Winter welding

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Hi,I would like to known what are the impact of the outdoor temperature on welding? I'll probably weld in temperature bellow -20 degrees Celsius.All the best,Samuel
Reply:THere are concerns with a number of materials at these temps.Many materials (steels, in particular ) have ductile to brittle transition temperatures in the ballpark of freezing (32F, 0C). Below the transition temperature (which is actually a range where the material loses ductility and becomes more brittle fairly abruptly), the material is much more likely to crack from such things as impact, weld shrinkage, etc. In addition, the weld metal will be chilled more quickly at lower temperatures, reducing its ductility, as well, and will shrink more, relative to the base metal. Low carbon steel should be 50degF (10 degC) minimum before welding to minimize the issues with ductility. Thicker sections should be at higher temp (200F, 90C) is not uncommon for thick sections, cold environment or not  (many of the procedures I work with are 200F or 300F for a number or reasons, including minimizing distortion, minimizing cracking risk, and to eliminate the need for postweld heat treat/stress relieving)Heating does not need to be the whole part, but the heat should be sufficiently far from the weld area to keep the cooling rate moderate, and to be sure that there is sufficient ductile material to avoid cracking. A rule I have worked with is that preheat must be maintained to a distance from the weld that is the thickness of the base metal plus four inches. Not the only rule. More heating may be needed if you are losing heat fast, or if uneven preheat may cause distortion, etc.I would also suggest using electrodes that are rated for lower temp applications (such as E7018-1 rather than E7018). Look at the specs and note the temperature that the Chapy test is specified at.
Reply:If you are doing code work, the codes address this issue. Enplck covered the fundamaentals quite well.
Reply:Many thanks for your answer...Sam
Reply:Pre-heatttttttt
Reply:in  the  montana coal  mines  in  winter  i  have  seen  35  below  .  we  team  up  1 person  pre heat  were  the second  welder  did  his  thing  .no  this  was  not  code  work . just  to  keep  the  dragline   swing  and  hope  it  will  warm  up  soon
Reply:enlpck hit some important high points. Generally speaking when the base material temperature is 32 degrees 0 degrees [C] (actual metal not ambient temp) it should be preheated to a minimum of  70 degrees {20 degrees C}. Then during the spring and fall and early mornings heat to remove the moisture from the metal (sweat it). But during winter temperatures definitly use your pre-heat.Weldor/ Certified Inspector
Reply:I welded up a sleigh hitch with 7018-1-H4 at -20 a while back with no issues. Non critical job and certainly not code.If your doing code work like was explained already, you'll want to use pre heat.JasonLincoln Idealarc 250 stick/tigThermal Dynamics Cutmaster 52Miller Bobcat 250Torchmate CNC tableThermal Arc Hefty 2Ironworkers Local 720
Reply:After it's welded won't the rapid cooling, caused by the cold, cause problems?
Reply:Originally Posted by CWI_98enlpck hit some important high points. Generally speaking when the base material temperature is 32 degrees 0 degrees [C] (actual metal not ambient temp) it should be preheated to a minimum of  70 degrees {20 degrees C}. Then during the spring and fall and early mornings heat to remove the moisture from the metal (sweat it). But during winter temperatures definitly use your pre-heat.
Reply:Originally Posted by driftstarAfter it's welded won't the rapid cooling, caused by the cold, cause problems?
Reply:Yeah.....like WelderBC said pre-heat, an you might want to through some heat on ever it is your working on