Welding in cold weather

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I just bought a craftsman 120v MIG gasless welder, I have to weld outside but I was reading a welding book and it said not to weld in weather below 40 degrees because it will be a weak weld.  Is that true?   Also, is there a difference between a Flux Cord ARC welder and a Flux Cord MIG welder? When I look around on the internet sometimes the articles don't have a Flux Cord MIG section, but they do have a Flux Cord ARC section.Last edited by NewbieMIG; 01-31-2005 at 05:32 PM.
Reply:I just bought a craftsman 120v MIG gasless welder, I have to weld outside but I was reading a welding book and it said not to weld in weather below 40 degrees because it will be a weak weld. Is that true?
Reply:Ok.. cold weather.... A little background:Low carbon steel (as most materials) has two major points on the stress-strain curve: The yeild point, and the ultimate tensile strength. Yeild is where the maetal distors (like taffy, sort of) taking a permanant change in shape. At temperature  goes down, the ability for the metal to yeild is lost, and instread the metal becomes brittle. The temperature at which the metal will not yeild is the Nul Ductility temp. For low carbon steels, this is in the ballpark of 50 degreesF. Preheat to at least this, and you won't have major issues. Warmer will give better welds with the small welder.
Reply:Thanks for the help....I'm off to practice...