Author Topic: Steel: What kind? (Read 2725 times)

0reo · « **on:** January 03, 2011, 09:01:10 AM »

I'm thinking about a golf ball howitzer. I'm making phone calls to see about the cost of machine shop services and raw materials prices. Machine shop tells me that stainless will be a little less expensive because 4140 or 4150 will require annealing first and heat treating after. So, stainless will probably look nicer anyway but what grade of stainless would be good for this project? Other recommendations? (I've decided against brass / bronze.)

armorer77 · « **Reply #1 on:** January 03, 2011, 10:11:33 AM »

I made 3 GB mini mortars from 304 stainless , machines easily , welds easily . Hard to beat 1018 except on clean up .

Cat Whisperer · « **Reply #2 on:** January 03, 2011, 11:52:46 AM »

Agree 100% on both 304 and 1018.

GGaskill · « **Reply #3 on:** January 03, 2011, 12:09:42 PM »

Most 4140 is either annealed or pre-hardened but machinable. It would not require post-machining heat treatment.

But 4140 is overkill for black powder artillery. 1018 is plenty good. Stainless is nice because it cleans easier for some reason.

Cat Whisperer · « **Reply #4 on:** January 03, 2011, 12:43:34 PM »

1018 has plenty of strength.

It has the resilance repeated impact without cracking - this is a feature that lots of folks miss - that make it very suitable for cannons.

0reo · « **Reply #5 on:** January 03, 2011, 01:47:20 PM »

Considering I'll be paying someone to do the machine work, easier machineability is a good thing. ($$$)

I would have done brass but after reading the kaboom thread & considering brass's tendency to work-harden I'm thinking brass may be inferior to steel if I can get it machined for a reasonable cost.

seacoastartillery · « **Reply #6 on:** January 04, 2011, 02:53:03 AM »

Just as GGaskill suggests in reply 3 above, we build all of our customer cannons from alloy steel, 4150 which has been prehardened to 28-32 Rockwell on the 'C' scale. It machines easily with carbide tools. No heat-treatment afterward is required at all. We make all of our own cannon from 1018. Just like Cat Whisperer says, it is strong, resilient and can take repeated firings without failing. It machines like butter and requires no heat-treatment either. It's less expensive too.

FYI,

Tracy

Cannoneer · « **Reply #7 on:** January 04, 2011, 05:31:41 PM »

Quote from: GGaskill on January 03, 2011, 12:09:42 PM

Most 4140 is either annealed or pre-hardened but machinable. It would not require post-machining heat treatment.

Doesn't the equation change if any welding is done on these steel alloys? Don't the 41XX alloy steel designations call for some prep before welding, and heat treatment after the welding is completed to maintain the intended properties of the metal?

GGaskill · « **Reply #8 on:** January 04, 2011, 06:42:18 PM »

Welding on 4140 calls for pre- and post-weld heating activities that really complicate the issue. If you don't need the extra strength of 4140, go with something that welds easily if welding is a requirement.

Double D · « **Reply #9 on:** January 04, 2011, 07:07:19 PM »

When the trunnion were welded on my Cairo gun-4140 HT, They preheated it. Then welded it. Then heated slightly hotter than the preheat and held the temperature for a period of time, then slowly cooled.

0reo · « **Reply #10 on:** January 04, 2011, 07:37:35 PM »

I'm thinking about 316 stainless. Looks to be stronger then 303 and 304, weldable, and machineable with carbide tools. Anyone find fault with that? (My google-fu may not be very strong.)

Cat Whisperer · « **Reply #11 on:** January 05, 2011, 07:31:51 AM »

Quote from: 0reo on January 04, 2011, 07:37:35 PM

I'm thinking about 316 stainless. Looks to be stronger then 303 and 304, weldable, and machineable with carbide tools. Anyone find fault with that? (My google-fu may not be very strong.)

Take a LONG look at the relative CHARPY Notch tests - they will tell you a lot about the particular metal's resistance to CRACKING. Compare to 1018 results for a frame of reference.

0reo · « **Reply #12 on:** January 05, 2011, 07:19:13 PM »

Thanks for that recommendation Cat Whisperer. Do you know of any link to these test results? I'm googling but not coming up with much.

Cat Whisperer · « **Reply #13 on:** January 06, 2011, 01:13:00 AM »

The short answer (I'm on my way to work) is google: steel, 1018, charpy.

More later, one has to sort through the wealth of stuff.

GGaskill · « **Reply #14 on:** January 07, 2011, 11:23:08 AM »

While surfing for more info on this general subject, I found a site that stated the ductile to brittle transition temperature (DBTT) for 1018 is 41° F which is uncomfortably high from my perspective.

So I would ask one or more of you who live in cold climates to conduct an experiment. Get yourself a piece of 1" (25mm) 1018 or equivalent (mild steel) and leave it in an area where it will get really cold (below freezing qualifies as really cold to this southern California native.) Once it is ambient temperature, take the steel to a place where you can support both ends and slam it in the middle with a heavy sledge hammer. Please report whether it bends or breaks. Thank you.

dan610324 · « **Reply #15 on:** January 07, 2011, 11:37:43 AM »

we got minus 28 here now (-16,6 F ) so I prefer to sit in here and use the computer instead

zipping some hot home made glögg and talking to my gf
thats much better than being outside
have been working a little on a mold constructin for an krucifix with jesus on it
now its just the polar beers on the street

but we are lucky to not have that much snow yet , its just 2-3 feet .

maybe its time for me to go to bed soon , I syart having problrms to find the right letters while Im typing
dont want dd to need to help me with explenating something an bad translating programme again
so good nighpt for now

Double D · « **Reply #16 on:** January 07, 2011, 11:40:50 AM »

Goerge,

Send me a piece and I will do it.

I think I have a piece of 1144 1" about a foot long, will that work?

GGaskill · « **Reply #17 on:** January 07, 2011, 11:47:35 AM »

I don't know what the DBTT of 1144 is; I will see if I can find it and let you know.

dan610324 · « **Reply #18 on:** January 07, 2011, 12:24:01 PM »

after swveral hot glögg snd an small rum azd prpsi there if no iodfg topcontinu yhis anym mkore

god natt kära vännrt nu ptttsonm sketa full nö möre writng hrer youniht

GGaskill · « **Reply #19 on:** January 07, 2011, 12:24:55 PM »

I have looked around for info on Ductile-Brittle Transition Temperature and it does not seem to be something that is listed in most materials descriptions nor is there any web-based listing of the data other than an occasional reference as part of some research paper or similar thing.

Guess we have to do our own experiments.

GGaskill · « **Reply #20 on:** January 07, 2011, 12:27:55 PM »

after swveral hot glögg snd an small rum azd prpsi there if no iodfg topcontinu yhis anym mkore
Translation: After several hot glöggs and a small rum and Pepsi, there is no ??point?? to continue this any more.

I would concur with this assessment.

Cat Whisperer · « **Reply #21 on:** January 07, 2011, 01:00:42 PM »

My question is, after one finds the DBTT for a given steel, what difference it makes (in some measurable fassion as with the Charpy notch test. It MAY make relative little difference for SOME materials - until it gets right-much cold.

GGaskill · « **Reply #22 on:** January 07, 2011, 01:53:51 PM »

If the DBTT of 1018 is 41° F as stated in a couple of documents and IF that means there is a significant change in the properties of 1018 at 41° F, then we need to be more considerate of firing 1018 guns in sub-freezing weather. There may not be a gross loss of ductility at 32° F but what about 5° F? It would be best to know what is happening.

Double D · « **Reply #23 on:** January 07, 2011, 02:29:37 PM »

I would think that there would be two other criteria to consider if concern about shooting a cold cannon, how long the cannon has been exposed to the temperature-cold soaked. And how bad you want to go out in the cold and shoot your cannon

dan610324 · « **Reply #24 on:** January 07, 2011, 10:55:17 PM »

yeah correct

I remember that my father told me to not try to bend reinforcement iron for concrete when it was too cold when I was building my garage .
he said that the harder ones could snap instead of bending

0reo · « **Reply #25 on:** January 08, 2011, 01:49:12 AM »

So is 316 good? Or not good?

willdj79 · « **Reply #26 on:** January 08, 2011, 09:50:13 AM »

one of my concerns is that some types of stainless will not blue...

Cat Whisperer · « **Reply #27 on:** January 08, 2011, 11:36:19 AM »

Quote from: 0reo on January 03, 2011, 09:01:10 AM

I'm thinking about a golf ball howitzer.
...

Three things go into safety.

First is the type and state of the material. In steel, I'd use 1018 or 4130/4140. If it is hard it will be more brittle - not good.

Second is the design. Does it have a minimum of the diameter of the powder chamber around and behind it; does it have all the inside corners rounded to minimize stress risers?

Third is the loading. Are the loads kept within the recommended loads (see Switlik - THe More Complete Cannoneer, AA recommendations and the N-SSA recommendations.

Stainless? Hmmm. Have to do some reading up on strengths and toughness.

0reo · « **Reply #28 on:** January 08, 2011, 05:20:50 PM »

I intend to post my design for review when I have it completed but before I have it built so that you guys can approve or advise.

The short answer is that regardless of the material I intend to build my first cannon indestructible.

I'm going beyond the recommended thickness around the powder chamber and continuing a thick wall for the entire length of the bore. It will also be machined out of a solid piece of steel so there won't be any breech plug seams or welding imperfections (except around the trunions.) Internal shapes will be rounded of course, and powder charges will generally be pretty low except for maybe one or two proof charges at a range somewhere.

Still... if 316 is a poor choice then I'll start looking at the other options.

GGaskill · « **Reply #29 on:** January 08, 2011, 06:20:29 PM »

Here are a couple of materials properties pages, one for AISI 316 and another for AISI 1020 which is basically the same as 1018 except hot rolled instead of cold rolled.

As you can see, they are similar.