Brazing cast iron

I'd say get it welded, if you can find some one who can do a good job on it.
Not my field of expertise...just a cat gut feeling.

Del

Kobus Lee

There are special rods made for arc welding cast iron. I recall us using one several years ago. We got it from Bowman Industries - Barnes group. We built up the damaged area - ground it down - and repeated the process until the hole was filled in. Contact a local welding supplier. They should have the same or equal product available. It would be a mistake to put a torch to it in a brazing attempt. Ed

I would be sure to find a person that specializes in cast iron welding....... not just someone that can weld.

This is cast iron. As an old gearhead, I'm not going to say it can't be done, but -- and please pardon the expression -- it's a cast-iron bitch to weld it right. You may want to seriously look into just getting another head and save yourself a lot of grief.

I have seen many attempts to braze cast iron. I haven't yet seen a successful one. Under load it cracks, usually one side or the other of the braze.

In this case you have large temperature variations stressing your repair, and there is quite a mismatch between the coefficient of expansion of virtually all brazing rods and cast iron.

There is a special high nickel rod made for welding cast iron, nothing else seems to work satisfactorily.

Degreasing of the area is important. Because of the porosity of most cast irons, water, oil, inhibitors etc absorb into the metal and destroy the integrity of your weld. It does even worse damage to brazing.

Get a specialist welder who knows how to do this work and get it welded. The job is unlikely to be cheap, but short cuts will probably be disastrous.

Good luck

I have worked with cast iron equipment on many occasions that had been successfully brazed. It is the expected load and the tin content which determines effectiveness.

I believe you can use 309 ss rods to weld cast iron, but make sure the welder has experence with this.

Jim C

the best welding rod to be used should be coated pure nickel rod or SS312 coated rods. The only difference you will get in these is the hardness of the deposit. While the Nickel rod is soft, the 312 SS would be hard to finish. Another alternative is to fill the hole with a NiCrBoSi powder of low hardness using a spray and fuse torch. This materrial has a very low, 1950 degrees F melting point. It is always good to preheat the whole head to about 800 degrees F before starting to either weld of spray fuse it for repairs. Also after completely welding it cover it up in something like vermiculite so it cools slowly. I have handled a lot of this stuff during my professional career.

Good luck

vshwn7@aol.com

We have been successful in welding cast iron, and I would recomend it over brazing.There is a process that has to be followed. There is a preheat and a post heat. You can do a search on welding cast iron and alot of good information can be found. I would also recomend that you find a qualified welder with experience in the field. Do not attempt without knowledge of the process.

"There is a preheat and a post heat".

Only answer I read that dealt with THIS ISSUE .

VERY IMPORTANT

We do CI often.......slow/even pre heat and slower post heat is always critical to the structural integrity of CI welding.

Post heat = immediately wrap in FIRE SAFE insulation ....odd shape?..bury it in DRY SAND...............( AT LEAST THREE INCHES/all sides ), let cool to ambient temp. for four hours........longer if your ambient is cold to humans.

Last one we did weighed about 80 pounds...4 " X 1" ...WELD....took ALL DAY..........

MR. GUY

The head will have to be cleaned. Once you have removed all the grease and other contaminates a bake out process around 375 to 425 degrees F should be performed to insure that the casting is stress free and the pores clean prior to the weld. Now some castings are made of very low grade casting alloys and for the most part they are un-weldable. The trick to welding cast is maintaining a preheat and inter-pass temperature. I would suspect that you do not have any no-contact temperature measurement equipment at your disposal so just follow these basic rules and you should meet with success. Grind out the crack completely, don't leave any remains of the crack because it will reform at a latter date causing the same problem as before. Preheat the entire head so that it is a dull red color. Using a pure nickel rod "TIG" in the crack. It will require some protection as far as heat radiating from the head. I have often built a mock furnace using ceramic blocks and torches. The temperature and color of the head needs to remain constant. Once the weld has been completed you will need to slow cool the head. If you cool it to fast it will warp and crack adjacent to the weld repair. Allow a minimum of 24 hours bringing the temperature down uniformly until the head is bellow 200 degrees F. You may need to re machine the head surface to bring the tolerances back. I know of after market shim gaskets that will make up the slight depth differences caused by the machining. If you are really good, you might be able to blend the area of repair and not re-machine the head. Remember not to bring the hight of the repair bellow the deck hight of the head.

One more precaution while working with cracks. It is best if you can drill small maybe 1/8 inch hole at each end of the crack and then procede to weld it, this will help in avoiding the crack to develop again at the same place.

vshwn7@aol.com

Yaddy yaddy...Get another head and move on. Cast iron is made with sand. Can you weld sand ? It will be a pain in the behind forever. get another head.

At engine building shops, you see hoppers full of bad heads. They're not worth the bother.

Get a good working head from a junk yard, or have someone locate one here the the US and ship it to you.

Don't waste your time trying to fix it. you'll spend more time than it's worth.

Sometimes a scrap is just that. It happens...

Toolmaker

This seems to be a new discovery worth a Nohel prize, "Cast Iron is made of Sand" Ha, Ha, Ha!!!!!!!

vshwn7@aol.com

prevention, prevention ,prevention.,...... use a pair of inside dividers to measure how much metal you are removing from each area of the port. most heads will tolerate .060 metal removal from most surfaces. more is asking for trouble. a sonic thickness tester would be good insurance to keep from hitting water. but if you have that available remember that the shape of the water jacket is usually not the most efficient. as for repairing, its likely that the area is thin for quite some area around the hole. you will need to cut the hole out so you have a wall to weld to that is at least 080 thick an preferably .125 and then cut a cast piece of iron, a broken cylinder wall sleeve is good, and grind - file - cut it to the shape of the hole. then as people have said before the head needs to be preheated, welded and slowly cooled. good luck