arc welding. The goal when I was in school is to be able to pass a 6g test with a 10 root, that's what was in demand and that's also in demand today 40 something years later.
And so I had to do a lot of welding before I got to this, I had to use a lot of (you know) different rods in 7018 t-joints uphill overhead and everything. But this was the goal: to be able to put a root pass in with a 60-10 on a 6g pipe test because that's what paid the money that's where the high-paying jobs were.
It's good to be able to go uphill because some codes require the root pass to be put in uphill. Others like api 1104 (the oil and gas industry) are typically downhill: same rod, sometimes a bigger rod (in this case a 532 going downhill on 12 inch pipe). But you need to have the skill of being able to put a root pass in uphill or downhill with a 60 10  and that will get you paid, that will get you a better job. 

Here's a hot pass on that 12 inch pipe, incidentally hot pass goals are mainly: 

  1. don’t leave any void or slag behind, or cold lap or anything.
  2. don’t blow through or remelt or reconfigure the root. 

So that requires a little bit of skill in body positioning: how to move out with adequate speed, hold the right angle, the right arc length, so you don't screw up the root pass.
Even if you can pass a pipe test and you become a pipe welder you might be called upon to make structural welds. I know I was a pipe welder, pipe fitter, but I had to weld pipe supports as well. For long periods of time actually - there were months at a time when I didn't do anything but 70 18 on pipe supports, so it's good to have that skill as well. 
An awful lot of structural welds are not single pass welds because the structure itself might be it might be three eighths, half inch, one inch, two inch, three inches thick or thicker. So, you're going to have to do multi-pass welds with 7018 or maybe even 110 18 (low hydrogen rods), so learning how to stack beads evenly, make multi-pass fillet welds in flat, horizontal, vertical, uphill and overhead is a useful skill and it will pay off in the long run. 

For 7018 I had just found that you know running it kind of on the hot side for flat and horizontal will help a lot, and don't be scared of the heat on overhead. You see me doing a cut polishing etch here too. And you can really tell each layer of that weld, you can see the root pass and the subsequent two passes. And that very informative, that's very instructive: to do a cutting edge right after you weld something you can really tell what happened.

[Visual of narrator showing welding movements by drawing ^ upwards along the welded join before demonstrating]

For vertical uphill with 7018, this is a technique that works for me, and you don't really have to do much of anything, but it's just a subtle movement (not real huge movement), just a little movement that kind of keeps you uniform. 

This particular weld was done with 532 7018 as is this overhead joint here. This is my friend Andrew Cardin. 165 amps here with a 532 7018 and we're using up a lot of used rods, so stubs, so it's like a ton of tie-ins on this joint. It's a three-pass overhead t-joint, we're using a nice tight arc with not much rod angle, good hot amperage. And by using all those rod stubs we've got a lot of practice with restarts on this weld. There's a ton of restarts there, but you can't really tell it too much. Practicing your restarts is fundamental to stick welding. 

Here we're using the 532 again 175 amps because the metal is a little bit thicker, that's a one-inch-thick base plate. But the same things apply whether you're on round or on flat structural shapes:

  • use a tight arc
  • don't get carried away with your rod angle
  • and use enough amperage. 

Use pretty much the same amperage as you would use for flat and horizontal for overhead, but that's where that tight arc really comes into play. 
And I can't emphasize it enough practice your restarts! 
You'll always have to make a lot of restarts when you're in tight spots and being able to make a good restart is huge.
Some rods don't lend themselves to welding vertical, uphill, and overhead (and all that). This is one of them… This is a big 3 16th diameter 7024, it's pretty much for flat and horizontal welding. And it’s kind of really for flat welding because as you start to weld even a little bit horizontal it can swirl around and get crazy with you. But, it will lay down a lot of metal, it'll put down a big huge bead, with a lot of heat input. 
Now there's also times when you want to use a smaller rod. A 332 7018 is a super useful rod, 90 amps is a good hot setting for that. And there's a vertical weave - this is done a lot on schedule 40 and schedule 80 pipe, but also on heavy equipment repair on gouged out cracks and things like that.
And this is just a 1/8th  7018 uphill practice pad a bead with 125 amps, which is something I highly recommend. If you're having any trouble at all welding vertical uphill - pad beads: get some seat time, get some hood time, get plenty of practice.

Video source: weldingtipsandtricks. (2021, June 12). Different types of welding [Video]. YouTube. https://www.youtube.com/watch?v=Ap5G9wDNL4E

Welding is a joining process in which metals, or plastics, are heated, melted and mixed to produce a joint with properties similar to those of the materials being joined.

There are three main components needed to create a weld. These are:

  • A heat source such as an electric arc, a flame, pressure, or friction. The most common heat source is an electric arc.
  • Shielding, which is the use of gas, or another substance to protect the weld from air as the weld is being formed. 
  • Filler material, which is the material used to join to the two pieces together.

Other processes that join metals together include:

  • Brazing is the joining of metals with a filler metal having a melting point above 450°C (842°F), but below the melting point of base metals. 
  • Soldering is the joining of metals using a filler metal with a melting point below 450°C (842°F). The joined metals can be different metals. 

For more information about welding, the Canadian Fabricating and Welding Magazine offers a great series of videos on different topics of interest including automation software, cutting tools, fabricating, health & safety, metal finishing and metalworking. Check them out!

Another important aspect for welders is the Red Seal Program. If you would like to know more about the Red Seal Occupational Standard, the Essential Skills and Job Market Reports, read more from this link, Red Seal Program.


From: CCOHS: Welding - Overview of Types and Hazards

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