PDA

View Full Version : Welders - Please Critique my Welds!



DeepBlue68
05-03-2006, 07:17 PM
Anyone who has any TIG experience, I'd love to hear your thoughts/comments/tips/etc on two T-joints I welded at my welding class last week. I'm in my second welding class at a local junior college, and I've been working solely on TIG the last 5 or 6 weeks. It's taken me about 2 classes to finally get my T-joints looking halfway decent (IMO). Here's a couple I did. I apologize in advance for the crappy pics...I was having a lot of trouble getting any decent ones.

I've done steel, stainless, and aluminum, and stainless is by far my favorite to weld so far. On the stainless piece, I know I got the right side a little hot since it's kinda grayish colored. I'm hoping to start TIGing on stainless 2.5" tube pretty soon because I wanna build my own exhaust from the headers back. It'll be a big undertaking, but I'm a pretty patient person when it comes to this kind of stuff.

The first is an A36 1018 CR Steel using a 2% thoriated (IIRC) tungsten and 3/32" filler rod.

The second is a 1/8" 304 (I think :confused: ) Stainless Steel also with 3/32" filler. Believe it or not, that was the first T-joint I tried with stainless, so I was pretty happy with the result.

Anyway, let me know what you think! Thanks guys!

Camaro Zach
05-03-2006, 07:34 PM
By no means am i an expert, but i would try using a bit smaller filler. something like 1/16" What size Tungsten are you using? Also instead of washing the puddle around you might want to try keeping it in the same place and just dabbing the filler. (will be easier if you switch to a smaller filler) Other than that it looks great, no undercutting and you now the heat.

05-03-2006, 09:31 PM
The side to side technique you're employing right now is used for cover passes on multi-pass welds only, and is normally done much colder than the root and fill passes. For a single pass weld, do not use this technique. All you're doing is multiplying your chances of not getting penetration at the root and putting more heat into the weldment than necessary. Also increasing your chances of undercut.

Atleast you can go in a straight line. That seems to be beginner's biggest problems on average.

And like Zach said, smaller filler. In the first picture, the start of the weld looks way too cold, which is probably a combination of filler size and the weave pattern. could be the picture too though.

Also, 1018 (http://www.matweb.com/search/SpecificMaterial.asp?bassnum=M1018A) and A36 (http://www.matweb.com/search/SpecificMaterial.asp?bassnum=MSA36C) are two different alloys.

DeepBlue68
05-03-2006, 11:14 PM
Zach, thanks for the tips! I'll try that out at my next class.


The side to side technique you're employing right now is used for cover passes on multi-pass welds only, and is normally done much colder than the root and fill passes. For a single pass weld, do not use this technique. All you're doing is multiplying your chances of not getting penetration at the root and putting more heat into the weldment than necessary. Also increasing your chances of undercut.

Also, 1018 (http://www.matweb.com/search/SpecificMaterial.asp?bassnum=M1018A) and A36 (http://www.matweb.com/search/SpecificMaterial.asp?bassnum=MSA36C) are two different alloys.
Matt, thanks for the advice. Is the proper technique for a single pass weld to do a straight pass and dab the filler into the puddle (rather than using a weave with a lay-wire technique, like I was doing) like Zach mentioned?

Also, what about the HAZ? I've been told that you don't really have to worry about that until you're getting really good and wanting to produce very high-quality welds, but that just doesn't seem true to me. I'd think that it would be important no matter what (esp. in stainless). Your thoughts?

Thanks for the comments guys...keep them coming! :bananna2:

05-04-2006, 07:53 AM
Some guys like to use 'lay wire', but I like to physically see the arc get into the root before I add filler. Much more control that way too. Also, with TIG, moving the torch along in a straight line should be done on any pass in a multi-pass weld except for the cover, if applicable. See attached.


Also, what about the HAZ? I've been told that you don't really have to worry about that until you're getting really good and wanting to produce very high-quality welds, but that just doesn't seem true to me. I'd think that it would be important no matter what (esp. in stainless). Your thoughts?


Perfect practice makes for perfect performance.

DeepBlue68
05-04-2006, 10:40 AM
Matt - damn, that is a really nice weld in that pic you attached. Can you tell me how it was done (technique, filler, material, machine settings, etc.)? I'd love to be able to get to that point with my welding skills.

What do you think about washout/washover (can't remember what it's called - whatever the technique is where you go back over a pass with just the torch to improve the look of the bead)? My welding prof said people do it basically just to make the weld look nicer, but I have to imagine that has some impact on the quality/strength of the weld. I know he said they won't grade students' welds that have been washed over.

BB69
05-04-2006, 10:46 AM
I just finished my class two weeks ago, I have been meaning to post some more pics. Anyway, one of the instructors gave me a few tips that really improved my stainless welds. I went from a #8 cup to a #10, and I increased the angle of the torch to the work pieces slightly. Using these two changes, I was able to go from the dip and wash technique you were using to keeping the torch straight and just dipping. At the same time, the color of my welds increased dramatically. Finally, as Matt said, practice seems to be the only real solution. Even my aluminum welds looked better after the additional 7 weeks of welding stainless.

Good luck.
Ken

05-04-2006, 12:26 PM
Can you tell me how it was done (technique, filler, material, machine settings, etc.)?That was a 3-pass on 1/2" mild steel plate, and I ran it probably two years ago, but I'm sure it was something like 200 amps, 3/32" 2% Thoriated tungsten, 1/16" ER70S-2 filler, etc. 200 amps is too cold but for what it was, it didn't matter. Torch was moved straight along the weld and filler was 'dipped' in. (Any weld of mine you see, you can safely assume that's how it was done.)


What do you think about washout/washover... I don't know what it's called either, I doubt it even has a real name because no good welder will do it, save for a couple unique cases; One case is Hogans multi-pass their manifolds where the runner meets the plenum and the head flange so the porters can do whatever they need at those transitions and still have a solid weld left. The last pass (cap) they put on it is a huge weave to wash everything in together.

Ken, just a guess, but angling the torch more probably only helped you because it let you see better. As far as gas coverage, positive travel angles will, if anything, hurt it because less gas will be lingering over the cooling weld, and more gas will be pushed ahead of the weld where it isn't needed.