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9/22/2017 12:11:25 AM
Posted: 6/21/2005 10:09:26 PM EDT
TEMPILAQ the holes and heat to 1600 degrees. The metal should lose all magnetism and no longer attract a magnet. If using a Tempilstik, the heat has been reached when the stik starts to run.

Quench in sand (or ash or dirt) and allow to cool - kitty litter works too. (metal now annealed)

TEMPILAQ the holes and heat to 750 degrees.

Quench in oil (motor oil)... this may start an oil fire, so be prepared w/sand, lid on container, etc. (metal now tempered)


http://pookieweb.dyndns.org:61129/AK/docs/construction/heattreat.htm

Pookie's website basically says to heat up red hot and let cool down slow, then heat up to the blue color then quench.

The instructions that I have gotten with my receiver flat says to heat up red hot and quench, then heat up until blueish then slow cool. This is basically opposite of what Pookie says.

Which one is the right one?
Link Posted: 6/22/2005 4:06:18 PM EDT
The instructions you received are correct.

Pookie's website is also correct, in that, if you heat the metal to 1600 degrees and allow it to cool slowly, it will become "annealed". The problem here is that "annealed" (dead soft) is not what you're after. What you're wanting to do is to "harden" the steel around the holes so that the metal will wear better.

In order to harden steel, you first heat it, red-hot, and then rapidly quench it in oil or cold water. (I personally prefer water.) This leaves the metal in a state that is "file-hard", somewhere in the Rockwell hardness range of 60-70, depending on the type of steel. In this hardness range, the holes would wear forever, but the steel will also have become brittle (just like a file) and will be subject to break-out under impact loading. The steel around the holes has also much become much harder than the pins which are passing through them. This excessive "hardness" would cause the pins themselves to wear much quicker than they normaly should.

The process of removing this "excess" hardness is called "tempering" and it is intended to restore "flexability" to the metal while still leaving it in a semi-hardened state. Heating the metal around the holes, untill it turns a blueish/purple color, and then allowing it to slowly air cool will reduce the Rockwell hardness of the steel down into the 40-50 range (about the hardness of a good knife blade) and will greatly reduce the "brittleness" factor of the metal.

Polishing the metal around the holes, to a mirror finish, prior to the tempering stage, will allow you to more accurately see the delicate color changes in the steel.

HTH . . . . . Doug
Link Posted: 6/22/2005 5:02:34 PM EDT
In Pookie I trust.
Link Posted: 6/22/2005 6:02:29 PM EDT
Not to knock Pookie because his site is truly awesome, but just because it's written with other authoritative information doesn't mean it's correct. Tons of geniuses have been dead wrong. I follow all his other advice, but I won't use his method of heat treating anytime soon. Perhaps he could put the other directions on his site? That's the true sign of a genius...
Link Posted: 6/23/2005 7:59:55 AM EDT
What Doug said.

This section of Pookies site is a bit off from established practice.

Heat to 1600 then water quench

Heat to 700 then allow to air cool

This is for 4130 steel (tapco flats & most blanks) and has been confirmed with a Rockwell hardness tester. Other methods, including oill quench, did not produce the desired results. There is a good deal of info on theis at gunco.net.
Link Posted: 6/25/2005 8:25:22 AM EDT
I altered that info based on what a "machinist of 20 years" told me. I had it the other way around to begin with, then he "corrected" me. I've read some more info recently that confirms what others have said, that my steps are reversed. Note to self- I'm going to edit that info today to reverse those steps back around to the way I had them before.

Thanks for noting that!!!
Link Posted: 6/25/2005 3:36:40 PM EDT
So if on the first heating I go cherry red and quench and on the second go blue and air cool, I should be good?

Also, just quench in any motor oil?

Will any propane plumbers torch get the metal to this temp?
Link Posted: 6/25/2005 5:05:48 PM EDT
[Last Edit: 6/25/2005 5:08:36 PM EDT by harley_nut]
Quenching in oil will add carbon to the metal - water doesn't. Oil also doesn't have the thermal transfer characteristics of water.

For hardening receivers, you should use water.
Link Posted: 6/25/2005 5:56:01 PM EDT
Yes, use water. I didn't keep the link, but both oil and water quenched flats were tested with a Rockwell hardness tester and the oil did not produce adequate hardness. Supposedly it cools too slowly.
Link Posted: 6/26/2005 7:23:18 AM EDT
I agree. Cherry red, quench in water, blue and slow cool is standard procedure.
Link Posted: 6/26/2005 8:25:07 AM EDT
So Pookie is a genius! I'm impressed.
Link Posted: 6/26/2005 9:38:33 AM EDT
[Last Edit: 6/26/2005 9:38:54 AM EDT by HC_Pookie]
Nah, I'm NOT a genius - just way too much time on my hands for this hobby!

Technically, you should make 3 heatings: 1) normalize/anneal; 2) to austentize; 3) to temper. In short, you make it soft (anneal), then make it brittle (austentize), then stress releive (temper). That said, I think this application of sheet steel receivers does not need to be normalized. There's more in the Machinist Handbook, which I've seen for sale at Barnes & Noble. Next time I'm in the bookstore I'll be sure to verify those temperatures. The ASM site wants to show that info to members only...

I would add there is some data to suggest a salt water quench is recommended. Look around, there's tons of links about it WRT knife making & general metal work. Apparently the thicker the part, the more they recommend oil. Too fast quenching (in water) can cause brittleness and cracking. All of that data is in reference to knife making. The thin material for receivers should in theory be thin enough to remove the heat before structural damage. There just isn't enough material to hold heat long enough for cracking, but in theory it could still happen in a pure water quench.

There are some posts here-and-there to say that you need oil (ATF is recommended) due to the thermal conductivity of oil vs. water. Again, dealing with thicker materials (1/4" and thicker).

www.admiralsteel.com/reference/physical.html

www.matweb.com

www.anvilfire.com/FAQs/heat_faq_index.htm

www.bladeforums.com/forums/printthread.php?t=295736

www.rebrookforge.com/carbon.htm

www.knifenetwork.com/forum/archive/index.php/t-23139.html

A few quotes from that last link. Note the reference to metal fatigue with water quench. 4145 is the same alloy as 4130, albeit witha different carbon content:

"Austenitize at 1550-1600F, hold for at least 1 hour AT TEMPERATURE. Oil quench. Note: I have water quenched 4145 many times in heavy sections. It either works extremely well or you get your part back in pieces. Temper at 350-400F for an hour AT TEMPERATURE. Allow about 1 hour per inch of thickness just to get the part up to temperature. Now then, assuming you don't have a furnace to do this in, you may want to try flame hardening it. Find a welding shop or heat treat shop that knows how to do this and you can get an Rc50 case on it with fairly tough undercase."

"To heat treat a 4140 blade use the same temperatures but scale back the time. Normal hold times are designed to allow the heat to penetrate thick sections so if you have only a 1/4" section, reduce the hold time to 15-20 minutes. If the 4140 has been annealed, you may want to increase the hold to 45-60 minutes to dissolve the carbides. Oil quenching of blades is highly recommended. I have done it in water but it is very risky and distortion is almost always a problem. I have actually used compressed air to quench 4140 but I do not think this will achieve the best hardness."

hth,
- Jerry
Link Posted: 9/19/2005 5:33:25 AM EDT
What is the general oppinions of those here on tempering the ejector? I have seen posts from guys in the past that indicate that they do not temper the ejector and they have not had an ejector break and god knows these ejectors take a pounding fron steel cases...

I think my last build I did temper my ejector but I don't have a good feeling on where most guys sit on this...
Link Posted: 9/19/2005 6:31:57 AM EDT
[Last Edit: 9/19/2005 9:36:34 AM EDT by dalesimpson]
I did my first couple of builds without heat treating the ejectors. I went back and filed off the peening and hardened them later after the ejectors started to deform. I just heat the ejector to a kind of straw yellow color, quench in water, then heat until blue and allow to air cool. Since I have been using this method, I have no deformation of any of my ejectors even after several hundred rounds.

edited to replace the word "tempering" with "heat treating"
Link Posted: 9/19/2005 9:08:46 AM EDT

Originally Posted By dalesimpson:
I did my first couple of builds without tempering the ejectors. I went back and filed off the peening and hardened them later after the ejectors started to deform. I just heat the ejector to a kind of straw yellow color, quench in water, then heat until blue and allow to air cool. Since I have been using this method, I have no deformation of any of my ejectors even after several hundred rounds.



So, you are saying that you got peening when you didn't temper so now you temper?

I have to heat treat a receiver tonight and I guess I will temper the ejector as it seems most guys do...
Link Posted: 9/19/2005 9:37:40 AM EDT

Originally Posted By Quarterbore:

Originally Posted By dalesimpson:
I did my first couple of builds without tempering the ejectors. I went back and filed off the peening and hardened them later after the ejectors started to deform. I just heat the ejector to a kind of straw yellow color, quench in water, then heat until blue and allow to air cool. Since I have been using this method, I have no deformation of any of my ejectors even after several hundred rounds.



So, you are saying that you got peening when you didn't temper so now you temper?

I have to heat treat a receiver tonight and I guess I will temper the ejector as it seems most guys do...



I meant to say "heat treating", although tempering is part of heat treating. The problems I had were on Tapco rails, the rails I have gotten lately from DPH Arms have all heat treated ejectors.
Link Posted: 9/19/2005 7:46:46 PM EDT
[Last Edit: 9/19/2005 7:48:16 PM EDT by Bob1984]
What do you usually use to heat the receivers with and where do you get it from ? How do you hold it (what do you use for securing the receiver) for quenching without deforming the metal ? Sorry for the really obvious, newbie-type questions. ETA: are the thicker .064 blanks that much harder to build on than the standard .040 ?
Link Posted: 9/19/2005 11:03:25 PM EDT

Originally Posted By dalesimpson:

Originally Posted By Quarterbore:

Originally Posted By dalesimpson:
I did my first couple of builds without tempering the ejectors. I went back and filed off the peening and hardened them later after the ejectors started to deform. I just heat the ejector to a kind of straw yellow color, quench in water, then heat until blue and allow to air cool. Since I have been using this method, I have no deformation of any of my ejectors even after several hundred rounds.



So, you are saying that you got peening when you didn't temper so now you temper?

I have to heat treat a receiver tonight and I guess I will temper the ejector as it seems most guys do...



I meant to say "heat treating", although tempering is part of heat treating. The problems I had were on Tapco rails, the rails I have gotten lately from DPH Arms have all heat treated ejectors.



You sure the DPH ejectors are treated ? Says on the website that they're not.
Link Posted: 9/19/2005 11:16:11 PM EDT
DPH ejectors used to be heat treated but not anymore.
Link Posted: 9/20/2005 3:58:09 PM EDT
[Last Edit: 9/20/2005 3:59:41 PM EDT by Hammer in PA]
I use Kasenit on the FCG holes and the ejector, no egging of the holes and no damage to the ejector.

However, Kasenit leaves the metal hard and one time when I was trying to bend the ejector (it wasn't spot welded in yet) and the thing cracked. I did use a little to much force and this was in my early days of building.

I still use Kasenit but I don't try to bend anything that was hardened.



Link Posted: 9/20/2005 4:04:57 PM EDT
Thanks... Any time I had seen ejectors hardened it was after the rails were welded fast so you could check the alignment and make any adjustments...

I did my AMD-65 Heat Treat tonight and I had a tough time seeing the color change on the ejector... So, I heated it up to where I figured it should have started to go blue and called it a day....

Tonight I hope to press in the barrel and headspace....
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