12L14 Steel For Cannons

[Soot]

I ordered some 12L14 steel for making tools and fixtures etc, and was wondering if it would be any good for cannons.
I'm not sure how to interpret the properties but it says it's "generally" stronger than 1018. Here.
It's from Laurel Steel, Cutter's Choice.

12L14 free machining steel
This alloy has lead added to the mix in order to enhance its machinability. In fact, it is rated with a machinability of 160% of AISI 1212 steel. The addition of lead does, however, reduce the strength of this alloy, although it is generally stronger than 1018.

12L14 free machining steel
Minimum Properties    Ultimate Tensile Strength, psi    78,300
Yield Strength, psi    60,200
Elongation    10.0%
Rockwell Hardness    B84
Chemistry    Iron (Fe)    97.91 - 98.7%
Carbon (C)    0.15% max
Manganese (Mn)    0.85 - 1.15%
Phosphorus (P)    0.04 - 0.09%
Lead (Pb)    0.15 - 0.35%
Sulfur (S)    0.26 - 0.35%

Any thoughts on the matter?

[rifleshooter2]

I have been using it in my handgonnes for a long time now with out any problems.

Andy

[Double D]

George will know more about this, but isn't there an issue with weldability of leaded steels

[GGaskill]

Because the steel mill cannot control the actual location of the lead particles when making and rolling leaded steel, there is a possibility that the lead can become oriented such that it presents weak portions to the bore interior that could lead to failures as great as bursts.  It is my understanding that the lead is not molecularly dispersed, that is, the lead remains in veins of lead that get spread thorough the piece of steel in unpredictable ways.  When those veins cross the bore, they are exposed to bore chemistry and bore pressures, both of which can cause cracks perpendicular to the bore and parallel to the bore.  This may not be a problem at black powder pressures, but it is a serious risk in smokeless powder arms.  See this analysis of a burst M1A barrel for further information regarding cracks, as clearly no one is using leaded steel for smokeless barrels to my knowledge.

I have made Tannenberg gonnes from both 1018 and 12L14; the 12L14 was significantly easier to machine, and consequently gave a better as machined finish.  The Tannenberg design is quite a bit more robust than a typical smokeless powder rifle barrel so I am not much concerned about it.  I do think the use of 12L14 poses a greater risk, in spite of its slightly better physical characteristics, compared to 1018.  How much risk I cannot quantify, though clearly, the less robust the barrel design, the higher the risk.

And, yes, leaded steels weld with difficulty or worse because the lead gets boiled out of the metal.

[Cat Whisperer]

Leaded steels are great for turning!  

HOWEVER, look at the Charpy notch test data.  When you repeatedly stress the tube by firing you harden it.  1018 and others withstand this VERY well.  So it may be a bit stronger but it's resistance over time is not favorable for this application.  Use it ONLY for golf-balls - in other words VERY low pressure applications.  Failure will occur somewhere down the road - with no warning.

I could not, in good conscience, use it for something that could be used for shooting anything heavier than a golf-ball.

[Double D]

Leaded steels are great for turning!  

HOWEVER, look at the Charpy notch test data.  When you repeatedly stress the tube by firing you harden it.  1018 and others withstand this VERY well.  So it may be a bit stronger but it's resistance over time is not favorable for this application.  Use it ONLY for golf-balls - in other words VERY low pressure applications.  Failure will occur somewhere down the road - with no warning.

I could not, in good conscience, use it for something that could be used for shooting anything heavier than a golf-ball.

And to carry Tim's warning one step further, never build a connon for how you will shoot it, build it for how the next guy may shoot it

[Soot]

I guess I'll save it for making screws and stuff.
That M-1A failure is outrageous, wish I never sold mine.

[seacoastartillery]

     We use a lot of 12L14 leaded steel for making rifle bolts.  It's the closest thing you can buy to duplicate the malleable characteristics of wrought iron which was superior to cast iron in the 1860s as a rifle bolt material.  Like everyone says, it's beautiful to machine and allows you to use large form tools on the engine lathe to save time when making sabots or bolts for rifled cannon.  Below is a bolt which penetrated 1" of boiler plate.  We over-hardened the S-7 tool steel bolt a bit at 57 on the Rockwell 'C' scale, but live and learn.  You can see how well the 12L14 sabot took the Brooke rifling though.  That little cup base sabot flared out perfectly upon discharge to engage the rifling securely.  Next time it's 52 Rc for the bolt!

     However, we will Never make a cannon tube from 12L14 steel for the reasons others have stated.

Tracy and Mike

Next time we will use a triangle pattern for locking the sabot and bolt to resist unequal rotation.  We created a plain of weakness by having two pins and the central bolt all in the same plane.  It fractured along this plane.  Were we surprised?  No.  

[GGaskill]

...wish I never sold mine.

You can still buy M1's, and they're not all that different.  CMP.

[Cat Whisperer]

...wish I never sold mine.

You can still buy M1's, and they're not all that different.  CMP.

A friend of mine often has said, "Guns are meant to be bought."   (Note the PERIOD.)

[GGaskill]

I have sold only one gun that I originally bought for myself (because I had very little money at the time and was upgrading) and I would still prefer to have that one in my possession.

[Terry C.]

I remember every gun I've ever sold and regret each and every sale.

[Cat Whisperer]

My wife and I have a great working relationship - I NEVER question how many dolls she has, she reciprocates about guns.    Life is GOOD!



I wish I had as many guns as she has dolls!

[Soot]

I had a woman ask me once how many guns I needed.
I told her to go through my guns and get rid of the ones she didn't think I needed and that while she was doing that, I would go through her jewelry and get rid of the stuff I didn't think she needed.
That shut her up.