Welded cast iron gone hard-Any way to soften it?

Customer has a 2'x3'x2' complex casting that had 2x 3/4-10 holes, 3" deep full of oil and dirt that were stripped and had broken bolts. One bolt had a broken easy out 2" down.

Welder decided to just pour the wire feed to it and fill it up in one shot, bolt, easy out and all.

Course its harder n' the back of gods head now, with no space to move the bolt holes, no space for a through bolt either.

Its one of those projects that will come out on a Saturday, has to go back in Sunday afternoon for Monday shift.

The bit of reading I've done says that once it goes hard, anything other than a slow controlled cooldown won't help reduce the hardness by much.

I don't have access to an oven big or hot enough to throw the whole thing in.

Any practical way to get it soft enough to drill and tap?

Thanks!

Use some sort of holesaw cutter to remove a 2" or so slug. Just big enough to get outside the hard zone. Thread that in then drill and tap your holes like normal in that slug.
If you try local heating you risk shrinkage cracks in the casting. Drilling the hardened cast iron mixed with the EZout does not sound like fun

First step is to have that welder slowly set the mig gun down and back away slowly

Strostkovy said:

First step is to have that welder slowly set the mig gun down and back away slowly

Click to expand...

Sounds like it's too late for that. A good heavy smack upside the head sounds like a better solution (for the weldor, at least).
As far as the part goes I suspect that Rob's idea is as good as it's going to get. You can get away with a long annular cutter or
holesaw if the hole isn't blind and you can cut all the way through. If it's a blind hole you have a problem--no way to break out the
slug. You might be able to plunge in with a carbide endmill but I wouldn't hold my breath.

The bottom line is that you need to get a hole in there in which to thread a solid plug. Once you get there you're golden. If you
don't have a long annular cutter you might be able to trepan the hole in but the same deal applies, you gotta get rid of the slug.
An EDM machine or a tap disintegrater might work but that would likely be a slow and costly process

A full oven soak and slow cooling might anneal the hardness but even that is doubtful. It isn't just the heat that caused the hardness
but also the combination of the dissimilar metals and all the heat treating in the world isn't going to change that. The inclusion of the
easy-out in the mix is a particularly nice touch.

I feel your pain as I have been in similar situations in the past. For us the one consolation was that any rogue welding was the
doings of the customer and not us--we had nothing to apologize for. The thing with cast iron repair is that sometimes the hardest
way is actually the easiest. You've got to know when to punt and too many times people will try to make one more play before they
do and by that time it's too late. Boring the hole out before any welding was done and planning to put in an insert would seem at
the time to be a lot of work but clearly it would have been the simplest solution.

Show us a pic or two; we might see something that could help and do let us know if you come up with another solution...

ManualEd said:

I don't have access to an oven big or hot enough to throw the whole thing in.


Thanks!

Click to expand...

Take it out in the yard and build a big ass fire over it, and keep a stoking

All that MIG wire might have softned the Eazy-Out a bit as the cooling that deep in the mess will have been a bit slower. especially if its one of those cheap, snap as soon as you lean on it variety.

Hope you have access to a mill big enough to hold it or at least a drill with reliable means of getting things central

I've had some luck in similar situations with high end centre cutting carbide endmills. Five flute ones in particular. The ones I found proved well up to cutting through snapped off taps. Don't recall the exact brand but pretty sure it began with N.

Other things that have worked are die grinder points. Both ordinary abrasive and diamond. Very slow. Hole is less than round so you will need to cicularise it with a carbide end mill before re-tapping or whatever.

Wonder if the high pressure, very low speed with a new, unused, masonry drill trick actually works. Allegedly folk have demonstrated drilling through bearing races and the like with Cole or similar clamp on drills. If it does that might be up to going through the hard bits. Or maybe those wonder drills that used to get demonstrated turning files into swiss cheese at, seemingly, every other exhibition I went to.

Clive

Clive

Make it clear to your customer that you are doing the work on a best efforts basis. Just like a doctor, you get paid even if the patient dies. Also make sure they know their welder did them no favors.

I'd try drilling on the proper location and see what happens. I'm sure you can put a hole in it. Second prize is putting in a sleeve and tapping the sleeve at the right location.

Sami’s suggestion is really not a bad idea. Next to the fire set a large container of fine sand, enough to cover by several inches all around and pack it in real well. Coarse sand allows too much air flow, and don’t forget to pour sand in any cavities first before burying, and come back in a couple days.

upthebikes said:

Sami’s suggestion is really not a bad idea. Next to the fire set a large container of fine sand, enough to cover by several inches all around and pack it in real well. Coarse sand allows too much air flow, and don’t forget to pour sand in any cavities first before burying, and come back in a couple days.

Click to expand...

I would pick vermiculite or perlite over sand.

A thought - if you can get lots of charcoal - it's much better than wood

Unless the welder used massive pre and post heat, odds are that you will find extensive cracking in the casting.
Mike

If you supply a keg of beer I would bet you could get college students to keep a pallet fire going over it until the keg ran dry. Probably a good idea to keep pallets coming to them also.

upthebikes said:

Sami’s suggestion is really not a bad idea. Next to the fire set a large container of fine sand, enough to cover by several inches all around and pack it in real well. Coarse sand allows too much air flow, and don’t forget to pour sand in any cavities first before burying, and come back in a couple days.

Click to expand...

I don't think he has time for all of that, remember, in on Saturday and out on Sunday.

JH

I doubt that the MIG weld is very well bonded way down deep. The top layer is probably the worst. Still an awful bitch to work on. i'd guess that maybe you'd have to go as big as maybe a 1.25" threaded insert to get to a tappable material. Just have to worry your way through it with tap extraction techniques for hard drilling.

Can you set the thing up in a mill to interpolate the holes? That way you can sacrifice many smaller endmills as you try to helix your way down with a very shallow helix. Potentially thread mill the new threads with a single point carbide that you can change a few times if it doesn't make it through the cut on the first try.

James H Clark said:

I don't think he has time for all of that, remember, in on Saturday and out on Sunday.

JH

Click to expand...

Sometimes you have to have time, …………..and the customer f'kd the part up -NOT the OP

Sometimes you have to say no.

If you can preheat the part all over, use a very small airarc carbon and eat a hole down the middle most of the time the weld wire will not adhere very well to the casting you can chip out the pieces then let cool very slowly. You can then install a plug and drill and tap to correct location. I have had to do this a few times on large gear boxes, especially when they drill at a angle through the bolt and in to the casting then break off the easyout and it's now locked together..
Good luck just go slow and remember to try to keep heat stable.

A pic would be great... I would probably plunge in there with a carbide end mill.

To soften cast iron just heat it up till its red and drop in a steel bucket full of lime, cover the part with a good 5 inches of lime. let it cool over a day or so.

You can try drilling with a resharpened masonry drill in the hole location and see how you go but couldn't say it would be plain sailing esp since its a mix of metals. The masonry drill can be sharpened like a normal drill on a green wheel in a pedestal grinder. They are cheap and generally work well.
I would be having a word with the welder about his hack job too.

Curious what mig wire the welder used