Tig Welding Steel and Controlling Heat Input

hey this is Jodi with welding tips and tricks' calm with another weekly video we're TIG welding today TIG welding cold rolled steel that's just like ten ten to ten twenty plain carbon steel cold rolled finished I'm going to sand it down anyway I'm going to be welding on shiny bright metal and there's a reason for that because we're going to be talking about heat input now I want to give credit where credit's due because Lincoln Electric put out a video very similar what I'm doing today a year or two ago and one of their instructors their school Carl hose very good instructor he did a really good job of breaking this down I just think maybe I've got a few things to add to it and hey that's how we all learn right we saw chip in and give our two cents worth so going to be welding lap joints today I'm going to be talking about heat input what effects heat input what you can do to affect heat input and some things you may not have considered so let's do it I clean these pieces of 11 gauge with us with a flap desks while I'm welding on clean shiny bright metal and part of the reason is so we can see the discoloration and the extent of the heat zone very well you could do it you can see it anyway on cold rolled steel but we'll just be able to tell exactly where the discoloration is with this all nice and clean I'm starting here the first one I'm going to run it at 80 amps I'm using this big old twenty six air-cooled torch but with a stubby gas lens on it and I'm using one sixteenth that's one point six millimeter filler wire and I'm going to use that throughout here just to keep everything the same so I'll take a few dry runs here and I've gotten hash marks on there at three inches and I'm starting in the middle so I don't get any effects of heating to end up and I don't get any effects of going to an end either now at 80 amps it takes this thing like nearly five seconds to puddle enough to where I can join it and get and get moving and that's a bit of a problem it's a problem on stainless steel actually and and some other metals it's not so much of a problem here if this this 80 amps will weld this this 11 gauge steel which is which is roughly 120 to 125 thousandths thick or three millimeters thick thick but you can see how slow it goes it's a very slow process a little too slow for for my tastes if I have you just had to weld something and you only had a little 90 amp inverter or something you could do it but it took a whole minute to go three inches here and that's just that's just too long decent-looking well but it just took it just took forever and you got I got a big heat mark they're going out to the end and now we're going to run one at 120 amps everything's the same same filler wire and all that kind of stuff same tungsten size I'm using a 3/32 which is 2.4 millimeter 2% lanthanide electrode and see I get a puddle right away you don't have to wait to establish a puddle and I can get moving and something a lot more reasonable plus you can see that the puddle is going down into the root of the joint and going all the way up to the corner which is just kind of a matter of preference I like to fill in fill it Wells like this on sheet metal all the way up to the corner I've just seen a lot of them fail that haven't in the industries that I've worked in now you can see right away that the extent of this coloration is less so I've got less heat input here with 120 that I did using only 80 amps so right away we can see that amperage isn't the only thing that affects that affects heat input now there is somebody asked me just the other day about what about this 1 amp per 1000s rule does that hold true on up into 3/8 and 1/2 inch thickness well it doesn't it my my opinion is the cutoff is about 160 this is a big chunk of metal here at some 4140 high-strength steel and I welded this thing at 160 amps and in fact found out that going much higher on the amperage was detrimental because it diluted too much of the base metal into the filler metal I was using er 70s to filler metal that was the spec on this job and I read just ran multiple passes 160 amps to get the to get the required fill it size and that worked out well for me but in answer to the question again it's a good rule of thumb for sheet metal up to you know easily up to an eighth of an inch thick 101 amp per 1000 sore or 40 amps per 1 millimeter would be a good rule of thumb but it's just a starting starting point and there is a cut-off and that cutoff for me is about 160 amps now I'm going to weld one at 140 amps I got to get everything just right and get ready to put that filler rod in there I'm set the machine at 140 and going full pedal so I'm moving on out here I've even sped it up with a film a little bit more but this only took me 25 seconds to weld the three inches that's a that's a far cry from the whole minute it took on on 80 amps and you can see that I've got a little bit less discoloration a little bit less heat zone or a heat discolored zone then either one of the other two so there's that there's a point at which there'll be a cut-off but generally speaking travel speed is the biggest the biggest factor you just got to be able to keep up with it and what if I use a Lee Weyer technique here and just fly I don't even put any I don't even dip it I'm just running over that 1/16 wire just about as quick as I can at 160 amps you could actually go much hotter and much quicker than this in fact this is the way a lot of automated applications are are done in industry like tube mills welding on same tubing is done in in the feet per minute not inches per minute range so it just doesn't provide the kind of look that that people have come to want as far as the stacked dimes look but it is a quick way of getting something done you can see the heat zone is very narrow at 160 amps because I picked up the travel speed so much this is just I just did this just to show 160 amps versus 80 amps this has got a much narrower heat zone than the 80 amp or the hunter or the other two that I will that in fact I mean I think it's the way to do it I'm just doing this for the purposes of an instructional video just to talk about heat input and how a travel speed really really is the big player the formula for heat input goes something like this volts times amps times 60 and that would be in all in parentheses you do that if you do that equation first divided by travel speed looks something like this so big deal right have I lost you don't worry we're not going to go deep into that stuff just want to talk about things that affect heat input voltage affects heat input and that's your arc length amperage that's your current and you control that with your foot pedal and/or the Machine setting so you got voltage and amperage and in travel speed travel speeds a big one probably the the biggest one you can really reduce heat input by increasing travel speed you can increase heat input by slowing the travel speed down a good example of this is is holding too long an arc when you hold too long in our contiguous and you increase the voltage you don't pinpoint the heat takes a little bit longer to melt everything things don't kind of go together like they should because you're Fanning the heat out there you're not directing the heat so you're slowing travel speed down and you're increasing voltage and you're you know doing all kind of things the rod is balling up and blobbing in there and you get all you get oxidized looking surface because the metal is still terrifically hot while the argon leaves it and just not what you're looking for from TIG weld contrast that with same amperage here I'm still using 100 amps here I just tightened up the arc now everything is going much better and much quicker and it's going more like TIG welding should and I'm putting less heat into the part which is usually a good thing now sometimes stuff is in your way and that slows your travel speed down or you're out of position vertical uphill or overhead or something round that you just have trouble getting around that's going to slow your travel speed so let's set up a vertical uphill lap joint here I'm going to run this at 110 amps now doing a joint like this it's kind of hard to find a place to prop now I'm this is a shameless plug for my TIG finger here but stick with me I think you'll you'll enjoy what you see you can see it's got more layers on one side than it does on the other so that the air at the side that you're going to prop on that's the one you want to choose to use the one with more layers on right here and also it's long enough that you can double it over and get it even twice the amount of protection there and so that's what I'm going to do here I'm going to rest it right against that edge I'm just going to slide it right up the joint as I will this this three inch run here and four vertical joints I have found even though this is a big old 26 torch I've found turning it upside down like that it's a lot more comfortable for me and I'm a lot less tired at the end of the day if I have to do this kind of thing but 110 amps is about right for a vertical joint here 120 I would I would have a hard time keeping up with that so you got to consider that when you're out of position as far as the amperage that you that you select you're going to need a little bit less amperage to get the weld done just you really can only handle a certain amount of amperage because you can't keep up with it because you can't keep up with the travel speed because it's a little awkward it's not like laying it flat on the bench now 110 amps is adequate for this vertical uphill you can watch the front of that puddle you can see it's sinking into the root of the joint it's consuming the whole corner there on the 11 gauge so it's about right but you can also see how hot that that edge gets where I'm propping because it's red-hot right next to me and I'm just following that thing up and I can hang there all day long like this whereas otherwise I'd probably be screaming right now and throwing the torch across the room or something like that so slinging the glove off or something like that I don't even have to worry about not hanging around getting good post flow because not even warm yet so just really helps on joints like this you see that huge heat mark there another reason for that it took me 41 seconds to run make that that 3-inch run but another reason for that big heat discolored areas I'm not laying on the bench and I don't have any quench effect from it laying on the bench so it's out in Free State like that it's going to get hotter more heat input and also it being out of position but it still welded okay there's a compared to the 120 amp welded on the bench 110 amps going vertical because it was slower bigger heat zone also on joints like this that are round and out of position like this I'm using a scratch start air cooled rig here you can use travel speed to your advantage there because you're going to start off you're only going to have one amperage here you don't have you don't have the luxury of adjusting it like with a foot pedal or whatever so you start off a little bit slow heat builds up and then you increase your travel speed to compensate because you've only got one amperage and we know already that travel speeds a big player so here you're just speeding up and slowing down using travel speed to control your Heat it's like I say this is a scratch start air cooled rig no amperage control just is what it is so you have to use travel speed things get too hot you can speed up and it really helps a lot and that's travel speed is the big factor in controlling heat input now don't want to make anybody afraid of heat input or like it's a bad thing it's just something to be concerned with because it can affect the properties of the weld in the metal now I'm welding cold rolled steel here on this bench so it's going to affect it less than most things it will have a somewhat of a softening effect on it because the the grains in that cold rolled metal will recrystallize in a certain area and soften up and be basically in annealed area and you'll lose the benefit of the cold working also when you start welding on things like this big chunk of 4140 or high-strength steel with higher carbon and things like that now heat input tends to have a bigger effect and that's why you you need to prove out a welding procedure that's the need for welding procedures because you got to know that you're you're controlling he didn't put within a certain set of parameters and the only way to do that is to run tests and and and whatnot so also on aluminum heat input affects the properties of the metal a lot typically when you overheat aluminum you're going to basically take it back to its annealed stage which is the softest stage in a certain area right around the weld so that's why a lot of people will set up pulse parameters for aluminum to limit the heat input just a quick reminder that I've got the 2013 DVD set available now weld monger store calm it's a four-disc set every video that I posted in 2013 took four discs to get it all on got a nice little menu on the back so you can see what exactly is on each disk that's available at weld monger store.com also you saw me using that tick finger quite a bit in this video I'd love for you to grab one if you think this is something that would help you by all means try one out I get zero emails of people that are disappointed that they bought to take fingers so see you next week

Channel: weldingtipsandtricks

Views: 435,099

Rating: 4.9348712 out of 5

Keywords: tig welding, tig welding steel, tig welding tips, tig welding techniques, heat input, welding steel, tig weld, tig weld a lap joint, tig welding vertical, tig welding tubing, how to tig weld, Gas Tungsten Arc Welding

Id: DmVCLi6cxok

Length: 12min 53sec (773 seconds)

Published: Tue Apr 01 2014