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Reelmaster
12-13-2003, 09:21 PM
Hi Guy's, I have some Rivetting Punches I have machined up from Drill Rod (Stubbs English Silver Steel) & would like to know the most sucessfull way of hardening same, I believe this steel is reccommended for Water Hardening.
All sugestions & recommendations will be greatly apreciatted. Many thanks. Best Regards. Jack Erskine. Precision Reel Engineering. Cairns. australia.
www.jackerskine.com.au (http://www.jackerskine.com.au)

BC21OSH
12-13-2003, 11:39 PM
Jack,

The process would consist of heating the piece to the critical temperature. This should be specified by the steel manufacturer. It is best to not apply the heat directly to the piece but heat a medium that will transfer the heat to your part, however many tools have been made by direct heating with a torch or in a forge so this is not a rule carved in stone. The best way to determine temperature if you don't have a furnace and are using a torch is with a temperature indicating crayon. Once the part reaches the desired temperature quickly pick it up by the non working end with a tong and plunge it straight down into water that is at room temperature. The container should be at least 15 - 20 inches deep and 15 - 24 inches in diameter. Once you plunge the part into the water begin to rotate it around the container, keep it moving until it is cool. You will then remove it, polish it some so that you can temper it. To do this, again heat it but just apply heat to the non working end and watch for the color change. The polished metal will begin to turn color and the color will flow to the working end. You want the working end to turn a light to dark straw color for a punch. Once the color reaches the end, you want to quench it quickly again. Very little heat is required to bring the part up to temperature for tempering so it can be done with a propane torch or similar such heat source. The idea is to heat it slowly and watch it very carefully being ready to quench it as soon as you observe the proper color.

Bernard

Joel
12-13-2003, 11:52 PM
It was recommended to me some time ago, to use a magnet to find the critical temperature. Heat with a torch until the steel is no longer magnetic, then quench. I usually do the temper in my kitchen oven. I have had good luck this way on W-1 and O-1. You need to determine how hard you want the steel to be. Machinery Handbook has some good information on all of this. If you don't have it, you can get the tempering temperature data from the MSC catalog, McMaster Carr's website (I think), or a host of other places on the web (like anvilfire).

CCWKen
12-14-2003, 12:13 AM
I've made special air-hammer bits and rivet sets many times. I use W-1 because it's cheap and works good. BUT... I only harden the "working face". Heat the business end to cherry/dull red and hold it there about 1-2 minutes. Feather the heat to keep it there, no more, no less. (I use an O/A torch with neutral flame.) Drop into a bucket of water. I then take it to the buffer and put a mirror shine on it. I still have everyone I've made. None have chipped or broken. I have one I use to punch 1/4 holes in car frames. Punches through in about 2 seconds with a 4X gun.

I've never done the magnet trick--I'm affraid of ruining a good magnet. (heat)

dkinzer
12-14-2003, 12:59 AM
I made some taps using W-1 drill rod. I heated them with an O/A torch until non-magnetic and then quenched in a pail of 10% brine. Then I transferred them to a pan with fresh water heated to 140* for transport to the kitchen.

I removed them from the bath and placed them directly on the oven rack where they were tempered at 350* for about 1H45M. After cooling, I cleaned them up with a wire brush and put them to work.

Don Kinzer

SGW
12-14-2003, 09:05 AM
As per BC21OSH, try to quench vertically, so the punch won't warp when you quench it.
If there's a recess in the end, you may have (hopefully minor) trouble because of trapped air.

Water just-from-the-faucet, with air in it, doesn't quench as well as water that's been sitting around a while, or boiled to drive the air out of it and cooled. A brine solution, as per dkinzer, works better than plain water.

"KeepBryte Anti-Scale Compound" (or similar) works great. MSC www.mscdirect.com (http://www.mscdirect.com) sells it. You warm the part, then dip it in the powder until the part is covered, then heat and quench. For a punch it probably doesn't matter that much unless you're trying to preseve a sharp edge; then it might help.

The magnet trick for deterimining critical temperature works very well.

Evan
12-14-2003, 10:15 AM
The Curie point for medium carbon steel is about 737C (1358F). That is the point where it loses magnetism. The correct temperature for drill rod, AKA as silver steel is 770 to 790 for water or brine quenching. The magnet test is very accurate as long as the magnet is not overheated.

See: Workshop Practice Series #1, Tubal Cain.

gizmo2
12-14-2003, 02:04 PM
One of the things I missed the boat on the first time I heat treated was; initial hardening color is IN the metal like a glow rod. The tempering color is oxidation on the surface of the metal. Once those colors start to come, they change very rapidly. I can get the light straw to gold colors in the toaster oven. Polish up the piece and bury it in a cup of silicon sand (the white stuff) and just leave a non working tip of it peaking out to monitor color. The sand will even out the heat that actually reaches the part. Then quench. I have trouble making things too soft when I'm chasing the colors with direct heat.

darryl
12-14-2003, 04:59 PM
Not touched on yet in this thread, but is there an advantage to using hardening powders with drill rod?
By the way, any cheap craft magnet will do the job of checking the steel for critical temperature. If you destroy one, no big deal, they're cheap. It doesn't need to come in contact with the steel either, just close enough to test for attraction. I doubt anyone would have a problem with the magnet. MHO

[This message has been edited by darryl (edited 12-14-2003).]

hms50
12-14-2003, 05:17 PM
And if you don't want to buy a special anti-scale compound, boric acid, available at any drugstore works very well. It is toxic so don't eat any of it!

Peter S
12-14-2003, 07:25 PM
Largely repeating what has been said, just trying to say that while heat treatment is quite specialised, you can also harden simple items at home quite well.

I was "brought up" in a place that had its own heat treating department, and almost everything we made was carefully heat treated to the correct specs.
Having moved on from there, when I have some part with a lot of machining time that requires careful heat treatment, I will send it out to get done.

Having said all that, it is amazing what you can achieve quickly and simply with a gas torch and a container of oil. (I have used anything from used engine oil to hydraulic oil).
I have made parts from silver steel and gauge plate which have worked well when hardened like this.

Wrap some wire around your part so that you can hold it while you heat it.
Using Oxy-Acetylene torch, bring it up to cherry red , then quench it. You are supposed to use water or brine for silver steel, however I quench silver steel in oil, it works fine. You get slightly lower hardness, but also less distortion using oil.
For forming tools made from gauge plate, I have used them straight after hardening, no tempering needed.
However you can polish up your part and carefully temper to straw colour, though I am a bit dubious as to its effectiveness - my silver steel spec sheet says that tempering is done for one hour, soaking at whatever temperature to give the correct resulting hardness.

However....none of my hardening was used for impact work such as rivetting, however, I would try the above simple way first.

Reelmaster
12-15-2003, 09:21 PM
Many Thanks to All who replied to my request for infomation on the Hardening Process. Greatly appreciated. You surely can learn a great amount from the many very talented people who frequent this site.
Wishing One & All a Great Xmas & New Year Holiday Season.
Best Regards. Jack. Erskine.

Dr. Rob
12-16-2003, 03:36 AM
...and the same to you, esteemed colleague of mine!

Have a good holiday and all if I don't talk to you before then. Thanks for the email; made my day!

Rob.

pgmrdan
12-16-2003, 06:55 AM
.

[This message has been edited by pgmrdan (edited 03-08-2004).]

darryl
12-16-2003, 06:32 PM
Thanks, Dan, that's pretty much what I thought, but I know there's other compounds in the powder, as well. I've heard of nitriding, and I've been told there's nitrogen oxides in the powder. I just wondered if silver steel, or drill rod, would gain something from that. I'm sure there's a limit to what can be done with any particular steel or alloy, but I know not enough about it.

Rich Carlstedt
12-16-2003, 07:52 PM
Nitriding is done in a sealed furnace, with an Ammonia atmosphere at 800 degrees.
the nitrogen is absorded by the steel for a super finish and hardness (RC 60 +)

Evan
12-16-2003, 07:53 PM
The case hardening powder is sodium ferrocyanide (Yellow Prussiate of soda). Although that sounds bad it is non-toxic unless mixed with strong acid when it will evolve free cyanide. It contains iron, sodium, nitrogen and carbon.

The process is called case hardening or carburising but it really is carbonitriding (I didn't make that up). The "case" produced contains elevated amount of carbon but also nitrogen as it is to some degree nitrided.

Treating drill rod this way would produce no benefit. Drill rod in full hard state is HRC65 and drops to HRC45 at an annealing temp of 500C. It doesn't start annealing until 100C. It's totally feasible to anneal in the home oven and is a good way to get consistent results. Clean it up good and you can also anneal in a french fry (chips) cooker. Annealing to 250C only drops the hardness to HRC60 but increases the toughness a lot.

darryl
12-16-2003, 08:21 PM
Thanks for the extra info, Evan.