Different welds, metals, welding practices, and more are explored in Deconstruction, a series from DIY Network. This episode focuses on various aspects of welding. The full transcript for the video is below, as always. Enjoy!
We’re putting welding to the test, and it’s not just the pros you’ll find under those heavy duty helmets. These days lots of hobbyists are taking up the torch, and all the home improvement stores now carry welding supplies to make cool projects around the house.
So what is the strongest way to join metal? Does an epoxy weld compare to an arc weld? We’ll let cinder blocks and gravity decide.
Three, two, one!
If you think all welds are alike, think again.
Do you know the difference between stick, TIG, and MIG?
When sparks ignite, why are some metals harder to extinguish than others?
Magnesium meets CO2 in an icy showdown.
How is it possible to weld underwater? Why won’t the fire go out? I’m suiting up to find out.
We’re deconstructing welding, next.
We’re exploring the science of home improvement.
Because to understand what you’re building, sometimes you’ve just got to take it apart.
Hey. I'm Matt Blashaw. Alright, now if you're a seasoned DIYer, you're definitely not afraid to pick up a hammer from time to time, and you probably know a little something about electrical or even plumbing. The one skill you may not have mastered is welding. Today we're gonna spark this thing up – not only to show you the "how" and "why" behind it, but to have a little fun too.
So what exactly is welding? Well, simply put:
Welding is the process of joining two or more materials through heat and/or pressure to form a permanent bond. Whether it's a small home welder or an industrial-size for building skyscrapers, the science is the same.
To understand how it works, think of a light switch that flips on to complete a circuit. With an arc welder, a ground wire is clamped to your work surface. When the electrode comes close to the work-piece, an electrical arc flows from the positive electrode to the negative ground. The wire in the torch and the two pieces being joined melt together to form the weld pool. As that pool cools and solidifies a strong molecular bond forms, holding the two pieces together.
Alright, check this out. If done right, a welded joint is actually stronger than the two pieces of metal that it joins. To prove this, we're going to Lincoln Electric in Cleveland, Ohio. These guys are experts in arc welding.
It's the self proclaimed "Welding Capital of the World."
With 2 million total square feet of factory floor, this Cleveland, Ohio based company not only manufactures but teaches welding and tests their products as well.
Lincoln Electric is the largest manufacturer of arc welding products in the world.
To date, Lincoln Electric has manufactured over 10 million arc welding machines. Everyday they make enough welding wire to wrap around the earth twice.
Welding is everywhere around us. The cars you drive, the bridges you drive over, the buildings you're in, the pipelines that bring your energy and your water are all welded together. Life wouldn't be the way you know it today without welding.
Lincoln has been in the welding business since 1900. . .
The equipment was big; it was cumbersome. Probably wasn't as comfortable to use.
. . . and they've come a long way. Lincoln now makes three main types of arc welders:
- Stick
- Wire machines, including MIG and flux cored, and
- TIG
Stick welding, also known as shielded metal arc welding, is perhaps the most basic.
When I make this connection to the work, the electric arc starts forming across and creates an
intense heat and the rod starts melting.
The flux covering the rod or electrode vaporizes to form a cloud; that cloud keeps airway from
the weld pool.
If the molten puddle is contaminated with the air, the oxygen, and nitrogen, you'll get holes in
the weld and the weld would break and the things wouldn't hold together.
As the weld cools, a protective coating called slag forms on top.
Then when the slag is solidified or cooled, it has a crusty film on it that we must knock off.
Stick welding was invented first, but another type, MIG welding, is actually the most popular today.
When I pull the trigger the wire comes out of the nozzle. The gas comes out around the wire. The advantage is you have a continuous spool of wire so you can start a weld and continue it in very very long durations without running out of any material.
MIG welding is used in most robotic manufacturing. In fact, your car is held together almost
entirely with MIG welds.
The third type, TIG welding, is the most high tech.
It's commonly used on alloys, such as aluminum and stainless steel. With a TIG weld, a tungsten electrode melts a hand-held filler rod, a foot pedal controls the amount of electricity used.
I get the arc hot enough to melt the material that I am welding and add the filler material to the puddle.
Making top-notch welding machines is just part of what they do at Lincoln Electric. They also test the welds their products make.
That's where this guy comes in.
Jeff Major. Research Engineer, Microscopy and Mechanical Engineering.
Jeff's job is to find out what it takes to break a weld.
It gives us an idea of how these materials are going to perform in environmental conditions.
The first test checks the tensile strength of a weld.
We would come in and essentially take out the piece of metal from here.
Then the piece is pulled like taffy until is reaches a breaking point at 70,000 pounds per square
inch.
The higher the strength level the more rigid the material is. 70,000 PSI is right around the mid-strength level.
Another test, called the Sharpy V-Notch test, measures a weld’s resistance to impact.
It's a pendulum drop that hammers about 70 pounds, and it measures the impact through a pendulum dial gage.
In the real world, here's what they want to know.
Is it better for an auto-body to crumble, or is it better for it to snap in half? I think we all know that it's actually better for an auto-body to crumble, which is a measure of toughness. It's the ability for that system to actually bend without breaking.
Whether their breaking welds or building welding machines, the folks at Lincoln Electric have got this stuff down to a science.
Every welder has to have a helmet. Why?
Just like the sun, a welders arc creates an ultraviolet light. Without the right eye protection, you can get what welders call an "arc eye." They say it's like getting a sunburn on your eyes or getting hot sand poured onto them. Not cool.
Coming up: Did you know you could weld without a welding torch?
You might want to wear your nifty shades there.
I got them on.
We're breaking out the thermite to fuse these two metals, and we're testing the: Will an adhesive weld from a tube really match an arc weld? Cinder blocks and gravity provide the answer in a head-to-head test.
Three. Two. One. That's gonna leave a mark.
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If you're new to welding, don't forget to button up. You need to cover your neck to prevent burn from UVI rays. Special flame-resistant jackets are a good idea, and never, ever wear any polyester. When it heats up it can melt to your skin.
One of the earliest forms of welding was used over 100 years ago on rail lines just like this one. It used a pretty serious chemical reaction.
Before there were welding torches there was another way to fuse metal: with a fiery, chemical reaction. We're gonna try to react one of those welds for ourselves.
Matt: OK Joe. What are we lighting up here?
Joe: We are going to be lighting thermite. Which is essentially iron oxide and is mixed with some aluminum powder.
With a burning temperature of over 4500 degrees, thermite was invented in the 1890's and used as a way to add railroad lines together.
Matt: Okay, so that's even so hot that's it's going to bond those to metals together?
Joe: We'll bond them together, yes.
Matt: So I imagine that's gonna be pretty bright?
Joe: It's. . . yeah. You might want to put those fancy little sunglasses on.
Matt: I'm gonna put these one, and I'm gonna let you do your thing and I’m also gonna step out of the way.
Joe: Alrighty.
About 4 ounces of thermite sandwiched between two pieces of steel with a magnesium wick and you've got a ready-made weld. By the way, don't try this at home. The reaction is so hot and powerful, within seconds the two pieces of steel melt together and form a permanent welded bond.
Matt: Wow. That is one serious weld, dude.
Joe: It's pretty good. It's a little primitive, but as you can tell it worked.
Matt:Yeah it get's the job done.
Joe: It does.
Here is the question: is welding the only way to create a super-strong joint?
Some epoxy adhesives on the market claim to be a good alternative to welding. it takes two materials together to make the permanent bond. One is a liquid steel, or epoxy resin. The other is a hardener. The epoxy weld takes up to 24 hours to cure, and after that it's water-proof, acid resistant, and can withstand heat up to 500 degrees.
But is an epoxy weld as strong as an arc weld? To deconstruct this question, we built two steel-framed cages: one connected with MIG welds, the other with epoxy. Each cage is put together with 32 welds. To find out which is stronger, we concocted a mix of gravity and cinder block. First up, we're testing the strength of the MIG welded cage.
My buddy Jason is helping me out.
Matt: Alright, so how far are we up here?
Jason: About 20, 25 feet.
Matt: Alright, and how much does this cinder block weigh?
Jason: About 20, 25 pounds.
Matt: Well let's introduce it to the cage.
Jason: Ok, are you ready?
Matt: Give me a countdown.
Jason: Alright. Here we go. Three. Two. One.
Jason: Look at that!
Matt: Oh! That's gonna leave a mark. Wooooo hoooo! What a shock!
As it drops 23 feet, the
cinder block reaches a speed of 40 feet per second. Accounting for weight and gravity, our nifty physics calculation tells us the energy and impact equals 622 foot pounds. That's a greater impact than some hydraulic hammers have.
Matt: Look at that. This thing is pretty intact. It bent a little bit, but none of the welds are even. . .
Jason: They're all intact on this side over here.
Matt: Wow. Now I want to test this epoxy, because I want see if what they say is true, if the epoxy is going to withstand that much force coming down from the cinder block.
Jason: We shall see.
Matt: There goes the epoxy weld.
Jason: Three. Two. One. Here we go. Ooooh hooo ooo!
Matt: Total destruction! That wasn't even a contest. Look at these things. That didn't even have a chance. So [we've] definitely proved the point that epoxy welds are not so strong as regular welding.
It's pretty obvious from this test that metal welds are stronger that epoxy welds, but just how strong are they?
Matt: We're twice as high.
Jason: Yep.
Matt: Let's see if we can break this thing.
Jason: Alright. Three. Two. One.
Matt: Ohhh hooo ohhh. That cage was solid.
Alright, back to the physics. Dropped from 45 feet, the cinder block reaches a final velocity of 54 feet per second. That means it hits with a force of 1100 foot pounds. That's nearly double the force of the first drop.
Matt: Look at that thing. It stayed -
Jason: You know what?
Matt: – in tact.
Jason: The only welds that popped are the tack welds that held the plate in place.
Matt: But nothing structural?
Jason: No.
Matt: I still think there's more we can do.
Jason: Three. Two. One. Go.
Matt: Woo hooo ha ha! I love it!
Coming up: You know what a bridge means to a welder?
We're taking this welding show down under.
But isn't it hazardous to mix water and electricity? Only five schools in the country train underwater welders, and I'm getting a personal crash course at one of them. And later on: what if sparks turn to fire? You might be surprised at how some metals react.
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When a bridge or ocean tunnel needs repair, it may call for a specially trained welder. Using electricity underwater takes a highly skilled tradesman.
We're here at the Divers Academy International just outside of Atlantic City, New Jersey, and we're about to get to the bottom of this. Let's check it out.
The Divers Academy International is one of just five schools in the country that teach commercial diving, including a course in underwater welding. More than 200 divers a year are trained here.
Matt: This is like an interactive classroom. Everything is all ready; it's hands-on.
Tamara Brown (Tammy): Everything's hands-on here. We want to get you involved. The more experience you have the more comfortable you are, and you're going to produce a safe, wet weld.
To be an underwater welder you've got to be tough, both physically and mentally. To get there, these students go through a rigorous 5-month training program, and safety is paramount. To keep molten metal hot enough in cool water, they're welding with 400 amps, 10 percent more than above ground.
Matt: Alright, so now I know welding is about electricity. Right?
Tom Connelly: Right?
Matt: So how come when you're in the water, you don't get shocked? I don't understand it.
Tom: Ah, that's a good question.
There are two good answers.
First. . .
Tom: The difference of the two electrode holders. . . we have the regular electrode holder. You can see it leaks electricity if it was to get wet. On the underwater electrode holder you can see it's all plastic and waterproof. Therefore no electricity can leak out into the diver’s hands or enter into the diver’s body so he cannot get electrocuted.
Second of all. . .
Tom: While the diver is maintaining the arc he cannot turn his back on the ground. Here's our ground clamp, the electrical field is directly in this general area here.
Matt: So it's circling here and not through me.
Tom: Right.
And if you do turn away from your work. . .
Tom: You are directly in the middle of everything, and you are feeling the full force of this electrode.
Matt: So I'm not having a good time at this point.
Tom: No you're not. You're miserable.
Matt: So let's put this thing to use.
Safety is one thing, making good welds is another. So I'm getting comfortable with the equipment.
Tom: That takes practice. Slow it down a little bit.
After a quick practice bead, it's time to get wet.
Matt: Now we're heading underwater, right?
Tom: Oh yeah.
Matt: That's the real task.
Tom: Oh that's the task.
Training for this job is no joke.
This thing is heavy.
Just getting into the dry suit is tough enough.
Matt: Woo! I can't wait for this.
Tammy: You want to put the neck down on next.
Matt: Blue a good color on me?
Tom: Yeah.
Matt: Boy I'm loaded up with equipment.
Tom: Can you move?
Matt: Yeah, uh, I think I can.
Tom: Then it's not enough.
Matt: Ha ha ha!
With over 125 pounds of equipment on, it's easy to sink to the bottom like a rock. Luckily for me, we're only going down about 15 feet.
Tammy: Ok Matt, this is it.
Dispatcher: Diver is leaving surface.
In the open ocean, commercial divers can reach depths of 300 feet and stay down 4-5 hours at a time.
Tom: We're going to start working down here. We're going to use everything I have taught you up top to strike an arc down here. Okay?
Matt: Roger that.
Once the stinger and ground are loaded, we secure the the ground clamp and load the stinger. A call to the surface lights it up.
Tom: Make it hot.
Tammy: Top side making it hot.
Matt: This is great. I mean,this is really amazing to see the actual arc underwater. Tammy is this what you call, "getting it done?"
Tammy: It's getting the job done Matt.
Cool stuff, but for me once is enough.
Tom: Good dive Matt.
Tammy: Good job.
A day at Divers Academy is just a sample of what wet welders go through everyday. And I can
honestly say I'll never look at a bridge over water the same way again.
For more info on welding and to see clips from other episodes of Deconstruction, just go to our
website DIYnetwork.com.
Coming up: A little welding safety. Cause where there are sparks, there can be fire. Not all metals react the same.
It's the 4th of July.
A lesson in dousing certain metal fires, next.
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When you weld you learn a lot about metals and how they react with heat and fire, for instance magnesium – a light alloy used in cars and planes.
With shielding gas, it's no danger to weld bulk magnesium, but you don't want fine particles an
d shavings on the work surface because they could ignite, and you can't fight the fire with water or CO2. Jason and I are lighting magnesium strips to see for ourselves.
Jason: Put our sunglasses on, and take that torch and ignite the end of this magnesium strip.
Matt: Alright. Light it up.
Jason: Here we go.
Matt: Yeah, look at it burn.
Jason: Get going. It’s gonna get bright. Here we go.
Matt: Yikes.
Jason: Alright, we got it. We'll drop it in water and see what happens.
Matt: Wooo hooo wooo hooo! It's the 4th of July.
Jason: I love it.
Matt: Wow. That water is actually feeding that magnesium.
Jason: That's right.
Matt: Woo!
Because magnesium burns at such a high temperature, it actually splits the HO2 and water into hydrogen and oxygen. The oxygen is used as a fuel source, that's why we get a flare-up. So tossing a bucket of water on a magnesium fire – not a good idea. Well what about a CO2 fire extinguisher? Let's give it a try. To make this a little less messy, we're using dry ice blocks – which are carbon dioxide in solid form.
Jason: Just ignite the end of the magnesium stripping. Alright so I'm going to put it right here in the center, and get that lid on. Check this out.
Matt: Look at that thing glow. Wow it's feeding that fire.
Jason: That is so cool.
Matt: Awesome!
Just like the water, the burning oxygen causes a flare, while the carbon is released into the atmosphere.
Matt: The bottom line here is that, don't try to put out a magnesium fire with water or CO2.
Jason: Well that's true. Some extinguishers will do the trick. Uh, you can throw some sand on there or smother it. Uh, but you're better off probably just letting it burn itself out.
Matt: Great solution.
Just so you know, there are class D fire extinguishers that will put out a magnesium fire. The key ingredient is sodium chloride, also known as table salt.
So as you can see, magnesium is some pretty powerful stuff. See ya next time.