Heat Treating

XLT · April 9, 2005, 09:16 AM

Anyone here used a blacksmith forge to heat treat a stamped receiver?

Seems like the natural gas versions would be able to maintain a constant temperature, and they're cheaper (and reach temperature faster) than a kiln.

TIA,

XLT

mete · April 9, 2005, 12:37 PM

You want to heat treat a receiver ??? What receiver and why ?

XLT · April 9, 2005, 01:08 PM

an 80% AK receiver for a kit build is what I had in mind.

steveno · April 9, 2005, 01:12 PM

there is a lot more to heat treating than that. first of all heat treating is done in a special oven that is generally computer controlled and not a forge.

XLT · April 9, 2005, 01:24 PM

Thanks, but I wasn't really looking for someone who hasn't done it, to tell me it can't be done...

The question was has anyone done it, and if you have, how did you maintain the temperature.

I know a propane forge is capable of achieving adequate temperature, just looking for means to maintain proper draw down temperature.

mete · April 9, 2005, 02:09 PM

Before you start - what type of steel is it made of , is it case hardened, what are you trying do to it ,what type of hardness are you looking for ,etc etc ????? If you don't know the answers to these questions don't even start.

XLT · April 9, 2005, 02:25 PM

There we go...I take back all the stuff I've ever said about New Yorkers

.

It is 4130 carbon steel, a standard flat from Tapco, not case hardened. If I can harden it in a forge, I will be purchasing with a couple of buddies, the bending jig from DPH. The target hardness is Rockwell 42. I am hoping to use a relatively small propane forge, similar to those used by farriers or knifemakers.

I have gotten mixed info regarding the requisite technique. Most seem to agree that that it requires a temperature of 1600 F quenched in oil. Then a draw down period of one hour, and air cool. Some people say 600, others 900 for the draw down.

Blacksmiths say they can judge these temperatures by sight (color of steel). However, I am not a blacksmith...thus the need for input on determining and maintaining the correct draw down temperature.

Thanks,

XLT

Harry Bonar · April 9, 2005, 02:46 PM

Dear Sir:
As these other smiths have said there is much you need to know before even thinking about heat treating 4130.
First of all, this is an alloy steel - meaning it will heat treat homogeniously (all the way through) there is no need to add carbon in "carburizing" or, "case hardening."
Alloy steels do not "case harden" very well!
First, you need from the manufacturer (they supply this info) the decalescence point; then how long you leave it at that temp (we harden on a rising heat at the decaslescence temp where the carbon undergoes a chemical change and the steel becomes non-magnnetic.)
Then, you need to know the quenching medium, and what temp' it needs to be - then you cannot guess at the "tempering" temp' - it must be known positively. And, more to the point you need a Rockwell tester to certify the hardness.
I sincerely think that these considerations have not been addressed. My best to you.
Harry B.

cntryboy1289 · April 9, 2005, 02:49 PM

Find out from the steel manufacturer about the hardening temps, quinching needed and the draw temps and their soaking times. I would then try to find a knife maker who has the oven and let him have the info and let him do the work for you if you don't have acces to the material to build your own. I would suggest going to the library and finding some books on metalurgy as well as one on knife making. The knife making book should have plans in it for building the furnace as well as might have the proper soak temps and times for the steel you need. Become as knowledgable as possible on heat treating before you even think about building the furnace. It isn't something for the average joe to undertake without the knowledge and a good furnace. You don't have to have a computer controlled furnace to do the job. A good fire brick furnace that is sealed well and has a good thermometer can do the job if you know the soak times and the quinching material needed. I would buy some of the same material as the reciever is made of and do some practicing first. Cut it into different pieces and then heat treat them and have them checked for the hardness you need for the reciever. A little prep like this will let you know if you are capable of doing the job. Make sure and have it checked all over the practice pieces and not in just one spot. Have them tensile tested for strength as well. When you get to where you can do it over and over without failure, then it's time to try the reciever out. This is a very serious proposition, one not to be taking lightly since your life could be on the line. If you feel like you are up to it, go for it. As long as you practice it and have the pieces tested so you know if the process is working, you should be able to turn out a decent job. Good luck and come back and tell me what you decide.

XLT · April 9, 2005, 03:07 PM

Now that was helpful information! Thank you gentlemen for your input.

brickeyee · April 9, 2005, 04:05 PM

You can use temp crayons to monitor the surface temp. They are marked on the surface and melt at known points. The problem with anything but an oven is that it is very dificult to get a uniform temperature that can be controlled well enough to ensure correct soaking, without overheating smaller section portions of the object.

mete · April 9, 2005, 04:34 PM

Harry B, alloy steels are case hardened regularly -4320,4620,8620.3310 etc .....4130 - harden from 1600F, quench in warm[140F] oil, temper about 600F.Use a furnace [with thermocouple ]not an open fire.

Harry Bonar · April 11, 2005, 06:57 AM

Dear Sir:
I didn't say they couldn't be carburized. I said it didn't work very well - generally low to medium carbon steels are case-hardened - alloy steels are case hardened generall for appearance as you can get any hardness you want from the steels you mentioned.
I am suspicious about case hardening alloy steels.
This is bourne out buy several heat-treating manuals - and - by the warpage that someytimes occurs in alloy steels.
I WOULD NOT carburize any alloy steel action used in a high pressure (45,000 - 50,000) action!
If I did carburize an alloy steel it would be done by an old established firm, with a full lab - probably in England - we must be careful in heat treating ANY firearm part, let alone an action; as I've said before, NO ONE knows how exactly the Germand or Czechs' heat treated their actions - leave them alone - if there is set-back junk it!
Good shooting Harry B.

mete · April 11, 2005, 07:14 AM

Harry, 'suspicious' about case hardening ? I'll bet your car's wheel bearings are case hardened alloy steel , you better walk !!....The Mauser actions where carbon steels that were case hardened.My M98 has been reheat treated because you should never trust them to not be soft and 'set back'. There are companies here that do it regularly...Today we typically use 4140 [chrome-moly] steel for receivers which are not case hardened. They are through hardened to 35-40HRc.....I have no idea of the details of the project so couldn't advise about warpage etc.

Harry Bonar · April 11, 2005, 04:14 PM

DEAR sir:
I'll stand on my remarks --
Sincerely & best wishes Harry B.

April 9, 2005, 09:16 AM	#1
XLT Senior Member Join Date: January 20, 2005 Location: El Paso, TX Posts: 207	Heat Treating Anyone here used a blacksmith forge to heat treat a stamped receiver? Seems like the natural gas versions would be able to maintain a constant temperature, and they're cheaper (and reach temperature faster) than a kiln. TIA, XLT

April 9, 2005, 01:24 PM	#5
XLT Senior Member Join Date: January 20, 2005 Location: El Paso, TX Posts: 207	Thanks, but I wasn't really looking for someone who hasn't done it, to tell me it can't be done... The question was has anyone done it, and if you have, how did you maintain the temperature. I know a propane forge is capable of achieving adequate temperature, just looking for means to maintain proper draw down temperature. Last edited by XLT; April 9, 2005 at 01:59 PM.

April 9, 2005, 02:46 PM	#8
Harry Bonar Senior Member Join Date: December 5, 2004 Location: In the Vincent, Ohio general area. Posts: 1,804	Heat Treating Dear Sir: As these other smiths have said there is much you need to know before even thinking about heat treating 4130. First of all, this is an alloy steel - meaning it will heat treat homogeniously (all the way through) there is no need to add carbon in "carburizing" or, "case hardening." Alloy steels do not "case harden" very well! First, you need from the manufacturer (they supply this info) the decalescence point; then how long you leave it at that temp (we harden on a rising heat at the decaslescence temp where the carbon undergoes a chemical change and the steel becomes non-magnnetic.) Then, you need to know the quenching medium, and what temp' it needs to be - then you cannot guess at the "tempering" temp' - it must be known positively. And, more to the point you need a Rockwell tester to certify the hardness. I sincerely think that these considerations have not been addressed. My best to you. Harry B.

April 9, 2005, 02:49 PM	#9
cntryboy1289 Senior Member Join Date: July 19, 2004 Location: Ms Posts: 1,160	check with the steel manufacturer first Find out from the steel manufacturer about the hardening temps, quinching needed and the draw temps and their soaking times. I would then try to find a knife maker who has the oven and let him have the info and let him do the work for you if you don't have acces to the material to build your own. I would suggest going to the library and finding some books on metalurgy as well as one on knife making. The knife making book should have plans in it for building the furnace as well as might have the proper soak temps and times for the steel you need. Become as knowledgable as possible on heat treating before you even think about building the furnace. It isn't something for the average joe to undertake without the knowledge and a good furnace. You don't have to have a computer controlled furnace to do the job. A good fire brick furnace that is sealed well and has a good thermometer can do the job if you know the soak times and the quinching material needed. I would buy some of the same material as the reciever is made of and do some practicing first. Cut it into different pieces and then heat treat them and have them checked for the hardness you need for the reciever. A little prep like this will let you know if you are capable of doing the job. Make sure and have it checked all over the practice pieces and not in just one spot. Have them tensile tested for strength as well. When you get to where you can do it over and over without failure, then it's time to try the reciever out. This is a very serious proposition, one not to be taking lightly since your life could be on the line. If you feel like you are up to it, go for it. As long as you practice it and have the pieces tested so you know if the process is working, you should be able to turn out a decent job. Good luck and come back and tell me what you decide.

April 11, 2005, 06:57 AM	#13
Harry Bonar Senior Member Join Date: December 5, 2004 Location: In the Vincent, Ohio general area. Posts: 1,804	heat treating Dear Sir: I didn't say they couldn't be carburized. I said it didn't work very well - generally low to medium carbon steels are case-hardened - alloy steels are case hardened generall for appearance as you can get any hardness you want from the steels you mentioned. I am suspicious about case hardening alloy steels. This is bourne out buy several heat-treating manuals - and - by the warpage that someytimes occurs in alloy steels. I WOULD NOT carburize any alloy steel action used in a high pressure (45,000 - 50,000) action! If I did carburize an alloy steel it would be done by an old established firm, with a full lab - probably in England - we must be careful in heat treating ANY firearm part, let alone an action; as I've said before, NO ONE knows how exactly the Germand or Czechs' heat treated their actions - leave them alone - if there is set-back junk it! Good shooting Harry B. Last edited by Harry Bonar; April 11, 2005 at 06:59 AM. Reason: terms

April 9, 2005, 12:37 PM	#2
mete Senior Member Join Date: June 14, 2004 Location: NY State Posts: 6,575	You want to heat treat a receiver ??? What receiver and why ?

April 9, 2005, 01:08 PM	#3
XLT Senior Member Join Date: January 20, 2005 Location: El Paso, TX Posts: 207	an 80% AK receiver for a kit build is what I had in mind.

April 9, 2005, 01:12 PM	#4
steveno Senior Member Join Date: June 18, 2004 Location: Minden , Nebraska Posts: 1,407	there is a lot more to heat treating than that. first of all heat treating is done in a special oven that is generally computer controlled and not a forge.

April 9, 2005, 02:09 PM	#6
mete Senior Member Join Date: June 14, 2004 Location: NY State Posts: 6,575	Before you start - what type of steel is it made of , is it case hardened, what are you trying do to it ,what type of hardness are you looking for ,etc etc ????? If you don't know the answers to these questions don't even start.

April 9, 2005, 02:25 PM	#7
XLT Senior Member Join Date: January 20, 2005 Location: El Paso, TX Posts: 207	There we go...I take back all the stuff I've ever said about New Yorkers . It is 4130 carbon steel, a standard flat from Tapco, not case hardened. If I can harden it in a forge, I will be purchasing with a couple of buddies, the bending jig from DPH. The target hardness is Rockwell 42. I am hoping to use a relatively small propane forge, similar to those used by farriers or knifemakers. I have gotten mixed info regarding the requisite technique. Most seem to agree that that it requires a temperature of 1600 F quenched in oil. Then a draw down period of one hour, and air cool. Some people say 600, others 900 for the draw down. Blacksmiths say they can judge these temperatures by sight (color of steel). However, I am not a blacksmith...thus the need for input on determining and maintaining the correct draw down temperature. Thanks, XLT

April 9, 2005, 03:07 PM	#10
XLT Senior Member Join Date: January 20, 2005 Location: El Paso, TX Posts: 207	Now that was helpful information! Thank you gentlemen for your input.

April 9, 2005, 04:05 PM	#11
brickeyee Senior Member Join Date: December 29, 2004 Posts: 3,351	You can use temp crayons to monitor the surface temp. They are marked on the surface and melt at known points. The problem with anything but an oven is that it is very dificult to get a uniform temperature that can be controlled well enough to ensure correct soaking, without overheating smaller section portions of the object.

April 9, 2005, 04:34 PM	#12
mete Senior Member Join Date: June 14, 2004 Location: NY State Posts: 6,575	Harry B, alloy steels are case hardened regularly -4320,4620,8620.3310 etc .....4130 - harden from 1600F, quench in warm[140F] oil, temper about 600F.Use a furnace [with thermocouple ]not an open fire.

April 11, 2005, 07:14 AM	#14
mete Senior Member Join Date: June 14, 2004 Location: NY State Posts: 6,575	Harry, 'suspicious' about case hardening ? I'll bet your car's wheel bearings are case hardened alloy steel , you better walk !!....The Mauser actions where carbon steels that were case hardened.My M98 has been reheat treated because you should never trust them to not be soft and 'set back'. There are companies here that do it regularly...Today we typically use 4140 [chrome-moly] steel for receivers which are not case hardened. They are through hardened to 35-40HRc.....I have no idea of the details of the project so couldn't advise about warpage etc.

April 11, 2005, 04:14 PM	#15
Harry Bonar Senior Member Join Date: December 5, 2004 Location: In the Vincent, Ohio general area. Posts: 1,804	heat treating DEAR sir: I'll stand on my remarks -- Sincerely & best wishes Harry B.