not sure about the mig making the metal brittle. But gas is a lot nicer weld on sheetmetal.

 

Never heard of it making metal brittle either. If you hook the bottles up to a MIG it provides a little cleaner weld and allows you to weld a thinner metal. I have heard that alot of the big automakers recomend (but don't require) mig welding for alot of their repairs. Not sure why but they have their reasons.

Tim Springer
1980 CJ7

 

/wwwthreads_images/icons/smile.gif Been there....done both. Actually the guy is right on one hand, you CAN weld flimsier stuff with gas and rod. However, the problem with gas is that before you are finished the whole darn CITY has been warmed up. That is the heat has spread widely, and now you have colatteral damage to deal with and you may have to do some shrinking to get it to look right. MIG welders can sort of be used with a spot-stop-spot-stop technique to weld thin stuff without getting everything too hot. You let go of the trigger when the heated spot is the size of a nickle as someone previously ponted out. So on balance, there's a place for both. I'm one heck of a gas welder and header-builder, but I really appreciate my MillerMatic 35 wire machine for a lot of the touchy stuff too./wwwthreads_images/icons/crazy.gif

CJDave
I never believe any statistics unless my moonguys /wwwthreads_images/icons/crazy.gif/wwwthreads_images/icons/wink.gif made 'em up themselves.

 

HAha good point Dave... its a lot tougher to get a good weld (flat and smooth) with a gas rig. But I prefer it for body work to using a mig. Then again, I prefer lead to bondo so...

 

I have welded with mig, tig, stick, and gas. If I was building a high dollar street rod gas welding would be the way to go. For welding floor boards and general body work on modern alloy sheetmetal (mid '70 and up) I would use the mig. Your best bet is to buy a good miller,lincoln, or hobart welder prefferably 220 volt, if your short of money get the welder first and run flux core, then by the bottle & regulator later. flux core is nice for welding outdoors, but running on the bottle is a lot cleaner when your indoors and you can lay down some great looking welds that are all most too pretty to paint.
good luck, jjc

 

I heard that mig welding adds a lot of nitrogen to the weld and connected metals
which will cause brittleness (is that a word?) the same way chroming stuff does.
High nitrogen was a factor in the Titanics sinking as well. I do not know much about metallurgy
but this is what I heard.
Gibby

 

not sure how it would add nitrogen more than say.. a flux core wire feed or stick. Migs use Argon/CO2 gas mixes for steel. Be interesting to find out.

 

What the h*ll kinda vocational school are you going to?
Sorry but probally less tha 1/2 of 1% of any body shop does any welding with a torch. CJ Dave is right on!!!!!!!........You will warp the crap out of any thin guage sheetmetal doing it that way. Old timers can do it (& I mean old....sorry Dave/wwwthreads_images/icons/smile.gif) but you don't see too many "blacksmiths" anymore either. I have been blessed to get to teach (adult ed welding) with some of the best there ever were with some "neat" skills. We all know heat expands metal but have you ever seen a man take a dented , wrinkled , TRASHED piece of sheetmetal and with a torch , bucket of water and a shoprag make it glass smooth? Thats an ART and a real bodyman....not too many of them left.
Had a pipefitter come in for a demonstration and ended showing me how good he could gas weld alum. Even in guided bend testing it held up every bit as good as my tig welded samples.(I watched him do it , he showed me how and my samples would'nt even start to bend when they broke when I used a torch).
I could go on and on.......sorry.
Wire weld your sheetmetal in. It'll work great , minimal warpage & if you did even a half *ss job it will be stronger than the base metal.
Wire is all any bodyshop uses anymore.
Also I don't know about nitrogen making the metal brittle (never heard of this on mild steel in any degree) but I do know hydrogen can be a problem (which causes porosity which can weaken and harden a weld) which is why most structural welding is done with 7018.(70K ten. strength and low hydrogen)
Sorry to be so long winded/wwwthreads_images/icons/smile.gif

Wider is better but taller is cooler!

 

Gibby -
Was that the nitrogen iceberg or the nitrogen navigator or the ......??????
Seriously, you have my full and undivided.
sln

 

Slnewcomb, the Titanic was made of extremely brittle steel which caused it to shatter in the
affected area at impact rather than bend and absorb some of the force. This caused a huge gash
where it hit the berg. If the material was as ductile as it should have been the ship might not have
sunk or at the very least would have taken days instead of hours to sink.
Also, I may be confused as to whether it was nitrogen or hydrogen that embrittles steel. Doh!
Gibby

 

Re: another question for the welding experts - Another point

Not getting involved in the welding conversation. I can't even do super glue very well.
But would like to make an observation about your comment concerning the oldtimer experts. I was fortunate enough to grow up around a 3rd generation real honest to goodness blacksmith shop. Last one left in Texas. Big write up in the paper when it finally closed down - in the 60's I think, but that's not the reason for this note. The guy who ran that shop could build anything from a Sherman tank to an ice cream cone with a forge, big 'ol hammer, an anvil and a bucket of water, however. A real master.
ANYWAY, to the point. Some of us have been fortunate enough to see a few real masters in our life time, people who are artists at what they do. I'm not talking about professionals. Lots of them around - well maybe not lots, but several. I'm talking about the artists who are a big step above the professionals. The very few I have been priviledged to see have been rather low key, don't brag, just do whatever it is that they do, and do it to perfection without seeming to try at all. They take pride in their work without showing it and without giving the impression that they are even aware of their artistry.
Those of you who have seen an artist like this know what I am talking about. Those who haven't, keep your eyes open. Maybe you will be lucky enough to see one. They are rare.

Doug '97 TJ
Creator of the CBrack
My Web Site

 

Re: another question for the welding experts - Another point

/wwwthreads_images/icons/smile.gif Wow! Nice post Doug. You are absolutely right; and I do secretly worry that so many old-world skills are disappearing. I'm just old enough to remember real blacksmith work, and I always admired the way those guys could work steel. I have watched (and done) sheet shrinking with a torch, water, and an old towell. The old blacksmith shop where we were had an acetylene generator right there in the shop. They tossed a chunk of carbide in water and away it went. When the "end times" get here we will be running our Jeeps that way. In france in WWII all the taxicabs had acetylene bottles on the roof./wwwthreads_images/icons/crazy.gif So save up those chunks of carbide and learn those old world skills. If Gore is elected the crap will come down soon after./wwwthreads_images/icons/crazy.gif

CJDave
I never believe any statistics unless my moonguys /wwwthreads_images/icons/crazy.gif/wwwthreads_images/icons/wink.gif made 'em up themselves.

 

Yea, the titanic had brittle steel because it had a high sulfur content. Learned that in History class a few years ago.

Robert87yj/wwwthreads_images/icons/tongue.gif
engine rebuild w/4.0 head done, now for the MPI

 

Re: another question for the welding experts - Another point

whew..... I sure don't consider myself any artist.... And, surely no expert. In recent years, I've wanted to try a wire-feed, but, so far, I haven't done it.
Back in the 50's, I was 'turnin' wrenches (and sweepin' floors/cleaning parts) at a little shop that was next-door to a body shop. There was a guy that shared some of our shop-space. I spent a lot of time watching him massage metal. He used a little lead filler, occassionally.... But, mostly, he just straightened panels out. In the early 60's, I bought a gas outfit, which I still use. I started practicing, and one thing has lead to another. First, I learned to straighten and shrink, and maybe use a little filler. I went through a period when I wanted to learn to use lead. Then, I worked towards no filler at all. Then, I worked towards both the 'front-side' and 'back-side' both looking flawless. Along the way, I taught myself to install 'patch-panels', with the welding invisible both on the front and the back. I still find it difficult to do very large, flat, panels. I'm not very good at floor-panel replacement. I live in an area where I haven't had to do many. It is for floor panels, that I believe I would like to try a wire-welder. I once installed a firewall in a 33 Ford, that had been torched-out. Putting it back in, was a lot like installing floor panels. A hot-rodder friend, who had seen the car when the firewall was out, looked over my work, and said that he couldn't find my welds, either inside, or out. That, is the sort of finished product, that I strive for.
Sorry, I don't mean to bore you. My point is, hopefully, you can DO this stuff, if you really want to. It might take a little time, and a lot of practice, but you CAN do it. To anyone starting out, I'd recommend a wire-feed. But, if you are going to massage panels, I don't see how you can avoid having a gas outfit, also. For 'fixit' stuff on Jeeps, chassis work, etc, I have been using a stick welder. But, I can certainly see how a wire-feed can replace my old stick welder. For my hot rods, where aesthetics are 'all-important', I have been paying a true artist, to do the heli-arc welding.

bob

 

Gibby-
Hydrogen embrittlement occurs in very high alloy steels and then only at elevated temperatures and pressures. None of this is descriptive of the steels at the time of the Titanic. Also, there is no huge gash in the hull. Ground penetrating radar and sonar imaging have shown that to be another one of the myths that simply had no basis in fact. There are, IIRC, a total of seven holes in the starboard side of the hull that are the result of plates having been ripped off of the framing members. The total number of holes exceeded the number of watertight compartments that could be filled and have the ship remain afloat. This bad news was known to the ship's engineer lesss than 10 minutes after the collision with the 'berg.

There was nothing wrong with the steel in the Titanic. It was as good as there was in it's day. There are those who say today that this or that was wrong but this all is judgement from the view of today's fantastic array of steel choices. Nobody now, or then, had a steel that would have stood the test the 'berg gave to the ship, her masters or her designers.

My favorite Titanic myth was perpetuated for several decades (into the '70's) and resulted in some earlier desires to search for the wreckage being scrapped. This was the myth that the ship was so modern and streamlined that it would gain speed all the way to the bottom and hit so hard and fast point-on, that it would either explode on imact if it rock and disintigrate into a bazillion pieces or if it hit mud (the preponderant majority held this view) then it would bury itself many hundreds of feet deep below the ocean floor and therefore could never be found.

As an extra note in this thread that has an awful lot to do with my favorite form of transportation, that being Jeeps, the recent discoveries as to the nature of the holes in the starboard side confirm one more thing: the Titanic almost missed the 'berg. Just a few more feet and we would never have had one of the best movies of all time.
sln

 

/wwwthreads_images/icons/smile.gif An interesting note......as steel shipbuilding and marine design was gradually overtaken by metallurgy (in Titanic's day, the building had gotten ahead of metallurgy), a tremendous amount of time and effort was devoted to coming up with the "ideal" hull plate. The ideal plate would bend, stretch, dimple, ripple, fold, even tear. Everything EXCEPT crack. There is substantial evidence that the plates in Titanic DID crack open, and a slug of steel out of a rivit hole which a Titanic workman's son had as a desk paper weight also tested too brittle to bend, crumple, or stretch. It just gets down to this, folks...if it floats and is made of steel, it can sink....period./wwwthreads_images/icons/crazy.gif

CJDave
I never believe any statistics unless my moonguys /wwwthreads_images/icons/crazy.gif/wwwthreads_images/icons/wink.gif made 'em up themselves.

 

Re: another question for the welding experts - Another point

Good point on checking out the street rod guys. They are always trying to resurrect some old rusted out junk sheet metal to make into show quality stuff. That is the guys that want a steel body and not fiberglass. They are probably a good resource...CJDave has their formula, spot-stop etc, water rag..

 

Re: another question for the welding experts - Another point

I read in a reputable science mag, (I can't remember the name now, probably popular science etc...) that the steel used in the Titanic was very high Carbon steel. Carbon content is generally related to the malability of the steel. Higher carbon, a more brittle part; and vicea-versa. They actually stressed a piece of the Titanic's bulkheads and a comperable piece made to todays standards of steel, and where one bent and bowed, the other cracked clean in two, without a hint of bending.
You can see this in knife blades. A quality blade will break when stressed to the same extremes that would render a poor quality blade bent.
Just what I'd heard...

Florida Mud CJ-5
'77 RB304, t-150 D20 4" 35" swampers