Burning powder temp?

GASCHECK · September 9, 2009, 09:39 PM

Loaders:

And that's just what I'm asking. Say for the .45 Auto cartridge.

Thanks! Gascheck

IllinoisCoyoteHunter · September 9, 2009, 09:56 PM

810.93 Kelvin

Just a guess though...

GASCHECK · September 9, 2009, 11:40 PM

That's about a thousand degrees, according to an online conversion site.
Gotta be much hotter than that, I would think . .

Gascheck

snuffy · September 10, 2009, 02:16 AM

Burning where, inside a rifle cartridge, or out in the open on my sidewalk?

Jim Watson · September 10, 2009, 07:32 AM

Flame temperature of smokeless powder is about 2700 F when burning properly in the chamber. Less when unconfined, but I don't have a number for that.

**Unclenick** · September 10, 2009, 08:14 AM

That's about right, depending on powder brand, except the units should be °C. Its about 2775°C (3050 K) in the chart below, or almost 5000°F (5487°R). I remember 20 years or so ago, Winchester had ads bragging their Ball® powders burned at a lower temperatures than conventional stick powders for better barrel life. Their example claimed 5000°F for conventional stick powder and 4500°F for their powder, IIRC?

I have no faith in memories that old, so I poked around until I found the below temperature chart from a U.S. Army Research Lab study of ceramic "nozzles" (actually throat inserts) for extending barrel life. That study is here, if you're interested? They use a 37 mm chamber for testing. The introduction explains that modern propellants can shoot out some barrels in as little as 174 rounds. Presumably those are bigger guns than most of us shoot, probably ones on their 37 mm test bed, and it is the reason they were interested in the inserts. You can see from the long time frame that this chart plots a really slow powder, where most of what we shoot in small arms will find a peak pressure and temperature in half a millisecond. However, that leads to the temperatures and pressures peaks being similar for the two circumstances, after you scale it all.

Some astute reader will no doubt realize those temperature peaks are about twice the melting point of steel. Not to worry. The study includes some rather festive looking differential equations describing the temperature difference normal (perpendicular) to a chamber or bore surface. This is a fancy way of saying there is a temperature gradient between the surface and the hottest part of the gas. That happens because the steel has much higher specific heat than the gas, so it cools the gas at its surface more than the gas can raise its temperature. Nonetheless, you do get a couple thousandths of an inch of heat penetration into the steel that raises its temperature enough to expand it significantly, and that rapid surface expansion, while the base metal underneath is not expanded, causes those alligator skin looking cracks you see in borescope photos of well-used throats.

GASCHECK · September 11, 2009, 12:30 AM

Thank you gentlemen.

Gascheck

September 9, 2009, 09:39 PM	#1
GASCHECK Senior Member Join Date: June 18, 2004 Posts: 218	Burning powder temp? Loaders: And that's just what I'm asking. Say for the .45 Auto cartridge. Thanks! Gascheck

September 9, 2009, 09:56 PM	#2
IllinoisCoyoteHunter Senior Member Join Date: December 23, 2008 Location: Southern Illinois Posts: 1,527	810.93 Kelvin Just a guess though... __________________ ~~IllinoisCoyoteHunter~~ ~NRA LIFE MEMBER~ ~NRA CERTIFIED INSTRUCTOR~

September 10, 2009, 02:16 AM	#4
snuffy Senior Member Join Date: May 20, 2001 Location: Oshkosh wi. Posts: 3,055	Burning where, inside a rifle cartridge, or out in the open on my sidewalk? __________________ The more people I meet, the more I love my dog They're going to get their butts kicked over there this election. How come people can't spell and use words correctly?

September 10, 2009, 08:14 AM	#6
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,061	That's about right, depending on powder brand, except the units should be °C. Its about 2775°C (3050 K) in the chart below, or almost 5000°F (5487°R). I remember 20 years or so ago, Winchester had ads bragging their Ball® powders burned at a lower temperatures than conventional stick powders for better barrel life. Their example claimed 5000°F for conventional stick powder and 4500°F for their powder, IIRC? I have no faith in memories that old, so I poked around until I found the below temperature chart from a U.S. Army Research Lab study of ceramic "nozzles" (actually throat inserts) for extending barrel life. That study is here, if you're interested? They use a 37 mm chamber for testing. The introduction explains that modern propellants can shoot out some barrels in as little as 174 rounds. Presumably those are bigger guns than most of us shoot, probably ones on their 37 mm test bed, and it is the reason they were interested in the inserts. You can see from the long time frame that this chart plots a really slow powder, where most of what we shoot in small arms will find a peak pressure and temperature in half a millisecond. However, that leads to the temperatures and pressures peaks being similar for the two circumstances, after you scale it all. Some astute reader will no doubt realize those temperature peaks are about twice the melting point of steel. Not to worry. The study includes some rather festive looking differential equations describing the temperature difference normal (perpendicular) to a chamber or bore surface. This is a fancy way of saying there is a temperature gradient between the surface and the hottest part of the gas. That happens because the steel has much higher specific heat than the gas, so it cools the gas at its surface more than the gas can raise its temperature. Nonetheless, you do get a couple thousandths of an inch of heat penetration into the steel that raises its temperature enough to expand it significantly, and that rapid surface expansion, while the base metal underneath is not expanded, causes those alligator skin looking cracks you see in borescope photos of well-used throats. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle Last edited by Unclenick; September 10, 2009 at 08:49 AM. Reason: typo fix and addition

September 9, 2009, 11:40 PM	#3
GASCHECK Senior Member Join Date: June 18, 2004 Posts: 218	That's about a thousand degrees, according to an online conversion site. Gotta be much hotter than that, I would think . . Gascheck

September 10, 2009, 07:32 AM	#5
Jim Watson Senior Member Join Date: October 25, 2001 Location: Alabama Posts: 18,539	Flame temperature of smokeless powder is about 2700 F when burning properly in the chamber. Less when unconfined, but I don't have a number for that.

September 11, 2009, 12:30 AM	#7
GASCHECK Senior Member Join Date: June 18, 2004 Posts: 218	Thank you gentlemen. Gascheck