Phillie Ord M1a1 - Need Heat Treating?
Posted 01 May 2005 - 08:55 PM
Posted 02 May 2005 - 12:57 PM
I do believe you should make it tougher after it is fully machined, but using what heat treat - I do not want to comment on.
I have a 28 and a M1 dummy from them, they are very nice. Not Richardson quality, but very nice - certianly good enough to hang my spare parts on!
Posted 03 May 2005 - 11:21 AM
Got your message about AISI 4130 steel.
A through-hardening chromium-molybdenum steel. Common alloy grade -- used a lot. Not subject to temper embrittlement. Can be nitrided to improve surface hardness and wear resistance.
Commonly used for axles, shafts, gears, high strength fasteners, structural plate, etc.
Prior to heat treating this alloy has pretty good machinability. 70% machinability rating of AISI B1212.
Sometimes used without as is, without quenching and tempering. In this condition the material has a ultimate tensile strength of about 95ksi.
Typical heat treatment:
Heat to 1600 deg F (aka, austentize)
Quench in oil
Temper to desired hardness
Hardness after quenching with vary depending on thickness and shape. Shouldn't have too much trouble through hardening the part in the 30 to 40 HRC range. This harness equates to an ultimate tensile strength of 138 to 182ksi.
You may have some distortion from heat treating. Depends on shape. In practice this means you might need to do some finish grinding to final dimensions.
To improve surface hardness and wear resistance the alloy can be nitrided.
If the as received condition of the materials, i.e., 95ksi were adequate, you would also have the benefit of not worrying about heat treatment distortion. Additionally, the material in the as-received condition would have excellent toughness.
I feel his general comment is the key. 95ksi tensile strength seems quite adequate to me.....
Posted 04 May 2005 - 10:00 PM
I am leaning the same direction. I wish there was more data available on this subject to validate this.
Posted 04 May 2005 - 11:28 PM
I can't quote the specs for you but I can tell you that the 1928A1 I built from a Phila Ord dummy receiver has fired about 4 or 5000 rds so far and the only wear I can find is the bluing on the top of the receiver where the actuator rubs on it. It has had no heat treat and I don't think it needs it for this application. I believe the material he uses is 4130 normalized which is about 22 on the rockwell C scale. I've had similar stuff heat treated and unless you have jigs to hold it in the oven it will warp and move. On some stuff this is not a big deal as you make allowances for grinding etc but on these babys its not simple. When you look at all the other .45 SMG's out there like the grease guns I think you can see that ultra high strength is not necessary. The tommies have lots of surface area in contact on the wear parts which keeps the point loading down and with a little oil it keeps the wear down too. Just my opinion but I don't think you need to heat treat.....
Posted 05 May 2005 - 07:55 AM
Posted 05 May 2005 - 05:57 PM
...don`t mean to spoil this thread....very good info here...thanks for posting all the details.I`m involved in building a MG42 receiver and have faced the same questions...