Steel alloys FCMS BMS and MS

I've been reading some "how to" books on making various lathe items and
often they call for FCMS (I believe this is Fast Cutting Mild Steel) and
MS (Mild Steel) and sometimes BMS (Bright Mild Steel) Some of these
terms may be specific to the UK. I'm always trying to get a nice mirror
finish on my projects so I stumbled across 12L14 alloy which was billed
as FCMS. It's a dream to work with but I'm skeptical about how tough it
is cuz it cuts like butter. Anyway, occasionally I'll see books call for
"unleaded" FCMS. The 12L14 Alloy definatlely contains lead. So.....Can
anywone clear this up for me?
Is there another leadless alloy of FCMS that cuts and gives a nice
finish but is tougher due to lack of lead??
Is 1018 alloy basically accepted as MS ("Mild Steel").
Does anyone have a feeling for what US alloy might correspond to BMS?--
how are its properties different from MS?
What are the machining properties of 4130? Perhaps this is the best
compromise between finish and toughness?
TIA
Dan
Reply to
Dan Miller
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At some point in the past somebody told me that British "Mild Steel was the same as "Hot rolled" and "Bright Mild Steel" was the same as "Cold Rold". Makes sense.
John
Reply to
John Hall
4130 is a crome moly steel. Tough to turn; especially when compared to leaded steel. Not exactly cheap to buy either.
I picked up a large bar of steel that appeared to be hot rolled. It machined easily after removing the crusty surface. Sometimes cold rolled (1018) machines well and sometimes it is tought to get a good finish.
chuck
Reply to
Charles A. Sherwood
I buy my steel from JM TULL its a large steel company here in the US and this is the discription of 12l14 in there catalog."Tull-led 12L14 provides superior machining properties,high cutting speeds, and incresed tool life .Surface finish is uniformly smooth and bright . parts close size accuracy the addition of lead has no efect on the mechanicl properities or the internal soundness of the steel." Here are the mechanical properties the catalog gives for cold finished rounds.
1018 tensile psi 64,000 yield 54,000 elongation in 2 inches 15% 12L14 tensile psi 78,000 yield 60,000 elongation in 2 inches 10% 1144 tensile psi 108,000 yield 90,000 elongation in 2 inches 10% 4140 annealed tensile psi 102,000 yield 90,000 elongation in 2 inches18% 4140ht (heat treated rockwell 28 to 32)tensile psi 125,000 yield 105,000 elongation in 2 inches 16%
The 12l14 is not as tough as 1018 but has a higher tensile and yield properities.Agian before anyone flames me these figures came from the manufactures catalog. Here is my thinking 1018 is junk metal its hard to cut and get a good finish I try to avoid using it unless I have to weld it . Most other alloys don't weld very well.
Reply to
tim
12L14 is leaded. Its mechanical properties are quite good, somewhat surprisingly. You can look them up on Google, and you'll find plenty of comparisons.
Don't jump to conclusions about "toughness," just because it contains lead. If you mean what engineers mean by toughness in steel -- impact strength, as measured by notch- or Charpy testers, you shouldn't have much trouble finding that on the Web, either.
There are other free-machining steels, used mostly in high-volume production. They generally contain calcium, phosphorus, and/or sulfur. They're no great deal in the mechanical-properties department, but they're free of lead.
In the US, it's anything from 1008 (sold mostly as sheet for stamping) to 1020.
Not me.
What is your application for the steel?
-- Ed Huntress
Reply to
Ed Huntress
In answer to Ed's question I generally make tools. I get a lot of flack from my wife and friends about using tools to make tools to make tools. (right now I'm making a ball turning tool to make handles for tools) Anyway, they see it as circular...I see it as fun.
Anyway, I want them to look nice as well as be functional and being a relative novice at the lathe (I don't have a milling machine) I spend a lot of time trying to find the right grind for the bits, the right speed etc to get a nce finish. I used to buy all my steel from this steel salvage yard near where I live but then realized that I know little about the alloys I'm picking up. the Shape and size selection is great though. I stumbled across a few pieces that machined really nicely and that got me interested. Now I buy the stuff from a local online place and that way I get the exact size, length, and alloy I want....something to be said for that.As far as steel goes they sell 12L14, 1018, and 4130.
Lots of the stuff I make is threaded, and sometimes I make the nuts etc. I've had little experience with the 12L14, sounds like strength-wise it is fine. I worry about wrenches and stuff chewing it up if I make nuts with it but perhaps this is unfounded as well. Is it noticeably less stiff than 1018? Maybe I'll just stick with it. Is there ever a case where 1018 is preferable?
I'll check out JM Tull as well Charles, thanks for your opinion.
Dan
tim wrote:
Reply to
Dan Miller
In answer to Ed's question I generally make tools. I get a lot of flack from my wife and friends about using tools to make tools to make tools. (right now I'm making a ball turning tool to make handles for tools) Anyway, they see it as circular...I see it as fun.
Anyway, I want them to look nice as well as be functional and being a relative novice at the lathe (I don't have a milling machine) I spend a lot of time trying to find the right grind for the bits, the right speed etc to get a nce finish. I used to buy all my steel from this steel salvage yard near where I live but then realized that I know little about the alloys I'm picking up. the Shape and size selection is great though. I stumbled across a few pieces that machined really nicely and that got me interested. Now I buy the stuff from a local online place and that way I get the exact size, length, and alloy I want....something to be said for that.As far as steel goes they sell 12L14, 1018, and 4130.
Lots of the stuff I make is threaded, and sometimes I make the nuts etc. I've had little experience with the 12L14, sounds like strength-wise it is fine. I worry about wrenches and stuff chewing it up if I make nuts with it but perhaps this is unfounded as well. Is it noticeably less stiff than 1018? Maybe I'll just stick with it. Is there ever a case where 1018 is preferable? ========================
Regarding stiffness, all steel is almost equally stiff. There is a common misconception that stronger steel is stiffer (has a higher modulus of elasticity, or Young's Modulus). 'Tain't so. Stainless is slightly less stiff than carbon steel, but all carbon steels and nearly all alloy steels fall into a range of about +/- 6% on stiffness, regardless of heat treatment or work-hardening.
As for strength, 12L14 has roughly the same strength as other low-carbon steels. Its elongation (a measure of its ductility) is not bad; within the range of other steels of comparable strength. If you want to use it for general-purpose toolmaking and parts-making, check on how it welds, brazes, solders, and case-hardens. I used to know but I forget. The info is readily available.
1018 is fairly easy to machine and it welds very easily, brazes very easily, solders very easily, and it's easy to case-harden. I find that cold-rolled 1018 and 1020 are easier to machine than annealed- or hot-rolled steel in those grades, but I'm not very good at getting good finishes on steel of any grade. Except for 12L14. I've only used it a couple of times but it does machine and finish very nicely.
4130 is a tough, shock-resistant steel of medium strength that has good elongation for its strength, and that welds very well. It's no stiffer than other grades of steel. It was designed originally for aircraft applications, back in the 1920s, and it was specifically alloyed for making safe, reliable welds in a steel with roughly twice the strength of low-carbon steels. It makes very good tubing for airframes. You can weld it with O/A and all electrical methods. It offers no particular advantage for making tools, with rare exceptions. It ain't cheap. You may find occassional use for it in making highly-loaded shafts and other stressed mechanical parts.
Those three steels available from your supplier should meet most of your needs, but I would add one other grade for the home shop: 1070, or something thereabouts. You may need to make something that you can heat-treat into a hard or strong condition, and a plain-carbon steel in the range of 1070 - 1095 is a lot easier to heat-treat with basic equipment than most of the alloy steels are.
-- Ed Huntress
Reply to
Ed Huntress

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