Un-weldable steel?

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I went to a scrapper last weekend and bought some steel pipe to make a hinged pipe "collar". Anyway, when I was welding (cobbling) this thing together I dropped it and the hinge I just welded on popped off. Tonight I used a screwdriver to pop it apart. What type of steel won't weld to mild. I used my Lincoln 175 with mig wire and gas set at D-4.5 whatever that equates to.  Any ideas?Lincoln 175Monkey Wards 230v.  Stick
Reply:Iron pipe??? I made that mistake once."Where's Stick man????????" - 7A749"SHHHHHH!! I sent him over to snag that MIC-4 while tbone wasn't looking!" - duaneb55"I have bought a few of Tbone's things unlike Stick-Man who helps himself" - TozziWelding"Stick-man"
Reply:I have no idea what it is. The welds just peeled off. I'll try the grinder test on it and see what color the Sparks are.
Reply:Free-machining (leaded) steel (12L13, 12L14, e.g.)looks nice and is excellent to machine for finished parts where welding is not planned, but it is very difficult to weld, since it has a small percentage of lead. (.15-.35 lead and similar amounts of sulfur)  This causes difficulty since the lead has a lower melting temperature than ordinary mild steel. The OP's welds look almost like cast iron was used.Miller Millermatic 252Miller Syncrowave 200Liincoln AC-DC 225Victor O-A Set
Reply:High carbon steel will crack as the weld cools too.
Reply:This stuff cut easily with the cut off wheel with no cracking.  When I put it in the vice it bent easily.  I'll just have to get a different piece and start over. Thanks y'all.
Reply:Is it magnetic?
Reply:That's why it's not good to use scrap you don't know what it is.
Reply:Which "steels" don't weld good?Cheap Chinese pipe, bed frames, and common rebar.Seeing how it long n round with large hole in middle, I suspect it is cheap Chinese steel pipe.They build better structures from bamboo than some of their "steel".Last edited by wornoutoldwelder; 03-19-2015 at 01:09 AM.
Reply:Rust inside makes me think its old boiler tubing.Old stove grates wont weld because the surface is loaded with carbon.Try an arc on the inside with your stick welder.I gave up using scrap because the finished item looks like scrap.I buy new steel now.We grow too soon old and too late smart.
Reply:Originally Posted by farmer37Rust inside makes me think its old boiler tubing.Old stove grates wont weld because the surface is loaded with carbon.Try an arc on the inside with your stick welder.I gave up using scrap because the finished item looks like scrap.I buy new steel now.We grow too soon old and too late smart.
Reply:Originally Posted by wornoutoldwelderI'ma white headed old retired Navy destroyer and nuc submarine steam propulsion engineer and a former Hartford Steam Boiler Co Boiler Inspector, and the ONE thing I enjoyed most about my former job as a boiler inspector was the fact I was mostly a welded repair inspector where welded repairs of old corroded boiler tubes was as routine as my daily turd after breakfast....From pinholes, to replacing whole sections of membrane water wall tubes, I saw it daily, and those welders made it look easy.I look at things different than you. I discovered some pretty sound people in the scrapyard, and lots of quality steel. I only need to brush off as much rust as necessary to make a decent bond with both...I was lucky and got smart early because I saw then, I didn't want to die old and stupid.If you want to challenge a young man today, give him what's left of yesterday and insist he fabricate his tomorrow from it....Eventually he will haunt only the scrapyards and perhaps dig even you up and make you live forever too....."Ashes to ashes-dust to dust, where the best of the best is just below the rust"
Reply:Originally Posted by wornoutoldwelderI'ma white headed old retired Navy destroyer and nuc submarine steam propulsion engineer and a former Hartford Steam Boiler Co Boiler Inspector, and the ONE thing I enjoyed most about my former job as a boiler inspector was the fact I was mostly a welded repair inspector where welded repairs of old corroded boiler tubes was as routine as my daily turd after breakfast....From pinholes, to replacing whole sections of membrane water wall tubes, I saw it daily, and those welders made it look easy.I look at things different than you. I discovered some pretty sound people in the scrapyard, and lots of quality steel. I only need to brush off as much rust as necessary to make a decent bond with both...I was lucky and got smart early because I saw then, I didn't want to die old and stupid.If you want to challenge a young man today, give him what's left of yesterday and insist he fabricate his tomorrow from it....Eventually he will haunt only the scrapyards and perhaps dig even you up and make you live forever too....."Ashes to ashes-dust to dust, where the best of the best is just below the rust"
Reply:Sorry boys but I started welding in 1955.I remember scrap yards wanting 20 cents per pound for scrap.The last 2 posts are BS,wordy but still BS.Fellow stopped at a yard asking to buy lead.Woman said we dont sell.just buy.Most yards wont sell small amounts.I have bought new steel in a scrap yard but that yard is gone now.The yard had a rail road siding and cut scrap up as fast as it came in.I used to buy new scrap from a steel yard but they stopped that.Easier to fill a dumpster and sell it.
Reply:Originally Posted by farmer37Sorry boys but I started welding in 1955.I remember scrap yards wanting 20 cents per pound for scrap.The last 2 posts are BS,wordy but still BS.Fellow stopped at a yard asking to buy lead.Woman said we dont sell.just buy.Most yards wont sell small amounts.I have bought new steel in a scrap yard but that yard is gone now.The yard had a rail road siding and cut scrap up as fast as it came in.I used to buy new scrap from a steel yard but they stopped that.Easier to fill a dumpster and sell it.
Reply:Weld metal deposit looks like aluminum.
Reply:I figured out that it was operator head space. I had my mig set for flux core instead of solid core.  It welded great after i switched it.Lincoln 175Monkey Wards 230v.  Stick
Reply:HotRodTroyKudos: for openingly acknowledge your private oversight  . . .Which wire -  'who's on first' - DCEP/DCEN? Self-effacing candidness is expected - amongst career welders.Post your successes - but oversights are equally important.OPUS
Reply:sometimes the best way we learn is through our oversights and or mistakes....Of all the things I lost I miss my mind the most...I know just enough about everything to be dangerous......You cant cure stupid..only kill it...
Reply:When I looked at the pictures I said that the weld looks way too cold, No heat in the job. Then he admits that he had it on electrode negative,it all makes sence.
Reply:Imagine how i felt when i noticed that. Its not fun running out of gas.Lincoln 175Monkey Wards 230v.  Stick
Reply:Hey Troy, this is what forums are about, nobody is perfect, we all overlook the most obvious thing sometimes.
Reply:Agreed.Lincoln 175Monkey Wards 230v.  Stick
Reply:I just welded up something yesterday using some rebar that had been submerged in saltwater for a long time (it had been the frame of a crab trap) and trying to weld that rebar was MURDER, even with 6011.
Reply:I'm surprised that would even stick together and not just fall apart.Lincoln 175Monkey Wards 230v.  Stick