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View Full Version : Why is there 12l14 and 12l15



loose nut
03-02-2015, 10:08 AM
Other than a slight difference in the carbon content that shouldn't really make that much difference why is there two different grades of free machining steel that are so close. Wouldn't one grade do it or is one better then the other for some things.

Rustybolt
03-02-2015, 10:25 AM
One probably heat treats better than the other.

boslab
03-02-2015, 10:26 AM
The carbon may be close but what of the rest, manganese chrome etc etc, there's probably a good reason, but what I don't have a clue, but whatever it is lives in the rest of the analysis
Mark

dian
03-02-2015, 10:29 AM
how does that stuff heat treat?

Rosco-P
03-02-2015, 10:49 AM
http://www.matweb.com/search/DataSheet.aspx?MatGUID=e4a48445c6994e629167c577d73 df5fe

http://www.matweb.com/search/datasheet.aspx?matguid=9e97bc54cb364f4692a42655b94 c5ad7

tmc_31
03-02-2015, 11:31 AM
I just did the MatWeb comparison thing for these two materials. Seems like other that a slight variance in carbon content and iron fe content they are virtually the same. Like Rustybolt, I suspect that one will heat treat better than the other.

One of these days I will get my hands on some so I can try machining it.

Tim

Carm
03-02-2015, 12:25 PM
how does that stuff heat treat?

I am not a metallurgist, but I do play one on TV.
There is insufficient carbon content and lack of other alloy (manganese, here) to assist the carbon into lattice transformation to enable any value from heat treatment in the sense of increasing hardness.
The lead that boosts machinability could be further detriment in that regard and renders unfit for welding.

I'd happily be corrected if wrong.

Rustybolt
03-02-2015, 02:21 PM
how does that stuff heat treat?

If it's anything like 12L14, it case hardens.

Bob Fisher
03-02-2015, 04:04 PM
Agree with Carm, case hardening the only option for a low carbon steel. Bob.

dp
03-02-2015, 05:11 PM
It is a great metal to machine in either form, but I don't think the differences would ever matter in the kinds of things I make. I bought a mixed package of 12L14 from OnlineMetals but when I moved away from Puget Sound I mixed all the raw stock while shipping it and now I don't know my 1018 from my 12L14. I'll have to spark test it all :)

JoeLee
03-02-2015, 05:28 PM
The leaded alloy or free machining steels don't have very good welding characteristics.

JL...................

loose nut
03-02-2015, 07:10 PM
and now I don't know my 1018 from my 12L14. I'll have to spark test it all :)

You'll know when you machine it.

Lee Cordochorea
03-02-2015, 07:26 PM
Rosco P nailed it in post #5. 12L15 has much higher yield strength than 12L14.

tmc_31
03-02-2015, 10:15 PM
Rosco P nailed it in post #5. 12L15 has much higher yield strength than 12L14.

Both 12L14 and 12L15 are available in cold drawn and in hot rolled. Tensile strength is lower in the hot rolled version.

I still don't know why one would pick one over the other unless it is a cost thing.

lakeside53
03-02-2015, 10:16 PM
The leaded alloy or free machining steels don't have very good welding characteristics.

JL...................

Neither does the "12xx"

Optics Curmudgeon
03-02-2015, 11:52 PM
It is a great metal to machine in either form, but I don't think the differences would ever matter in the kinds of things I make. I bought a mixed package of 12L14 from OnlineMetals but when I moved away from Puget Sound I mixed all the raw stock while shipping it and now I don't know my 1018 from my 12L14. I'll have to spark test it all :)

The 12L14 is the rusty one, the stuff has the opposite of corrosion resistance.

wierdscience
03-03-2015, 12:05 AM
I am not a metallurgist, but I do play one on TV.
There is insufficient carbon content and lack of other alloy (manganese, here) to assist the carbon into lattice transformation to enable any value from heat treatment in the sense of increasing hardness.
The lead that boosts machinability could be further detriment in that regard and renders unfit for welding.

I'd happily be corrected if wrong.

Partial credit,your right on the low carbon content and the machinability aspects,but don't rule out weldability in non-critical applications.The 12xx alloys suffer incipient melting along the grain boundary layers where the low melting point of the Lead is achieved before the general melting point of the alloy.So when it's being welded you can see some what looks like grain layer distortion as the weld progresses.

I've welded plenty of it in non-critical applications,mostly using Tig with either 308 or 312 stainless as filler.It does weld nicely once you have the process down.Medium heat and a fast travel rate are good starting points.

It also brazes,hard and soft solders nicely due to the Lead content.

wierdscience
03-03-2015, 12:07 AM
The 12L14 is the rusty one, the stuff has the opposite of corrosion resistance.

Yup,if you've got 12l and 1018 mixed,just spray some with a little water based degreaser.You watch the 12l rust;)

Carm
03-03-2015, 06:59 AM
Partial credit,your right on the low carbon content and the machinability aspects,but don't rule out weldability in non-critical applications. (snip)


Correct, I didn't say it can't be welded. But no designer or engineer would spec that for a fabrication requiring weld mechanicals. Repair, home shop and non-critical are open ended.

huntinguy
03-03-2015, 03:51 PM
Both 12L14 and 12L15 are available in cold drawn and in hot rolled. Tensile strength is lower in the hot rolled version.

I still don't know why one would pick one over the other unless it is a cost thing.

Machining CD material will remove the compression deformation and make it similar to HR. Why pay for what you are going to machine off?