How does welding metal work?

[Squisher]

Originally posted by: Rubycon

Originally posted by: Jeff7

My high school physics teacher also did some welding. His detailing of the parts that suck: regular exams for skin cancer due to exposure to UV radiation, and having hot sparks fall on his shoe, which would then burn right through to his foot.

You forgot the part where the smokers forget and leave their butane lighter in a pocket and a spark nails it - BOOM! :Q

We've got this idiot at work that managed to not get a good seal on a torch and left it on his welding buggy where the gas rose to an overhang of a ill-fitting lid of a tool box and thus filled the tool box. When he held the torch away from what he was heating he ignited the tool box and BOOM. It looked someone peeled the box open like a sardine can.

 

[xXped0thugXx]

Originally posted by: Rubycon

Originally posted by: Jeff7

My high school physics teacher also did some welding. His detailing of the parts that suck: regular exams for skin cancer due to exposure to UV radiation, and having hot sparks fall on his shoe, which would then burn right through to his foot.

You forgot the part where the smokers forget and leave their butane lighter in a pocket and a spark nails it - BOOM! :Q

someone has been watching a bit too much of Mythbusters. I've never seen this happen and I've been around welding and plasma cutting with a bunch of smokers and with lighters in my pocket (not even thinking twice) for quite some time

 

[miniMUNCH]

I weld (TIG mainly), braze (copper), silver solder every so often as needed for various ultra-high vacuum equipment projects in my lab.

I took a class & lab in undergrad and then continued to improve my skills thereafter... frankly, I'm not very good at all but my work is passable.

Welding is a lot of fun and you can make really good money.

 

[Evadman]

As has been said may times in thi thread, a properly created weld is stronger than the rest of the material.

The 'stacked dimes' that was mentioned is generally the result of a good TIG weld. However, it is very possible to create that design and have a poor weld.

<-- welds with MIG and Gas. Never tried TIG, needs more $ Has a 3/8" miller plasma cutter though. Best grand I ever spent. Some day you will see me in the news when I bust it out and write my name in the side of a car faster than you cn with spraypaint

 

[Tiamat]

as long as there isnt water/air/dirt trapped within the weld, it will be as strong as it can possibly be. If possible, a double bead inside and out can ensure a good seal such that "stuff" cannot work itself into the weld to decay it.

 

[skyking]

I took classes but I've been "farmer fabbing" or field engineering for a long time. Most of my projects have been completed with the common Lincoln 'buzz box', but I also have access to MIG and TIG machines.
It is true that most failures near a weld are right at the stress riser just at the edge of the weld area, not in the middle of the fillet.

 

[alkemyst]

Originally posted by: FoBoT
http://www.gowelding.com/weld/failure/failure.htm

yeah and glue is always weaker than the wood too right?

That link is about poor welds and improper ones.

 

[cherrytwist]

I had a lot of fun welding and worked as a welder/fabricator for a few years after attending tech school.

All of our certifications would only pass if the weld was as strong as the parent metal. They would take a 1" strip and bend it in a U shape. If the weld held and was clean of pitting, debris, etc., it passed. If it broke or was flawed, it failed. Fortunately, all of my samples passed (I had an excellent teacher).

Slightly OT:

I held 13 certifications in MIG, TIG, ARC (including pipefitting) and welded everything from 1/8"+ stainless steel, 1/4"+ aluminum to 1" mild steel, but got sick of 55-60 hour work weeks. Every shop I worked in had mandatory OT, often mandatory Saturdays. And the pay wasn't that great (I made much more waiting tables soon after).

Anyway, my interest in a sculpture class sparked (sorry, had to) my interest in welding and I hope to work again in a studio some day.

 

[nweaver]

I had the axle break on my trailer (it was an old break, that happened before I bought it). I got my "adopted" dad to weld it, he is amazing. I'll have to snap a picture or two...he calls wirefeed welding "cheating", and uses and old stick welder. He did an amazing job, used 4 sticks on the axle, getting material all the way through. I've seen some of the stuff he welded break somewhere else, it really depends on the metal.

 

[spidey07]

So are the realy pretty welds on high quality bicylce frames difficult to do? I would guess so being aluminium. They do looks like a neat stack of dimes, pushed over.

 

[alkemyst]

welding is not difficult usually (not discounting deep water, under hostile fire, etc). It's a skill though, so the more you have done it the better you are. I want to take a class one day on it.

 

[drnickriviera]

Originally posted by: spidey07
So are the realy pretty welds on high quality bicylce frames difficult to do? I would guess so being aluminium. They do looks like a neat stack of dimes, pushed over.

I still haven't mastered the basic skills of TIGing aluminum. The aluminum doesn't turn red hot like steel when you have it at temp. Next thing you know, you've added too much heat and you have burnt a dime size hole in the metal. Then the cursing starts.

Sometings I just sit there looking at the welds on my brother Serotta Titanium frame. They are absolutely perfect.

 

[Tiamat]

Originally posted by: spidey07
So are the realy pretty welds on high quality bicylce frames difficult to do? I would guess so being aluminium. They do looks like a neat stack of dimes, pushed over.

Thats how the normal bead looks like. For aluminum, you just have to have the right equipment.

 

[LS20]

some of the alloy (bicycle tubing) manufacturers claim to have alloys that strengthen after welding... (air-hardening alloys.. such as reynolds 853, true temper ox platinum, etc).. so supposedly the weld joints are stronger than the rest of the tubing

 

[J0hnny]

Originally posted by: dartworth

Originally posted by: FoBoT
no, the weld isn't stronger that the rest, anytime you have a joint, it is a flaw/weakness in the metal

negative...the filler metal is as strong or stronger...

Correct. As a pipeline engineer, I can attest to that.

 

[ScottMac]

Originally posted by: freebee
I just successfully soldered an entire 20 pin power supply connector by hand (including shrink wrap tubing). Each wire had to be done individually and matched by color!!!

Soldering is like welding for nerds.

In terms of "accomplishment" , maybe.

Welding essentially melts the pieces together with an additional bonding filler, soldering does not "bond" anything, there is no mixing of the components ...

FWIW

Scott

 

[jjones]

I used to weld pretty good in the old days - arc, gas, mig and tig; these days I'm better off using superglue. Of course my fav thing to do, which is not welding at all, was just using the cutting torch; lots of fun ripping through big chunks of metal.

 

[Demon-Xanth]

The biggest difference between soldering and welding is that soldering is a chemical bond while welding is a mechanical one. The molten solder forms a kind of amalgam with the copper/nickel/tin/etc.. and that is what holds. In welding, the material actually melts WITH the metal. If you took a solder joint and cut it in half, it would look very different from a welded joint cut in half.

 

[Bryophyte]

Originally posted by: jjones
I used to weld pretty good in the old days - arc, gas, mig and tig; these days I'm better off using superglue. Of course my fav thing to do, which is not welding at all, was just using the cutting torch; lots of fun ripping through big chunks of metal.

Yep, there's something about cutting metal with fire that appeals to the primitive part of the brain. I took classes in welding a few years ago. ARC, TIG, MIG, Gas, plasma cutter, it's all fun. I need to get a MIG and/or ARC setup. All I have now is Oxy-acetylene, and my tanks are empty.

 

[TitanDiddly]

Originally posted by: spidey07
So are the realy pretty welds on high quality bicylce frames difficult to do? I would guess so being aluminium. They do looks like a neat stack of dimes, pushed over.

Sort of. Many of them are automated. Automation makes a perfect weld every time. However, there is a good chance that you're not actually looking at the weld. Many frame manufacturers(like Cannondale) will make the weld, then go over it again with no filler metal (autogenous welding) to make it look real pretty. This can actually weaken the weld.

Skill in making a good weld is partly in the way your hold the torch, etc- but most of it is in how you set your machine. There are a dozen or so factors that all need to be just right to make a perfect weld. Voltage, current, gas flow rate, gas composition, polarity, HF start/run, waveform...

That's what will keep me in work. Those settings are usually determined by the welding engineer, and the welder just does the welding with minor tweaking if needed.