Technical Not a typical Step Notch question

20cfm.

 

On any one given machine flux core will weld hotter and with more penetration than solid wire. That due to the switching of polarity. Everything else applies, clean, heat, wire speed, travel, inclusions.

If you make yourself a welding test and put it thru a bend test procedure it's either going to pass of fail. There's no ABCDF grade scale, if it's not perfect it fails. Run the test with solid core wire or flux core and its still pass or fail.

A pass is a pass is a pass and no one pass is better than another pass and any pass is better than any fail. It's pretty simple.

 

Not sure they even used a welder there. I'd guess mortar from the looks of it.
I'm assuming that is a joke.

As for cfm for c25 gas I am always around 15/16. Shouldn't ever need to crank it much higher as it just wastes gas. I use a mm210 so I would refer to the owners manual as the mig gun/nozzle may require a higher flow rate if it isn't efficient at coverage from atmospheric gas.


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I butt welded a single side of 3/16 steel and bent it in the direction of weld and it broke down the center of the weld bead. I butt welded both sides of 3/16 steel and bent it back and forth several times and it held. Both flux core. These were not beveled, just square ends with about 1/8 gap. What does this tell me?

 

Your welder does not produce enough heat, or you are on the wrong setting.

 

Again, It depends on what the back side looked like.
If it was still identifiable as the joint you didn't get deep enough and a bevel is the proper prep for that joint and the proper correction for that failure.

 

Thanks I'll try and bevel some spare pieces and weld them and see if I can post some pictures since I didn't get to last time you mentioned it. My "bend test" I performed was simply holding one piece in a vise and bending the other piece with pliers.
Could the weld wire be a factor at all?

 

If the bead put into a butt weld doesn't go completely thru the plate it will crack right there. Think of it as a score line when cutting glass, one little scratch on the glass and it snaps cleanly on that line

This is a picture of the inside of a pipe welded on out side. See how looks welded from the inside too? It's not, the weld penetrated clean thru the joint to the inside, it was beveled. The backside of your test piece should look the same , just like someone welded the back side

 

Years ago when I was practicing to get ready for the 6G pipe test, the thing that took me the longest time to consistently get right was the root pass. Finally quit even running out the full weld and would just run the root, cut coupons, grind the back side, and bend them in the fixture. When I got to the point where the root was good every time, particularly on the section where you run uphill at a 45* angle, running the filler and cover passes was a piece of cake.

Later on, 2-3 years after I was certified and had been stick welding pipe regularly, I was going to build a frame to mount some pumps and other equipment using 3 X 1/4 and 4 X 1/4 wall square tubing. Was doing that in the shop rather than on site, and since most every joint was a 90* with fillet all around I decided to use a 250 amp wire machine to speed things up and get away from slag busting. Didn't really have much wire experience on anything other than a bunch of 16 ga, but what the hell, even a monkey can do this stuff.

Welds came out looking great. Painted it and left it to dry overnight. Picked it up with a forklift the next day to load on a flatbed and send to the jobsite. Didn't have the forks all the way under the far side, and when it was about 18" off the floor it slid off and banged on the floor. I get off the lift to see if it needs any touch up paint where it hit the floor, and I notice a place where it looks like the edge of a fillet has a hairline crack where it joins the tube. Never would've noticed it had it not been for the bright yellow paint the customer wanted.

So I set the thing down and grab a 16# no bounce sledge and give it a couple whacks. Friggin cracks anywhere the hammer lick had put a weld in tension. Hit it from a different angle and get more cracks. Time for a major Oh Shit.

One of our crane operators had a bunch of MIG experience on a previous job so I called the yard and asked him to come to the shop. He takes one look and says he thinks he knows the problem. Tells me to grab a couple tube scraps and make a fillet just like I'd done on the frame while he watches. I ran maybe 2 inches and he says to stop. He says I've got the gun at the wrong angle and I'm just welding on the weld rather than getting penetration into the material. Sure enough we stick the sample in a vise and whack it with a hammer, and it falls apart showing the weld had about as much penetration as a bead of Elmer's glue. Damn bead looked really nice though. Only problem was it wasn't welded to anything but itself.

So Paul shows me the proper gun angle for pulling the weld on heavier stiff like this. I weld up another sample all around and we beat the living hell out of it, and its rock solid. Started over from scratch and built the entire frame again.

And yeah, there is a point to this diatribe. When MIG welding anything structural, test and qualify your damn procedure and don't just assume its good because it happens to look good. And most important, the fact that you may be certified on one process doesn't mean shit on another process. It just makes you overconfident. If I'd made this same mistake on a car frame, and didn't catch it, it could've left me or someone else dead or ruined for life.

 

Chances are high that you never burned deep enough so it didn't thoroughly melt the plates all the way to the other side. That leaves a line, a stress riser, which starts a crack so easily. Properly done it should basically look just like a smaller weld on the back side. See the example 32Vicky posted.

 

So here's a quick and small, beveled piece I butt welded. Not to saying it would look better, but I could hardly see the base metal when I was burning this. I had to adjust my helmet afterwards. It held A LOT better than the previous one I mentioned with the square edges. It didn't penetrate the back much at all, I probably passed to quickly. Towards the end I slowed down and it looks like it started to penetrate thru the back. I forgot to snap a photo after the bend test. I clamped it about 2 inches away from the weld, and it held and bent the base metal. Then I clamped it closer to the weld and with enough force it finally started tearing and broke across the bead. I also did a lap fillet weld and the held fairly well I think. I forgot why but I ran a small bead, stopped, then ran another bead on the other end, so it had a small gap between both beads. The smaller bead didn't penetrate that well. It bend both ends of the base metal as you can tell, before it snapped. I actually had to pry a screwdriver in between to get it to give. All these pieces are 3/16, with flux core, and I didn't really clean the metal of the black coating.




Weld held here, and bent the sides up
This is when weld started cracking

 

I don't wish to sound harsh but those pics tell me you're a loooong way off being able to carry out structural modifications or repairs on a car frame. Seek professional (welding) help before something bad happens, please, really.

Chris

 

No worries, I appreciate the opinions and honesty. I found this picture online, what does everyone think of this notch welding? I mean it looks very ugly, probably how mine may look if I welded it in. Can an ugly weld like this be as durable as a good looking weld?

 

Total shit

 

What am I looking at here?? And did that actually hold?

 

What.....stop before you die or kill an innocent bystander

 

This example is a great one that shows precisely why the Structural steel codes and standards such as the AWS D1.1 and CSA W59 do not have any approved welding procedures for GMAW short circuit transfer.
Far too much chance of fusion faults like this.
Fusion faults that an experienced well trained wire feed welder doesn't make.

Even so Short circuit transfer MIG is not acceptable for code related structural steel work.

 

Uhhhhhhhh,,,,,,, are you sure that's flux core? I'm seeing porosity in every weld like gas wire without gas and that's not good at all.

No offense meant but those welds are so bad I can't even figure out what you are doing wrong.

Is there anyone near you that is a decent welder that can watch/coach you for a few hours?

And NO a shitty looking weld is more than likely shitty weld all the way thru.

 

Is the polarity set right for flux core? Has to be opposite of what you run for solid wire.

 

Yes it's the NR-211 innershield wire. Just for the record, those two beads that are side by side was me making some spark to adjust my helmet. I did another fillet and it looks better (probably not as good as all these pro welders here) but non the less much better, but it too had 1-2 porosity holes... So I'm curious about that myself. Not saying the other welds don't have porosity, they may, but I did hit them with a chipping hammer and It made small craters, incase those were mistaken. I also did have a fan blowing to escape weld fumes. Yes the polarity is right, the clamp is + and torch is –.

 

I'll second what Da Tinman said... it looks as if you're using gas wire without the gas. Flux wire still creates a shielding gas 'cloud' around the puddle as the flux melts so it is possible your fan is blowing that gas away which could explain some of the problems you are having. In any case I would say DO NOT weld in a notch until you're confident in your welds. Even better, have someone who's experienced check out your setup, teach you some stuff and weld in the notch for you.

 

Well I guess I'll just go ahead and use this:

I can drill holes pretty well.