Cast Iron cut and weld

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I got  skid of stuff.  These are some kind of heat exchanger parts.  I have to cut out the old separators and weld in new ones  at the specified location.16 covers total, 8 of each
Reply:What process are you going to use to weld these?  Preheat?Will be interested to see finished product, Fred.
Reply:A little pre heat to get the moisture out.I cut the rib out with a hypertherm 600I cleaned it up with a 4.5" grinder then  heated it up to  400*f  or so.  I welded the new ribs in with Allstate something.  Esab NI55 is what it really is at 60 amps for 3/32 rod DCEP.
Reply:Measured and marked.    I ground off the bark, heated em up and welded away.   the machine of choice today is Lincoln V350 on stick smooth.  Hot start straight up, arc force around +8.
Reply:For this piece, I tried the plasma.  Not a lot of room for the gun, so I tried arc air with not much luck.  350 amps and I still could not cut it with one pass.   I then scored the cast with a cut off wheel and whacked it with a hammer.   Then I had to clean it up with a grinder.This one was cut with plasma or arc air.Pre heated to over 400*f then welded with 60 amps like the last one.The first one took an hour and fifteen, the second one took longerEach one used 1/2 lb of cast rod at about $20.00 a pound.David
Reply:Man, those look like a real challenge as a production job. Hard to just crank 'em out.Good luck with it.  Have they done any like this before?,  Or are you the experiment.?
Reply:I have done a couple before.  This time there are 8 of each.  David
Reply:I'm thinking 400F is a bit low for preheat on cast iron if you want to work it 'hot'.Lincoln suggests 500-1200F preheat (but not over 1400F, as that is where other metallurgical changes occur with cast iron) and make sure to cool s-l-o-w-l-y (as you probably know  ).And (obviously) make sure to preheat those new 'ribs' as well.  (ribs are steel? )  The best laid schemes ... Gang oft agley ...
Reply:Yeah Moonrise the ribs are steel and heat up faster than the cover.  Then they want to warp and not fit.The rod says to preheat to 600*f,  Another package says to preheat to 800*f.  I know from experience the hotter I can get the cast the better the rod flows.  The larger cover is tough to get up to 400.  On the last one I stopped welding to  RE PRE HEAT   As I was doing this, I heard a crack.  It was one of my tacks, so not a big deal, but still an oh sh*t what was that?David R
Reply:Yeah, preheat (re-pre-heat  ) on larger parts can sometimes be difficult.But cast iron really needs some heat (LOTS of heat) in order to weld it.  Without that dreaded PING happening.Yeah, I usually say 800F is a 'good' temperature to heat cast iron to.  And yup, sometimes you have to heat it for a while, take it out of the heater, make a quick weld, and put it back in the heater, and repeat.  And the radiant heat coming off of a piece of 800F+ cast iron is a might bit toasty!It's one of those 'simple' looking tasks/jobs that takes a whole bunch of planning and prep in order to do (right).  The best laid schemes ... Gang oft agley ...
Reply:Yo David, looks like a small battle on your hands.CAC just kinda says "WHAZZAT" with cast iron. Plasma works but it's slow also.With sections that thick you can get away with a lot and all you'll have is some underbead cracking. You can get Ni-Rod with less than 30% nickel in it for less money and it welds very similar to 7018 (looks similar too).Your pre-heats are fine I think, and even going to 1600 thermal treatment after welding won't fix the problem of underbead cracking later when the part cycles between different temperatures. You get some edge and underbead cracks early, then the part gets to a point where it's happy.Is this just a modification? Maybe a design boo-boo? They look pretty good as delivered...Matt
Reply:Sanford - I wonder if brazing would be workable with the  finished parts' application?If so, that would sure beat being on the edge of your seat, waiting for the "pop."Heat what you can in the oven, then have Lamont run a rosebud pre-heat torch while you braze ‘em up with a second torch.Otherwise, I'd suggest to skip around with short welds which are followed by intense peening with an air chisel.Good LuckLast edited by denrep; 01-25-2011 at 01:20 PM.
Reply:Oh, and don't forget some Champipple.  'Esther, it's the big one!'        The best laid schemes ... Gang oft agley ...
Reply:Yeah  "The big one 'lizabeth" is exactly what I'd be worried about with crack-prone cast. Last edited by denrep; 01-25-2011 at 01:37 PM.
Reply:too much champipple, yup denrep, it's Elizabeth regarding "the big one".Esther was the sister-in-law.    The best laid schemes ... Gang oft agley ...
Reply:and i guess Grady  is runnin the camera?idealarc 250/250 ac-dc tigidealarc 250/250 ac-dc tig #2 used for sticklincoln sp100hh125dual arbor grinder polisher30 yrs of hand tools52 pitch blocks 6p-26prake gauge -pitch gaugeG&D prop repair 918-207-6938Hulbert,okla 74441
Reply:David--are the castings going to be re-surfaced after all of this?Blackbird
Reply:Lamont is at school.   Grady only comes by at coffee time ..  IF I BUY.These are dividers I am taking away and adding.  It was a 4 pass heat exchanger.  I am making it a 6 pass, so strength is not a big deal.  Its only flowing water or oil.  I am going to try my fire blanket under the piece to help hold some heat in. Didn't I tell you?   NO WARPING according to my customer.  I told him I would do the best I can.  So far so good.Even at 60 amps the rod is a red noodle when I get down to the stub.  More heat and I could use less amps.  Pkg said 50 to 70 amps.  I am at 60.  David Edit :  Dave P, If I could get the dividers in EXACTLY correct, no.   So yes they will be resurfaced.  I was supposed to have 4 tops and 4 bottoms done today.  I have 2 of the smaller ones and 3.5 of the bigger ones done.   Going home for the day.Last edited by Fred Sanford; 01-25-2011 at 03:47 PM.
Reply:Fire up your old webber grill good and hot and set the piece in there to heat it up and just weld it right in the grill so it stays hot. Set it right in the coals if you have too!
Reply:Looking much better.  I preheated them even more and used some insulation on the bottom  I could get them up to 600 * f  give or take with an infrared thermometer.  They welded much better.  I also turned the amps up 80 for 3/32 and 105 for 1/8" Allstate 8-60.   The rod was a red noodle by 2/3 gone either size.   I would stop at half and use another rod.  When the first one was cool, I used the second half.Here is the amps for the rod from their web sitehttp://www.esabna.com/EUWeb/AS_handbook/596as2_17.htmAnd herehttp://www.esabna.com/EUWeb/AS_handbook/596as2_16.htmToday the customer told me if the ribs are off they will just straighten them with a hammer.  I think they do.  He also told me he has 10 more pieces.  DavidI don't know how I did that but see the gloves for insulation? Attached ImagesLast edited by Fred Sanford; 01-27-2011 at 08:26 PM.
Reply:Lookin' good!You could connect two stingers and then alternate between them for electrode cool-down time.Alfred says he would still like to see some peening of the warm beads.Oh and tell Lamont the draft's over, he can quit that school hustle anytime and get back to the yard to help out Pops. Good Luck
Reply:I recognize those end plates.  Those are for aftercoolers for an EMD diesel engine.  They probably say Young Touchstone on them somewhere?
Reply:Ahhhhh!Isn't there a big EMD upgrade and retrofit campaign on?Pretty good for a 75+ year old design.
Reply:Originally Posted by denrepLookin' good!Alfred says he would still like to see some peening of the warm beads.Good Luck
Reply:David/Fred,Yeah, cast iron likes it HOT.  Maybe check the side yard of the 'empire' and scrounge up some firebricks.  Use them to make an enclosure around the cast iron part, and put in a gas-fired forge/kiln burner pipe (more 'repurposed' items from the 'empire').  That should let you easily get those parts up to temp.Easier and should be a more even heat than standing there and waving a rosebud or weedburner over the parts.  Also a better and (usually) more efficient heat then an uninsulated gas or charcoal grill.Just an FYI.    The best laid schemes ... Gang oft agley ...I knew an OLD OLD timer that would weld on a bed of red hot coals to keep the big stuff hot while welding..dont tell osha , but he said it worked real good..
Reply:My dad had a forge and a lot of places I worked at had a wood burner.  I could put stuff in there.  I did get some insulation from my neighbor that has a heat treating business.  He offered me to borrow some of this insulation.  It worked great. This one I did NOT have to cut out the center.  It was different thoughThe parts didn't fit.Who was the religious woman that had the hots for Fred?In the spirit of an old junk man, I am using a propane weed burner to heat these up.  Too cheap to use acetylene.  The guy next door offered for me to use one of his ovens.  DavidLast edited by Fred Sanford; 01-28-2011 at 06:11 PM.
Reply:Aunt Esther his  sis in lawidealarc 250/250 ac-dc tigidealarc 250/250 ac-dc tig #2 used for sticklincoln sp100hh125dual arbor grinder polisher30 yrs of hand tools52 pitch blocks 6p-26prake gauge -pitch gaugeG&D prop repair 918-207-6938Hulbert,okla 74441
Reply:Hmm, now I see the second row of bolts, that is different.  I may post a picture of an EMD aftercooler and the similarities are striking.
Reply:Originally Posted by Fred SanfordMy dad had a forge and a lot of places I worked at had a wood burner.  I could put stuff in there.  I did get some insulation from my neighbor that has a heat treating business.  He offered me to borrow some of this insulation.  It worked great. In the spirit of an old junk man, I am using a propane weed burner to heat these up.  Too cheap to use acetylene.  The guy next door offered for me to use one of his ovens.  David
Reply:Originally Posted by Matt_Maguire  Snip...Didn't Aunt Ester have a barracuda friend from the church?Matt
Reply:she had 4 sisters Flossie,Minnie,Elthel, and Hazelso the  trivia  readsidealarc 250/250 ac-dc tigidealarc 250/250 ac-dc tig #2 used for sticklincoln sp100hh125dual arbor grinder polisher30 yrs of hand tools52 pitch blocks 6p-26prake gauge -pitch gaugeG&D prop repair 918-207-6938Hulbert,okla 74441