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Posted: 9/12/2004 5:55:49 PM EDT
I am currently building from a flat (thus far only mucked up one; the second seems to be coming together OK), and would like to understand heat treat requirement for 4130. Previously, someone had posted a method for treating locally at the pin holes w/ a torch. I have access to a small, controlled electric furnace (used by the owner for heat treating knife blades), and would like to know what the proper heat treat schedule is, if anyone could share it.

thanks to all, especially QUIB, whose post was exceptionally helpful
Link Posted: 9/12/2004 9:06:25 PM EDT
Link Posted: 9/13/2004 6:33:44 PM EDT
Thank you, MG34.

Now, of course, as you have taken the time to offfer your experience, I am going to look the part of the typical newbie know-it-all a__hole and describe ANOTHER method I have found, which is used by a MilSpec Aerospace manufacturer.

They heat to ~1500-1600 deg F (which reaches the bright orange you referenced), and then quench in oil. (I'm curious about your experience. Oil really made a mess, eh? I'm used to quenching in oil when doing some of my hideous amateur forgings, and the flame, smoke, etc. don't bug me. Did you attempt any kind of degreasing step?)

In their case, the furnace does have an inert atmosphere, so they "soak" their parts (admittedly much thicker than an AK rcvr) for ~30 minutes.

Immediately after the quench, the part is dried off and tempered at a lower temperatore for about an hour, with the tempering heat dependent on the Rockwell hardness required by the print. Higher temperings give a lower hardness. You can get 4130 to be quite hard, but it is of course embrittled then. Seems to be we would be shooting for Rc ~ 30-35, which would be ~1000 deg F, and again 10 minutes or so would be enough owing to the thinness of the rcvr.

Finally, at the conclusion of tempering, the part is allowed to cool in still ambient air, is descaled, degreased, and sent to the next operation.

Having said all that, I'm liking your approach for all the reasons you mentioned (rapid oxidation, etc.) that I will face because I only have amateur equipment.

Perhaps I'll cut the boogered-up piece in two and try both methods to see where I end up.

Thanks again!!!
Link Posted: 9/14/2004 2:18:43 AM EDT
[Last Edit: 9/14/2004 2:34:38 AM EDT by mg34ss]
Link Posted: 9/14/2004 8:56:07 PM EDT
Can't figger out how to post the pics, but you were right -- your way looks fine and has made a tough piece, mine is wrecked and soft.

Thanks for saving me the dough on the real thing.
Link Posted: 9/15/2004 5:34:45 AM EDT
I heard that!!!! Great thread !!!!!! +1
Link Posted: 9/15/2004 4:35:59 PM EDT
I feel a little priveliged to be in the presense of these guys...

I am hoping that some of that knowledge will rub-off on me... have
Thanks Guys!
Link Posted: 9/16/2004 3:57:17 AM EDT
[Last Edit: 9/16/2004 3:59:15 AM EDT by mg34ss]
Link Posted: 9/19/2004 3:36:03 AM EDT
Good conversation. If you handle picture posting like you do steel we all would be
drooling and bowing to your RPK.
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