View Full Version : Chilled welds
03-03-2009, 09:32 AM
Ever notice how when it is real cold outside, your welds look like crap? You can take a torch and heat it up to say, around 150 degrees before lighting a arc and it welds so pretty again tho..
Is it the SHOCK of the metal expanding rapidly? It does promote embrittlement I think.
03-03-2009, 10:09 AM
Pre-heating is usually a good idea on anything heavier than light sheet metal when using stick or MIG. Thermal shock can indeed cause several undesirable conditions that can easily be avoided by a bit of pre-heat and the heavier the mass the more important this becomes. Even the little under powered 110 volt MIG welders can be used to weld much heavier stock than normally thought if sufficient pre-heat is used. What are you using? Stick? MIG?
03-03-2009, 10:50 AM
What are you using? Stick? MIG?
Yes. I use welder of situation choice. Got all here. Fixing to trade the 80s Lincoln Mig for a Miller piggyback unit to sit on top of my synchrowave 200 so I can weld thicker steel with it.. I'll have to decipher that darned control plug at that time.
I enjoy tig welding the most. Mig is the fastest, Stick is still the heavyweight holder I trust. I remember when I bought that lil Lincoln, welded a trailer together, first thing.. I was used to industrial Mig's with 200amp output if needed.. well I busted two of the sixty or so welds on that trailer with a hammer.. I was dumbfounded.. went over all of them with a stick weld real hot. NOT enough heat for sure to weld structural welds. THE newer migs with CC/CV do much better, but still no industrial job.. wire.. ER70s.. most the time the supply sells you "easy grind" wire..
Never use that crap for anything you want to stay welded other than sheetmetal.
It was 20 when I got up. Sheesh.. I am in the middle of three projects here.. I shoved the F1 outside for the moment. Nothing is paying cash.
03-03-2009, 11:35 AM
That's what I was talking about with the pre-heat for the little 110 machines. Most any thickness of steel can be welded just fine with those little 110 outfits if it is pre-heated to about 400 deg or so (just too hot to touch with your bare hand) if you mind the duty cycle. For instance if someone just starts welding cold 1/4" angle with a 110 MIG and .023 wire they will just be asking for trouble but heat the joint with a torch first and it will make a perfectly sound weld.
That damned "Easy grind" wire should, IMO, be illegal :mad: because it is junk except for the auto body work it is meant for. The problem is that once it is loaded up on a welder (or someone just don't know any better) it is all too often then used for welding everything even though it is sub-standard strength and can lead to weld failure in a structural joint. "Easy grind" is an accident looking for a place to happen!
03-03-2009, 12:27 PM
Nadine: A 52 fleetline chevy. When the video gets to the clip job.. IT appears to be a mig weld, not Z-cut, nor tuliped out like I do, then hammer formed together.. but cut straight across. I'd bet the last hundred in my wallet it's easy grind, from a body shop.. Most the car was shoddily done.. upholstery was the only professional part of the car. I traded for the car, swapped the car off.
When I saw that I paled, then I noticed the front sheetmetal was not bolted down. Meaning a run to 100mph could wrap it all over the windshield. IT was bolted to the firewall at the fenders and floating in the front.
The newer car frames, the TransAm Clip that was in the Studebaker truck I loved so much, it is about a 14 ga metal frame. I got under it and it was Z-cut.. but welded with a mig and beads here and there.. Considering what the rest of the GM frame factory welds looked like?? well.. I ground it all down and took some small 6011 (mild steel all purpose) rods and got a good weld on it.
I had that truck to 100mph several times before I looked under it. I rode my baby girl in it, hauled a harley, some blocks for my house.
Main thing to note about structural welds, if you didn't do it, look at it real close.. If it is a 79 or newer subframe and has any rust that is flaky.. run away.. There ain't enough to weld.
You should see my brothers rebuilt Xterra.. I think that guy who did that is a meth head thou.