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Discussion Starter · #1 ·
i got a piece of solid 1045 steel its about 28" long and 3'dia thought about a howitzer style barrel
was wondering if i made a bore of 1.71 golf ball size with a powder pocket 1"x3"
my worry is no the powder pocket as i have 1" material around it and more then enouf behind it but the bore walls if they be safe enouf as they will be around 3/4 or so thin
i know NSSA rules state barrel should be atleast as think as the bore
should i mkae the bore smaller or will this be ok
Even i dont belong to the NSSA i do heed there safety rules
 

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1045 has enough carbon in it to cause some folks to worry about cracking.

NO problem with golf balls. The pressure is very low compared to shooting iron/zinc/aluminum spheres.

If the steel is ductile (like 1018) it flexes and flexes and flexes.

If it's harder (which has advantage of being stronger) it is susceptable to cracking.

One engineer here used (I think) 1024 with some reservation.
 

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buzz36 said:
i got a piece of solid 1045 steel its about 28" long and 3'dia thought about a howitzer style barrel
was wondering if i made a bore of 1.71 golf ball size with a powder pocket 1"x3"
my worry is no the powder pocket as i have 1" material around it and more then enouf behind it but the bore walls if they be safe enouf as they will be around 3/4 or so thin
i know NSSA rules state barrel should be atleast as think as the bore
should i mkae the bore smaller or will this be ok
Even i dont belong to the NSSA i do heed there safety rules
The one caliber rule is the safety rule for artillery pieces used in N-SSA competitions, we refer them as safety guidelines. Now why would you want to ignore safety guidelines?

If you have the skill and knowledge you can use a different steels and make thinner walls, but to what purpose.

Some things to keep in mind.

First to comply with the Antique exemption, and especially over .50 caliber you need to be replicating a pre 1899 design muzzle loader, not just making a piece of steel with a hole down the center.

If you find a piece of steel, divided its diameter by three to determine the size of projectile.

If you have a projectile multiply it by three to and look for a piece of steel that diameter for the projectile.

Before you go to a howitzer design think about how you are going to load that chamber. It isn't easy.
 

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Using a higher carbon alloy like 1045 depends on the state of the material. If it is annealed or otherwise softened, it should give plenty of ductility.
 

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Discussion Starter · #7 ·
thanks guys im unsure if this piece has been soften i see if i can find out
I like the idea of a solid piece into a barrel vs cast iron with a liner tube
 

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In my past I did some preheated weld cladding to build a few of the diameters on a BOFORS 40mm. Recently sent it to Denver and had it "cooked" or stress relieved prior to my machining. Hardness and uneven stress relieving (warping) while turning were my concerns. If you have any doubt about your barrel's heat treatment you can stress relieve (1200F), or anneal it (1400-1600F) or if it were an air hardening tool steel have it normalized (same as annealing but they turn off the oven and let it cool down over a few days). Like the other George says it would be good to know the "heat" condition of your shaft... for several reasons. Anything above 40 points of carbon (the last two numbers of the alloy) could be hardened, brittle and very difficult to machine and possibly too brittle for taking the firing stresses without cracking... Properly quenched and tempered 1045 should give excellent hardness, ductility and overall strength characteristics if you set the parameters of the treatment to your particular end use.

Good luck with it. My BOFORS cost me about $75 to stress relieve... and it weighs in at 110 pounds so I thought it was well worth the peace of mind regarding my own concerns.

GOW
 

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I've been meaning to ask about this for some time now; in a higher carbon steel barrel that's been annealed, wouldn't the repeated explosions work harden the steel?
I believe that there is an industrial process in which explosives are used for this exact reason, they use the shockwave to harden steel components.
I don't know if this would apply to black powder, but it would be prudent to find out.
 

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I am not familiar with the process but high explosives produce much higher pressures than black powder, probably on the order of 100 times higher. In fact, the shock wave is really what differentiates high explosives from things like black or smokeless powders which merely burn, quickly notwithstanding.

Certainly smokeless rifle pressures are two to five times black powder pressures and I have never heard of fatigue failure of rifle barrels and they are built to higher design stresses than the 1:1 ratio recommended for black powder cannon.

It might be a problem if a barrel were fired tens of thousands of times but that is unlikely.
 

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jamesbeat said:
I've been meaning to ask about this for some time now; in a higher carbon steel barrel that's been annealed, wouldn't the repeated explosions work harden the steel?
I believe that there is an industrial process in which explosives are used for this exact reason, they use the shockwave to harden steel components.
I don't know if this would apply to black powder, but it would be prudent to find out.
Yup. That's the game in the design process. KNOWING that the pressures will NEVER be just a little too high (stretching the metal, hardening it - even just a little or in one little place). With the mild steels (low carbon) the steel has the ability to stretch and recover. OK, with higher carbon steels your strength is more - but once it's hardened in a spot it will crack rather than flex. The cracks grow. AND at SOME POINT it lets go.

Our position here is to keep it safe by following recommended (by groups such as AAA and N-SSA) design principles that have been proven safe by lots of folks over lots of years.

You can get a degree in explosives forming - there's a lot to it. I'll stick to cannons and mortars of traditional design.
 

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Yes, you were right, it is high explosives that they use, low explosives or propellants wouldn't affect steel in this way.
The process is called 'shock hardening', and although it seems to be irelevant to our hobby, it makes interesting reading:
http://en.m.wikipedia.org/wiki/Shock_hardening

I wonder if other metals like bras or bronze would be affected by black powder in this way? They are a lot more prone to work hardening, and maybe it would take less force to end up with a catastrophic failure?
Aluminum barrels would certainly fail in this way.
 
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