Welding Cast Iron...

[BCB]

For all you welders by trade, is it difficult to weld cast iron? Thanks...BCB

[MT Gianni]

some say it's impossible, others say it can be done but must be in a heat controlled environment ie take the item to be welded to 250*F weld then cool down in steps and you might do it. The problem with cast is there are so many different materiels than say a low carbon steel and they all expand at different rates so you are repairing a crack and causing another at the same time. My dad, a great do-it youselfer, says he welded 150' of cast sewer pipe before someone told him it was impossible and has never been able to do it since. I've never tried since being told it was almost impossible. Gianni.

[Phil]

I've seen it preheated and brazed but can't recall ever seeing it welded. Not saying it can't be done, especially with all the new welding equipment and techniques available today, just that I can't remember seeing it done.

Cheers,

Phil

[JSH]

Cast can be arc welded as long as it is not rusted and pitted really bad. The main thing I found was to treat it like you were brazing get everything very clean and don't over heat it.
A salesman came through when I was still working at the local COOP and had some rod that he said could weld about anything. It was not cheap and I had welded pillow block bearings that were cracked to just get by. Same rod I had used on SS with good sucess too. It was not cheap. I think the name brand was X-ergon or some such spelling.
Be warned if you try to braze it that brass will flow into the bores of the cast iron and you never will get it to weld.
If this an exhaust manifold I will say you are SOL to be honest. I have seen welders that new what they were doing weld and braze them up. The biggest bunch of them will crack sooner or later.
Are you sure it is cast iron and not cast steel? I have welded truck hubs up that have spin the duals and would not tighten down with good success.
Also don't laugh but I have used JB weld and some of the other type stuff with fair success in years past, mostly on very clean surfaces. Used some high temp stuff on an exhaust manifold a long time ago and it is still holding.
Jeff

[walltube]

For all you welders by trade, is it difficult to weld cast iron? Thanks...BCB

specific about the object, ie; engine block, ex. manifold, transmission case, etc.

Generally speaking, the higher the quality of the material the less problems with welding.

W'tube

[BCB]

JSH,
It is the grate in a wood/coal burner. I think it is cast iron, but you might be correct about the cast steel. I don't know that much about it. I do have an uncle who is a certified welder, but I thought I might just ask here. I have heard him mention the "magic" rod you are probably discussing. Maybe it is some type of nickel. Oh well, I will just continue to read the replies, but I think you are correct about it being quite difficult to weld...BCB

[castalott]

howdy...
Back when I was a pup, my dad welded a cracked 4 bolt chevy block for me. The crack was in the oil gally area and was quite large. He drilled holes past the crack and then tapped the crack with a hammer until the crack extended into the holes. This stopped further cracking as the drilled holes became a radiased end for the crack. If you don't do this, the crack will just continue as you weld it. He then V'ed the crack out with a grinder and welded with ***** "I THINK"**** ...a stainless rod. You can only weld a second or 2..then you must let the entire weld cool to touch.If you weld very long at all, the heat will break the cast. It took the better part of an afternoon to weld a 3 inch crack. His 2 best buddies were special welders at a local power station. They told him how to do it. That motor ran 6 years in a hot rod Z-28....no problems...

[357maximum]

I have seen it done a few times on "temporary" gas main fixes....very complicated and a surgically clean operation....high nickel rod,,,I believe it was called Certanium or something like that....there was only one welder among 12 to 15 or so that was ever called upon to do it....preheat/post heat...is the critical part of the equation...I saw it done but I would not attempt it....my welding skills are decent,,,but that cast iron welding...that appeared as an art form...mystical voodoo stuff...


Good luck..

Michael

[kywoodwrkr]

Keep in mind Lincoln wants to sell welders not services.
Read some other rather gloomy articles about welding cast.
Then discovered they were selling a welding service.
Well, oh duuuh.
I'd say it was impossible also if it meant I got the welding job instead.
Anyhooo, here is link to Lincoln's take on it.
http://www.lincolnelectric.com/knowledge/articles/content/castironpreheat.asp
I've sometimes gotten information at this website about this topic as well.
http://www.ford-trucks.com/
FWIW
DaveP kywoodwrkr

[ron brooks]

If it is a wood stove grate, I think you are out of luck. The problem is, as has been said earlier that the cast is going to heat at different spots at different rates. Now that the "unity" of the piece has been destroyed, even if you get it to weld, it will crack again next time it's used and heated up.

I would suggest welding up a brand new grate and put your effort there rather than on repairing the old one just to have it break again.

Luck,

Ron

[kenjuudo]

Welded up many a cast iron press frame with Hobart Nicklecast 99, remove as much surface rust in the area as you can, Vee the crack well, preheat and weld it with AC, use a stringer bead, peen the weld with your chipping hammer, peen the hell out of it while still hot, relieves most of the stress.

jim

[RayinNH]

BCB, if it's a grate for a wood or coal stove it's cast iron for sure. Cast iron is used because of it's ability to withstand very high temperature without burning away. As walltube said the better the quality of the cast iron the easier it is to weld. Machinery parts and that sort of thing that are subjected to some stress are good quality cast iron. Grates for stoves or fireplaces do not fall into that category. Two types of welding rods are used, machinable and non-machinable. Machinable consists of nickel. That would be used if the part needs to be filed, drilled, tapped or some other machining process. Non-machinable( not sure of the makeup as I've never used it) would be for just putting two pieces together such as your grate, the welds being very hard, can only be ground.

I weld cast iron about 2-3 times a week. I weld decorative spear points on items that I make. These are the type that you see on railing, gates and that sort of thing. I TIG weld these using stainless steel wire, for it's nickel content.

I have tried welding fireplace andiron dogs ( the part in the fire)
with nickel rods before, several times in fact. I have never been able to do it yet. It's like welding with a cutting torch. The metal keep blowing away from the weld faster than you can keep up. I can't prove it but I suspect it's because the metal soaks up carbon from the fire. As any weldor knows, the higher the carbon content the more difficult it is to weld.

If the weldor is willing to do the job and only charge you if succesful then go for it. You may be better off with another type repair, bolting or pinning for example...Ray

[grumpy one]

I have only tried to weld cast iron three times, but I had the advantage of knowing it could be done. When I was a teenager I milled the intake ports of a side-valve engine through into the water jacket. Getting another block would have been difficult, so it was sent to a welding shop and repaired successfully - ports were ground and polished and engine was put back in the car and used for years. My own first effort was aimed at gas brazing a cast iron tractor seat, and I failed, but I know it can be done so it was probably poor preparation and/or the wrong flux.

My second attempt was on a set of lower links from the three point linkage of my tractor. It was an industrial tractor and the links were massive. When I bought them they were badly bent, and when I straightened them under the press they cracked slightly across some holes that were part of their design. Being under the impression that they were forged steel, I used mild steel rods, and found that a crack always formed at the edge of the weld bead due to differential shrinkage on solidification. I was later told that they were cast "semi steel", and they'd have been easy to weld if I'd used cast iron rods.

My third attempt was when I'd cracked the cast iron base of my Taiwanese bench drill by clamping it too hard - the bench attachment bolts were located in a place where there was no support underneath, making a bridge situation, so over-tightening cracked the vertical webs of the drill base. All I did was get a few commercial weld rods made for cast iron welding, warm up the rods (not the job) by running a bead on a piece of scrap, then just welded the drill base as if it were a piece of mild steel. I deliberately built it up on both sides and made the drill base around three times as thick as the original design in the area where it had cracked, so it wouldn't happen again. The casting was only about an eighth of an inch thick I guess.

For what it's worth, my old welding instructor said you must never grind cast iron before you try to weld or braze it, because you'll smear the embedded graphite and make the job impossible. Use a sharp file, or mill it, or don't V it at all, but don't grind it. With the drill base I didn't V it or prepare it at all, because it was thin and I knew I'd get full thickness penetration with a fairly moderate current (which was specified on the packet the weld rods came in). I didn't pre-heat, but I did start at the inner end of the crack and let the area heat up by conduction while I was welding slowly. By the time I had a warm rod and a warm job, it was just like welding mild steel. I ended up feeling like a hero welder, without having actually done anything difficult.


Geoff

I

[walltube]

now that we have the critter at hand ,BCB, and much has been presented here, it may be in your best interests to find a replacement for the grate. Grates were made to be replaced, an expendable item.

I say this because the cost and effort to repair a "low grade" cast iron piece is Dollar foolish unless it is something of an historical value. The term 'low grade' I use means that the casting most likely is porous with high amounts of sand (silica) from the sand mould into which the melt was poured. Little care was taken at many foundries to keep other impurities from being introduced into the molten iron. Carbon inclusion in particular: see RayinNH post. A sound weld is at best difficult if not immpossible with such materiel. There are other factors involved with such castings but I'm keeping it brief here.

I wish you the best of success with whatever options you may choose. Good luck and keep us posted.

FWIW & Yours Truly,

Walltube

[Four Fingers of Death]

A blacksmith might be able to heat up and cut the section out and then hammer weld a new piece in. He could 'weld' the crack up by heating around it to red hot/plastic state. and then treating it with borax (I think) and then hammering the bee whatevers out of it until it flows together. Probably not worth it. Don't laugh, but have you tried muffler putty? I fixed a rusted cast BBQ burner using this, ran ir for an hour or so to burn off the yukky chemicals, worked for a year or so and I gave it to my son. who also used it for a year or so and then left it at the flea trap he was renting in Sydney (another good BBQ followed this one down and met with the same fate, he's on his own as far as BBQs go now.)

[Four Fingers of Death]

I forgot, take it along to the welding class at the local technical college, they love this sort of stuff.

[Jon K]

Eactly what Ray and Walltube said. Buy a new grate because the junk and carbon in the grate. Besides that the Ni-Rod will cost you as much or more than the grate.

If you just want to try your hand at welding cast iron, do like Mick said, take a welding class.

Jon:castmine:

[carpetman]

Obtain an old blender that the higher speeds dont work but slow speed does. Problem solved. Slow speed on a blender is grate.

[RayinNH]

Mick, he'd be better off with a magician. In my 28 years of metalwork I've done my fair share of forge welding as well, cast iron can not be hammer welded. That too much carbon thing again...Ray

[BCB]

Thanks for the info…I sort of figured it would not be an easy task repairing the grate. I sure got a lesson on cast iron--complicated stuff it seems!!! It is in a Sears/Craftsman woodburner that is over 25 years of age. So if the grate was still available, it would probably cost more than the woodburner is worth!!! The grate is only broken where the shaker handle hooks into it so the ashes can be shaken down to the ash pan. Not really a problem as the ashes can be poked down to the pan with a small shovel or the likes. I actually purchased a new Hitzer woodburner and it is working well. I was going to put the ol’ Sears in a garage I use only occasionally. Ain’t no big deal. There sure is a wealth of information about any subject on this website. Not anything that can’t be explained or advise given…thanks again…BCB

[ebner glocken]

I am a certified welder by trade. The problem with cast iron/steel is that it does not expand nearly as much as the filler you use. That's why they use it in such things as stoves and engine blocks. The filler goes in hot (expanded) and then cools thus pulling away from the parent material thus leaving cracks along the weld line on each side of the weld.....usually. This leaves it looking like it hasn't "tied in" someone not familiar with cast will think they need to go higher in amps (this makes the problem worse). If your amperage is too low it will usually crack out in the centerline of the weld or if you didn't bevel it deep enough/wide enough.

In order to make this even out you have to preheat the parent material to around 250*F to 275*F in the heat affected zone so they cool more evenly with the weld seam and filler material. Lets say you have a 1/4" weld line, you are going to have to preheat around 2" each side of the weld line to get the expansion/contraction zone to get the weld to follow and not "go on it's own" and pull away.

You can stick rod this weld with speciality rods sold for cast welding or you can use 309L stainless rod. I have found that 316L works and is more forgiving. Use both of these rods with a positive electrode for best results.

You can TIG these (this is by far the easiest). In my experience 316L or 317L (I usually use 1/16" rod for the root) works best.

Be VERY sure to clean out the seam like it was going to X-Ray. Bevel it at least 30 degrees but no need to go more than 40 for best results. Make sure you clean the heat affected zone with your grinder of debris, mill scale, etc. I like to final clean it out after it has cooled down from grinding with acetone, mineral spirits....pretty much any cleaner like that as long as it doesn't leave any residue.

[ebner glocken]

Oh forgot one important thing... Let it cool back down to around 250* bewteen weld passes or it will crack out on ya. I'm usually staring right at it with a hood up and hear that "CHING!!" This usually makes the welder say very sinful things, question his abilitys, and if his parents marrage was legal.

[walltube]

Oh forgot one important thing... Let it cool back down to around 250* bewteen weld passes or it will crack out on ya. I'm usually staring right at it with a hood up and hear that "CHING!!" This usually makes the welder say very sinful things, question his abilitys, and if his parents marrage was legal.

Hoo boy, them Golden Arm weldors are a picky enough bunch aren't they? :)

Just teasing here, Buddy.

It's bad enough having to repair your own weld much less another's mess, ain't it? Make a good man cuss in languages not yet invented, sho-enough.

Walltube

[ebner glocken]

LOL... I got out of the trade 3 years ago and don't miss it for a second. Yes, it is amazing that a huge part of the people I worked with at 3 different companies were legends in their own minds. Come to think of it I know of a couple in the company I work at now that are. Make that 4 companies. But than again I've seen this applied to other trades as well.

[MT Gianni]

Thanks for the info…I sort of figured it would not be an easy task repairing the grate. I sure got a lesson on cast iron--complicated stuff it seems!!! It is in a Sears/Craftsman woodburner that is over 25 years of age. So if the grate was still available, it would probably cost more than the woodburner is worth!!! The grate is only broken where the shaker handle hooks into it so the ashes can be shaken down to the ash pan. Not really a problem as the ashes can be poked down to the pan with a small shovel or the likes. I actually purchased a new Hitzer woodburner and it is working well. I was going to put the ol’ Sears in a garage I use only occasionally. Ain’t no big deal. There sure is a wealth of information about any subject on this website. Not anything that can’t be explained or advise given…thanks again…BCB

Sears does keep parts for stuff far longer than anyone else in the industry. You might check with them. have a mod and ser# handy. Gianni.