What makes a good weld?

[tompatjr]

Could some of you that know what your talking about post some pictures of what a "good" weld is supposed to look like and maybe a description of what to look for in a weld. I'm asking because I see all different kinds of welds on this forum. I have a freind who is a professional (at least that what he does for a living) welder and most of the time when I show him a part that I have bought he looks at it and in says what they should have done.

Maybe some different types of welds, mig, arc, tig, what ever else is common.

[OT]

The first picture are "good" TIG welds.
They have full penetration, consistent beads, and have no porsity.
The second picture is a "good" MIG weld.
It has full penetration, a consistent bead, has no porosity.

[BrettM]

can't always tell penetration from a visual. destructive testing (or Xray if you're fancy) is often required, and should be done many times while you learn so you can understand better what works and what doesn't.

[Capt. Nemo]

I don't know much about welding to be honest. I've done alot of practicing and welding on my own junk, but I wouldn't weld anything that mattered on anyone else's rig.

The following pics are from work done by MAD4WD. The link where I borrowed the pics from can be found here:

http://www.pirate4x4.com/forum/showt...&highlight=hi9

[CanMan]

Them guys who make sheetmetal (aluminum) intake manifolds for drag cars do some sweet work. Aluminum always looks nicer when done, IMO.

[OT]

Well, yeah, because, Al. flows better.
I actually learned on Al., then went to steel.
For some reason, steel always seemed more difficult, on which, to get a good weld.

To me, stainless is the penacle.
I used to know a guy that could butt weld large diameter stainless tubing and I GUARANTEE you wouldn't be able to find the seam. (no filler rod, of course)
I got pretty good with SS, but Aluminum is still my favorite......

[BrettM]

Originally Posted by Okie Terry

Well, yeah, because, Al. flows better.
I actually learned on Al., then went to steel.
For some reason, steel always seemed more difficult, on which, to get a good weld.

To me, stainless is the penacle.
I used to know a guy that could butt weld large diameter stainless tubing and I GUARANTEE you wouldn't be able to find the seam. (no filler rod, of course)
I got pretty good with SS, but Aluminum is still my favorite......

weird...

TIG I assume?

[ChicksDigWagons]

Originally Posted by BrettM

weird...

TIG I assume?

Kinda hard to MIG without filler rod Brett

To contribute. The best source for welding knowledge I've found is Lincoln Electrics website

http://lincolnelectric.com/knowledge...op-welding.asp

Lots of information, but you have to wade through the stuff targetted at big time manufacturing to find some of the stuff more applicable to the DIYer. But there is no replacement for practice, have your welder buddy critique your welds, learning from a pro is better than anybody on here can provide on the internet.

[BrettM]

Originally Posted by ChicksDigWagons

Kinda hard to MIG without filler rod Brett

I was asking about him, not his friend. jerkface.

[ChicksDigWagons]

Originally Posted by BrettM

I was asking about him, not his friend. jerkface.

Well you didn't say. doublejerkface.

[OT]

Originally Posted by Brett

I was asking about him, not his friend. jerkface.

Yeah, TIG.
I stated out on flat Al. plate and probably ran twenty feet worth of beads before I ever tried to put two pieces together.
Mild steel took considerably less time to get down, but it seems like it took forever to get a nice bead lain out.
After all that, stainless turned out to be a breeze.

[ZPD]

I spent the first 5 years of my career in the automotive industry. Among other things we welded parts on automated lines. I had 46 MIG welding robots and a probably about 10 spot welding robots working ~20 hours a day. One of my major responsibilities was installation and programming of the robots and ensuring that the positions and settings resulted in good welds. We used destructive methods to ensure quality (break tests and cut/etch). After all that I don't claim to be an expert. I only have good experince with mild steel (which is 99% of what I need anyhow). Anyway through that expereince I learned that you can look at a weld and say that it is bad but you cannot look at a weld and say it is a good weld. The best way I have found is to watch the weld while it is being done. When I welded by hand or worked with a robot, I would watch how the puddle forms and how it ate into the base material (penetration). If the puddle was consistent (shape and height- not really high with a sharp peak and not shallow below the surface of the base metal) and the penetration was 75%-100% into the base material generally it was a good weld. Generally is the key word because if the HAZ is too large then all you do is weaken the base material.

[OT]

HAZ= Heat Affected Zone

Just thought I'd clear that up before someone asks.

[BrettM]

Originally Posted by ZPD

Anyway through that expereince I learned that you can look at a weld and say that it is bad but you cannot look at a weld and say it is a good weld.

EXACTLY!

I've been running a robot MIG welder for a few months and there have been a couple times I've brought what looked to be a perfect weld to the quality control guy and he'd give them one little bang on a table and it would fly apart. Then I'd take one of the same parts and show it to some of the guys that have been welding 50 hours a week for 20 years and ask them if it looks good, they'd say it looks good, then I'd give it one little bang and it'd fly apart.

Looks can be deceiving.

[OT]

Originally Posted by BrettM

EXACTLY!

I've been running a robot MIG welder for a few months and there have been a couple times I've brought what looked to be a perfect weld to the quality control guy and he'd give them one little bang on a table and it would fly apart. Then I'd take one of the same parts and show it to some of the guys that have been welding 50 hours a week for 20 years and ask them if it looks good, they'd say it looks good, then I'd give it one little bang and it'd fly apart.

Looks can be deceiving.

That's because you suck.
But, I rule, you see?