Cracking on 18K red gold wire while rolling.

Monkegard

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Hello all, I am brand new to this forum and figured I'd create an account to see if any of the questions I can't find answers to through online research might be solved here!

I recently found a thread created by purplepepper8 about cracking caused when rolling out a gold ingot. My problem seems fairly similar other than I am rolling wire rather than sheet. From the replies in their thread I can only assume I am quenching slightly early when annealing. But from what I've found online it sounds like quenching when still red hot shouldn't be a problem.

I am heating my ingot/wire to a cherry red and quenching in water, then putting in the pickle. After the first annealing I don't see any problems but once I anneal a second time I start seeing hairline cracks that only grow larger as I continue to roll the wire out. I tried quenching once the metal turned black from red and experienced similar cracking so I am wondering if I might be doing something else that might cause the cracks(I also find them when I'm rolling out silver wire). The casting grain is from Hoover & Strong and they recommend an annealing temp of 1400˚ F; I've tried annealing both with a torch and setting a kiln to 1400˚ F and leaving the metal in for 10 minutes.

I'm also wondering how many times metals can be melted down and reworked before I should send it back to the refinery and get new material.

I'll attach a few photos of the cracks I am getting seen through a loupe and straight from my phone.

Any advice is greatly appreciated!

Thanks,
Monkegard
 

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monk

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welcome to the madhouse. i'm sure there are several members that can and will answer this question.
 

LahtiM39

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Red gold work hardens rapidly. When you are melting for an ingot it is important to use a clean (dedicated) crucible to avoid contaminants. Sometimes air cooling will work for annealling.
 

DanM

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The main question is why you would use casting grain instead of just ordering wire? I was taught never to use casting grain for anything other than casting. No metal from any company is perfect at all times. Many years ago I worked 2 pieces of 18K red at today's price would be around $14,000,they both developed massive cracking with rolling and forming. Everyone has their own opinions,see link.

 

mdengraver

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This happened to me. I believe when using the rolling mill you need to keep flipping your ingot but always rolling it in the same direction. As the crystalline structure of the metal work hardens if you change directions the crystalline alignment gets thrown off causing cracking. Also every few passes thru the rolling mill it becomes necessary to reanneal the metal to prevent the metal from getting brittle causing cracks. When finished rolling thru the rolling mill don't forget you still need to anneal the metal once again to relax the metal from work hardening. Also try to roll the metal in the same center location of the rolling mill each time if possible to protect the rollers and to achieve a more equal pressure on the metal while rolling it.
 
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Brian Hochstrat

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I make my own red wire and sheet in various karats. The more copper in the alloy the more often you need to anneal to avoid cracking, which as stated is the result of work hardening. On sheet there is always some cracking at the edges but overall if you anneal every other roll when it is still pretty thick you can keep it to a minimum. Once you get it down smaller you can take a few more passes before annealing and be okay. Your 18k wire is less prone to cracking, than sheet would be, but I still anneal wire pretty often. With experience you will feel when it is starting to get too hard and you need to stop and anneal. As in I pushed it too far now it's all cracked up and I get to start over. Also I quench in alcohol. Okay, I hope that helps

As an aside, I also charge more for colored work than standard gold, because of the added time and expertise required to execute it.
 

Mike Cirelli

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Brian’s right rose gold will harden up a little faster than say yellow gold. I don’t go past the 50% volume when rolling or drawing before annealing. You definitely don’t want to use rose gold casting grain for rolling or drawing. Unless the company states it can be used for casting or rolling. Metallurgists specially formulate alloys for specific uses of the metal. Stray away from that and you run the risk of failure.
 

Chujybear

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Lots of trouble over the years specifically (only) with 18kt red gold.
Lots of little things I have heard, and I throughly everything at it and get decent results. Sometimes I get a fracture and make two pieces of plate or wire intead of one.
All said here already, but
Don’t keep the heat on it too long. Up to a dull red after pouring and quench when black.
Subsequent annealings don’t need dull red. Just get it up to annealing temperature and quench immediately.
Anneal frequently as you roll.
Always roll in one direction (this isn’t special, just sop

It’s quite nice to engrave if you wind up with a nice piece. But at worst it can be inconsistent with even crumbly sections.

My best reccomendation is to not use a red gold with a pure copper alloy. Adding a small amount so silver to your alloy will still give you a ,so called, bright orange alloy. And is very attractive and a lot easier to work.
I know that doesn’t help you when you’ve boaght pre alloyed grain.
Maybe add an ounce of fine gold with a sterling (or better, half silver) alloy mix to about two ounces of your casting grain. Should still be in that pink spectrum, I think.
 

Monkegard

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I thank you all for your responses and apologize for such a long period of time in my reply!

I contacted the refinery I purchase through and was able to speak with their metallurgist. He did not mention avoiding the use of casting grain to create sheet and wire, but he did suggest that I may not be cleaning the build up of oxides off of my ingot before rolling, as any imperfections on the metal will get forced into the metal as it is rolled and will cause the metal to separate after it is compressed.

I tried to clean the next ingot as best as I felt I could and the number of cracks dropped DRASTICALLY, although there were still some. I will try every suggestion I get and see if my results improve!

Thanks all for any help!

Monkegard
 

Eric Olson

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Cherry red is too hot for annealing. A dull red in a dark room should be enough. I also read to quench red gold in denatured alcohol for a slower cool-down. OK for small pieces but you don't want a large open container of alcohol around, obviously.
I set it on a steel plate and don't quench in water.
 

silvermon

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All very good advice above. As you can see you are balancing two big variables; annealing and rolling. There is a third smaller variable; the torch. You want a gas and tip combination that gives higher BTU with moderate or lower heat. Rosebud tips with natural gas or propane are good.
 
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in my experience quenching cherry red ingot right into water isn’t a good idea. I’ve had an ingot break into multiple pieces doing the same thing. I heat my ingots to a dull red and let them air cool for a while before quenching in hot water.
 

pblack

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Have you tried forging the ingot before putting it through the rolling mill? Forging will help compress the newly poured ingot using less pressure than the rolling mill. After processing the ingot some, you can then run it through the mill without stressing the metal as much as it would a fresh ingot.

John Sartin has a good video on processing a silver ingot. He also has how he poured it and one on pulling wire.

Ford Hallam has one on making Shibuichi (Japanese copper alloy: 1 part silver & 3 parts copper) where he forges the ingot to prevent cracking.
 

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