Root, fill, cap question

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Noob here...been pretty successful in butt, lap and fillet joints with stick so far, but need to practice on root, fill and cap to a limited extent.  Due to the limitations of my machine I cannot weld any larger than 1/4" stock.  I realize that with something as thin as 3/16" and 1/4", bevels may not be needed in all cases, but I want to practice with them anyway.I'm using 3/32" 6013 and/or 7014 rods on sheet steel and have beveled some 1/4" stuff, gapped about 1/16".  Not much fill to do with the thin stuff, since about one layer fills the "V" and then a cap pretty much just sits on top .  The main question I have, is there a time one needs to wait after cleaning up the root and/or fill before adding additional stringers or weave...meaning should the welds cool down considerably, or just go ahead and add the fill stringers as soon as each of the previous welds' slag is cleaned?  If and when I can afford a larger welder (230) and can do thicker metal, I didn't know if cooling down any fill, etc.would be a factor.Last edited by shortfuse; 10-08-2012 at 11:15 PM.
Reply:I would like to ask you why? You seem to be wanting to do pipe type procedures, but don't have the amp capacity, nor are you using the right rod. If you want to an  open root on pipe, then get some pipe and some 6010. If you are wanting to do a structural root the get a backing plate and some 7018. Also, amps are cheap to come by. Keep you eye on CL for an ac/dc transformer welder. They can be had regularly for $125 for a really good machine.
Reply:Originally Posted by walkerI would like to ask you why? You seem to be wanting to do pipe type procedures, but don't have the amp capacity, nor are you using the right rod. If you want to an  open root on pipe, then get some pipe and some 6010. If you are wanting to do a structural root the get a backing plate and some 7018. Also, amps are cheap to come by. Keep you eye on CL for an ac/dc transformer welder. They can be had regularly for $125 for a really good machine.
Reply:it depends on the chemical properties of the material you're welding. Typically, for mild steel alloys, you'll have a maximum of 500*F interpass temperature. some alloys will require a MINIMUM preheat of 150*F+, again depending on the material you're welding. i agree with walker as well, 6010 & 7018 should be your weapons of choice here.
Reply:With all due respect to all, I don't want this question to get too specific as to type of welding or rods used...Rephrasing the question a bit...in GENERAL, say in a welding class or for a test, using mild steel, say 1/2" thick, after one lays down a root with the proper rod, can the next layer(s) of fill with the proper rod(s) be done while the previous layer is still D*MN hot!  or do they need to cool down to the touch? (I am reflecting on many educational and great pictures and videos on the forums from some very experienced welders of the root, fill and cap process)
Reply:2000_SS pointed out the 500 F interpass temp. Odds are it'll cool down to that point or below just from the time you spend cleaning between (Unless you're grinding till glowing). You can get an IR thermometer if you wanna be sure but I'de just have at it. Just tear it up afterwards to see how it worked out
Reply:Originally Posted by Snuffy2000_SS pointed out the 500 F interpass temp. Odds are it'll cool down to that point or below just from the time you spend cleaning between (Unless you're grinding till glowing). You can get an IR thermometer if you wanna be sure but I'de just have at it. Just tear it up afterwards to see how it worked out
Reply:It depends on what you are welding and in what position. Also every one welds a little different. When i weld plate i let it cool down and not get so hot.  on tube I throw the metal to it, the hotter the better ( it allows you to flush out really flat). then after I flush out a tube I will let it cool before I put in the cap. Just weld ,weld ,weld, till you find out what works for you. But if you are welding open root you need to be burning 5p+ and 7018 ,
Reply:Originally Posted by shortfuseNoob here...been pretty successful in butt, lap and fillet joints with stick so far, but need to practice on root, fill and cap to a limited extent.  Due to the limitations of my machine I cannot weld any larger than 1/4" stock.  I realize that with something as thin as 3/16" and 1/4", bevels may not be needed in all cases, but I want to practice with them anyway.I'm using 3/32" 6013 and/or 7014 rods on sheet steel and have beveled some 1/4" stuff, gapped about 1/16".  Not much fill to do with the thin stuff, since about one layer fills the "V" and then a cap pretty much just sits on top .  The main question I have, is there a time one needs to wait after cleaning up the root and/or fill before adding additional stringers or weave...meaning should the welds cool down considerably, or just go ahead and add the fill stringers as soon as each of the previous welds' slag is cleaned?  If and when I can afford a larger welder (230) and can do thicker metal, I didn't know if cooling down any fill, etc.would be a factor.
Reply:I weld a lot of carbon to stainless transition welds(different o.d.same I.d.) with inconel.We keep a eye on interpass temps for the purpose of maintaining a consistent weld profile.It's not a metelurgical issue it's a controlling your bead profile issue. If I didn't let it cool between passes my beads would narrow and sag on the bottom. This is orbital tig welding(gtaaw) but the principles apply across the board.
Reply:Originally Posted by hobohilton---------------------------------------------Answer - Think of this weld as a woman.... Myself, I always liked them "hot and fast"............... but again, every welder is different.Thanks,Hobo
Reply:I guess one thing that also triggered my OP question, is that on this forum and other places you see stacks of several passes on welding thick metal (sheet, pipe, anything).  If you make passes too fast, the darn metal is near red-hot and if you waited until it cooled down a lot between passes, then that's a lot of down-time and no $$ in the wallet.  If it's by the hour...great.  If by the job, not so great.  Once again, speaking as a noob.
Reply:where i work, we weld plates up to 3" thick, sometimes more. you MUST make multiple passes to fill up material that thick, especially when the joint is beveled on both sides. Typically, in my shop, any material over 1" in thickness will require some preheat. if it's P4 material, which is just another funky mild steel alloy basically, it must be 250*F before you can even strike an arc. We have "temp sticks" which are basically crayons that melt at a given temperature. that is how we monitor the materials temperature. you'd be surprised how much welding you can do even to a smaller pipe before it reaches 500*F. the parts cool quite rapidly and in winter months, we usually have torches blowing on them all day to maintain the minimum preheat, but the "pipes" we weld are actually plate that has been rolled, sometime 10' or more in diameter.
Reply:Originally Posted by shortfuseI guess one thing that also triggered my OP question, is that on this forum and other places you see stacks of several passes on welding thick metal (sheet, pipe, anything).  If you make passes too fast, the darn metal is near red-hot and if you waited until it cooled down a lot between passes, then that's a lot of down-time and no $$ in the wallet.  If it's by the hour...great.  If by the job, not so great.  Once again, speaking as a noob.