Author Topic: Steel -- characteristics and machining (Read 855 times)

Cat Whisperer · « **on:** April 29, 2005, 04:48:03 PM »

I'd like to open this discussion on some of the characteristics of steel for use in mortars and cannons. Characteristics like the several types of strength, hardness vs. brittleness, hardness and strength, and machineability to mention a few.

We've been playing with 1144 StressProof rounds and DOM tubing of the same material.

We've talked about CRS (cold rolled steel not can't remember ...) 1018 and others.

4130 and 4140 and now 4340 has come into the limelight.

And there is the defintion of 'pre-hardened'.

Where's a good place to start?

CAV Trooper · « **Reply #1 on:** April 29, 2005, 06:02:17 PM »

CW,

Interesting idea for a thread. I'll start it off with a link to a machinability comparison chart I found:

http://www.carbidedepot.com/formulas-machinability.htm

As an aside, I'm going to try to stick with 1144 stressproof for any future projects simply because it has a 100,000psi yield strength "as is" and doesn't need to be heat treated. I like the "more is better" concept when it comes to the strength of gun tubes.

GGaskill · « **Reply #2 on:** April 29, 2005, 07:29:44 PM »

The down side of 1144 is you can't weld it.

CAV Trooper · « **Reply #3 on:** April 30, 2005, 03:44:09 AM »

Quote from: GGaskill

The down side of 1144 is you can't weld it.

Not a problem since I never did learn to weld worth a damn. :wink:

When I finally get around to building a mortar, I'll bolt the trunnion on.

HotGuns · « **Reply #4 on:** April 30, 2005, 08:48:45 AM »

Cat Whisperer...
What would you like to talk about specifically? I've got a bit of a background in metalurgy and have taught some subjects on it . Anything I can help you with ?

Cat Whisperer · « **Reply #5 on:** April 30, 2005, 08:48:54 AM »

Quote from: CAV Trooper

.... I'll start it off with a link to a machinability comparison chart I found:

http://www.carbidedepot.com/formulas-machinability.htm

As an aside, I'm going to try to stick with 1144 stressproof for any future projects simply because it has a 100,000psi yield strength "as is" and doesn't need to be heat treated. I like the "more is better" concept when it comes to the strength of gun tubes.

THANKS! C.T. - I just added it to the REFERENCES sticky. 1144SP is such a dream - the way it cuts and it's strength. Bumped into it a work when raiding the scrap box (with permission).

dominick · « **Reply #6 on:** April 30, 2005, 09:36:09 AM »

I was told by my steel supplier that some DOM tubing begin as a welded tube. Some of the heavier wall tubes are obviously seamless. I was ready to order some 2.5" x .375 wall material for a golf ball size barrel until I found out it was a seamed tube. It was to have a 3.25" x .375 wall trunion sleeve at the breech end. I have since switched to 4130 chrome moly. Any thoughts on that?

GGaskill · « **Reply #7 on:** April 30, 2005, 09:41:42 AM »

4130 should be fine (and it is weldable.) (-:

Cat Whisperer · « **Reply #8 on:** April 30, 2005, 10:12:31 AM »

Quote from: dominick

I was told by my steel supplier that some DOM tubing begin as a welded tube. Some of the heavier wall tubes are obviously seamless. I was ready to order some 2.5" x .375 wall material for a golf ball size barrel until I found out it was a seamed tube. It was to have a 3.25" x .375 wall trunion sleeve at the breech end. I have since switched to 4130 chrome moly. Any thoughts on that?

Agree with George on 4130 being weldable, but make sure you do the required preheat and do it right. 4140 is just beyond that and is tougher to weld right. The issue is cracking and it's a good idea to have a certified or VERY knowledgeable welder do it.

We had a three moulds (for brake pads) made of D2 hardened to Rc60 go bad. Turned out to be a bad batch of steel and the supplier covered the costs - to the tune of several thousand bucks. Cracks showed up in first 10 to fifteen cycles of operation.

Thanks for pointing out the weld before drawing on some DOM. Let me point out that using the steel supplier as a resource is one of the standard industry practices - tap the vendor for all the information you can get.

AND, WELCOME to the forum! Looks like you're starting out on the right foot!

dominick · « **Reply #9 on:** April 30, 2005, 10:42:07 AM »

Thanks for the info Cat Whisperer. Been welding as a profession for 25 years and I'm still learning new and interesting things on the subject.

CAV Trooper · « **Reply #10 on:** April 30, 2005, 12:08:12 PM »

For continuing education purposes, here's a couple of links about steel tubing:

Seamless - http://www.copperweld.com/pdfs/Seamless.pdf

Seamless can be either cold drawn (DOM) or hot finished. The cold finish is best for what we do.

Standard DOM - http://www.copperweld.com/pdfs/DOMBro.pdf

Electric resistance welded before being run through the die and mandrel.

CW is right on the money when he says it pays to talk to your steel supplier before buying stock.