How and fast or slow and cold

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Whats the Best way to TIG weld? hot and fast (Aluminium is a given) or cold and slow?.  Help Zap.
Reply:The book sez about 10 inches per minute. Hope this helps.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:I really don't think there is a given rule to how fast or slow one has to go..Aluminum can be done slow even after its hot enough..All it takes is pedal finesse..Find your own speed and just go from there.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:I will go with hot and fast is preferable to slow and cold, but for most jobs it isn't critical. At the extremes, too cold and slow is a problem (huge HAZ, can be hard to maintain a puddle), but too hot and fast can be tough to control and makes it likely to get cold lap and voids.Hot and fast puts in less heat overall, so the HAZ will be reduced, distortion will be reduced, etc, relative to cold and slow.  Whatever speed you run at, there are plenty of things more important, such as satisfactory fusion into the base metal, proper weld size, etc.
Reply:Lincoln's procedure handbook  says faster being better for the same reasons Enlpck mentioned.
Reply:Most of the mechanized TIG I've been involved with runs between 3 and 6 inches per minute (ipm) travel speed.
Reply:I'm more of a hot and fast type of guy. On Al i travel at 15 IPM i don't like keeping the heat in Al since the heat treatable alloys weaken after welding due to over aging from the heat. --Gol'
Reply:on ALU it would vary more than most metals I bet.  Since its hard to weld al until it gets hot, your travel speed may have to be very slow for thew first inch or so, but once that heat spreads out you can move alot faster.  However, if youe welding thick to thin material it will vary again.Like Zap said, its all in the pedal.Have we all gone mad?
Reply:I agree with the logic of keeping the heat affected zone (HAZ) to a minimum, no matter what it is your welding.  Whether you weld fast or slow, you don't want to use more current than is needed to get the required penetration and joint fusion.  The microstructure and mechanical properties of the HAZ in most metals is generally degraded by things such as grain coarsening, segregation of phases, precipitation of compounds, growth of precipitates, and probably other bad stuff too.I think, in general, you may be able to reduce heat input, and still produce an equivalent weld, by traveling faster with a corresponding increase in current.  I think this has to do with a slower weld losing more heat to the surrounding metal through conduction, so the slower weld requires more overall heat input to penetrate the same as a faster/higher current weld.  If you crank up the heat and haul ***, the weld at any point is already solidified and you've moved on, before much heat is lost to conduction.  For two equal penetration welds (same depth), the faster weld should be narrower and have a narrower HAZ due to less heat conduction.If you had a mechanized TIG setup, you could develop a set of fast and slow welding parameters to produce two welds which were equal in penetration depth, and then calulate the heat inputs and compare.Heat input Joules/inch = (amps x volts x 60)/travel ipm
Reply:hot and fast , slow and cool. it's not as simple as one being better than the other. enlpck and pulser have covered the advantages of going fast. with aluminium and stainless i would agree completely- the lower the heat input the better as you can 'cook' the corrosion resistant properties out of stainless and heat softens aluminium.if your working with mild steel the differences will be minor in practicealloy steels can be a little different- depends what properties you're after in the finished item. 4130 for example is often welded with er70 (mild steel) for roll cages or tube frames. outright strength is not the goal- a ductile, fatigue resistant joint is. a higher heat input (welding slower) puts more heat into the joint (larger HAZ) but more importantly means the weld will take longer to cool resulter in a softer, less britle weldthings are never simple! as said by several others, the beauty of TIG is controllability- go at a comfortable speed, the weld is likely to better if you're not rushing/dawdling. there's quite a range of heat/speed that gives good results.the time when things get critical is doing coded work with, say duplex. especially if it has to pass corrosion tests
Reply:Originally Posted by pulserIf you crank up the heat and haul ***, the weld at any point is already solidified and you've moved on, before much heat is lost to conduction.
Reply:Let's look at this question from a diffrent angle..Say your doing round stuff with a positioner..If your doing a 20" diameter piece on the outside edge you'll be lucky to do 3" in one minute..On the other hand you can whip out 2" dia. pieces in no time flat..Granted the actuall material has alot to do with how fast you can go..And there are times when this that and another thing may "get in the way" (brackets/gussetts etc.) of you going fast even on flat stock..I dont think travel speed equalls squat..Unless your boss is never happy with anyones "built in pace".....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Originally Posted by zapsterI dont think travel speed equalls squat..Unless your boss is never happy with anyones "built in pace".....zap!
Reply:When pushing automated welding to faster speeds, whether it is TIG or MIG, you will start to get a surface defect called "humping".  It tends to be a series of raised humps, separated by depressions.  The humps look like surface tension has pulled the molten metal up, trying to form a ball.I have noticed several research papers in the last few years that are looking to characterize and solve the humping problem to allow faster travel speeds.  I think one of the benifits of new dual processes such as laser + MIG, is to suppress humping.http://www.mines.edu/~pmendez/Public...ers/1999OH.pdf