Disk Weld Cracking?

[stryfe]

Hello all, I'm a little new to the group and new to Disco's

I made my own a few weeks ago, from a disk I got from a farmer in AZ. I welded a piece to fill in the hole in the center but have noticed my welds are cracking. Now, I'm not a professional welder, a hobby welder only.

I tried last weekend doing a little grinding and rewelding the crack but have seemed to only make things worse, the welds cracked even more. I'm guessing it has to do with the difference between the very hard Disk and milder filler material and the amount of heat and cooling rate. So..

1) what do most use to fill the disk holes? I wish I could have used a scrap piece of another disk.
2) Any advice on how best to go about fixing my cracking issue?

Thank you
Craig

[Bricklayer2]

I replaced the disc on my harrow a few years back. The disc that was available to me had several different grades or quality depending on how much you can or want to put into them cost wise. The better quality was a tempered steel so I am wondering if you would heat the whole disc to anneal the steel if it would allow for a better weld. I am thinking if you have tempered disc you are getting a localized anneal in the steel creating stress cracks. Just my opinion though. ;)

[ajfoxy]

Yes, I'd be of the same opinion as Bricklayer2. I think if you could heat the whole thing to slightly under cherry and then put it in Perlite/kitty litter/sand to cool slowly you might be able to weld it a tad better.

[stryfe]

Unfortunately, I have been thinking the same thing. Ok now to figure out how to anneal a 22" disk, LOL

[ajfoxy]

A couple of weed burners, a few dozen beers and you are done. Do not pour the beer on the hot steel it will harden it...
Don't forget to cool it slowly. A couple of bags of kitty litter/perlite or similar and bury the almost cherry red disk. Consume more beers and the next day you can grind out the old weld and reweld it.

[stryfe]

I've got a 65,000 BTU burner, do you think that will get it hot enough?

[ajfoxy]

Possibly, but two or more are preferable so you don't have to chase the heat around. Get a buddy to do one side while you do other. That still leaves the left hand free to hold a sample of your favourite beverage.
If you are stuck on how to heat up the disk on your own... find a drum that is not useable for a UDS cut the bottom third out (leave the bottom on). Poke a few holes around the edge for air. Fill up with wood, charcoal, brickets etc get roaring flame and lots of heat. Put your disk on top (not in) and heat it up. Then attack the top with your burner to speed up the process. Have your kitty litter in the top bit of the drum ready so when it gets just off cherry, you don't want to overheat it, you can put it in the kitty litter, pour more kitty litter on top and leave it until the next day.

Just an aside: Metal at just of cherry or less (dark heat) burns you way worse than white hot metal. White hot metal will sear and drop away, black hot will stick and create a very painful burn. DO NOT touch it to see how hot it is...

[stryfe]

Don't touch Hot Metal!! Check.

I'll pick up a weed burner and see what I can do this long weekend, Thanks for the advice.

[The Czar]

Well do you still have fingerprints?


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[Frank_Cox]

plenty of beer.... got it

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[Dirtytires]

I think I got the same disk....bought mine new tho. I have the same problem but it's holding so I'm probably gonna just live with it unless it gets worse. Sounds like you are in Az...I'd be interested if your farmer has a pile of disks and just wants to get rid of them. I like your idea of cutting a patch out of a scrap disk but I'm not buying a new $40 disk just to cut a 2 inch square out of it.

[nanuk]

wouldn't laying it on a wet rag, and slowly stitching it work OK?

[Dirtytires]

My understanding is that it cracks because the two metals cool at different rates which pulls it apart by cracking...but I’m not the expert.

[74quadravan]

Are you referring to the center hub hole being welded up?
I did 2 discs with a 120 volt wire feed welder and one of them cracked 3 times. We had good clean steel and proper bevels. The patch for within a 32nd all the way around. Last time we used a propane weedburner to preheat the metal before welding and then again to even the heat after the welding. Let it cool gradually. No problems that time.