12L14 steel – UK equivalent please..

This topic has 6 replies, 6 voices, and was last updated 25 October 2025 at 12:49 by Clive Foster.

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24 October 2025 at 10:38 #821438
Tim Hooper
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@timhooper66498
Hello all!

I’m making my first foray into engine building, with the BollAero 18 model diesel.

The drawings suggest 12L14 steel for the cylinder.

Having attempted to sort through the minefield of global equivalents for an hour or so, I thought I’d ask the experts here instead!

So…..is there a readily available UK grade, available in short lengths of round bar?

Many thanks

Tim
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24 October 2025 at 10:44 #821440
Michael Gilligan
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@michaelgilligan61133
Some good hints here:

https://songshunsteel.com/product/12l14-sum24l-10718-steel/

MichaelG.
24 October 2025 at 10:50 #821441
Diogenes
Participant
@diogenes
I used leaded mild steel EN1a for the cylinder and cast iron for the piston and contra-piston- it’s a good combo of materials that work well together in this application
24 October 2025 at 11:38 #821448
SillyOldDuffer
Moderator
@sillyoldduffer
Easy answer is EN1A-Pb.

Otherwise, welcome to the bonkers world of steel designations. In the past, individual firms did their own thing, then all the industrial nations standardised without consulting anyone else, then the world went international. A complication is steels are sometimes catalogued by what’s in the alloy, and sometimes by what it’s for.

In the UK, during WW2, the government ordered the British Steel Industry, then several big firms, to produce steel to a common standard. This gave us the Emergency Number Steels, which caught on, and are still used today despite the names being replaced in 1991! No-one makes EN standard steels, so what you get is a substitute. Oh, and the European EN system isn’t related to British EN numbers. It’s a fine mess!

12L14 is a free-cutting mild-steel. The specification is American. The steel is similar to what we know in the UK as EN1aPb. Free-cutting is achieved by adding a dash of either Lead or Sulphur to Carbon mild-steel, and it’s not always clear if “EN1a” is the Lead or Sulphur variety. Potentially confusing because they behave slightly differently. If Lead is important, look for EN1A-Pb.

Other alternatives to the AISI 12L14 include: BS 230M07Pb, DIN 9SMn28Pb, DIN 11SMnPb30, S250PB, 1914, Werkstoff 1.0718 and EN10277-3. There will be Japanese and other equivalents.

For most purposes only the ‘free-cutting’ part matters. Exceptions include a need for more strength, or if the part is to be case-hardened, welded, galvanised or electroplated. If any of these matter, read the specifications.

Dave
24 October 2025 at 11:57 #821451
JasonB
Moderator
@jasonb
Or if you want to come out of the dark ages 230M07pb is the upto date specification that some suppliers may sell the outdated EN1Apb spec as. Ideal for compression ignition and glow engine cylinders. M-machine have a good range and you can be sure what you get is what you ask for.

While you are at it “stressproof” steel specified for the crankshaft is a US trade name so no direct equivelent so either use a good brand HT bolt as suggested or order some EN8 (080M40) for the crankshaft at the same time

6082 T6 would be the right grade for the parts spec’d as “Aluminium bar”. Sometimes still listed as HE30.
25 October 2025 at 10:59 #821580
Tim Hooper
Participant
@timhooper66498
Firstly, many thanks to all of you for taking the time to reply!

I’m glad that I’m not the first to get confused by all of the regional variables and specs of the alloys available. To a relative numpty like me, it can be a bit off-putting.

You’ve all given me some excellent leads to follow.

Thank you again.

Tim
25 October 2025 at 12:49 #821582
Clive Foster
Participant
@clivefoster55965
Jason / Tim

Yeah way too many steel specifications out there for folk like us to get our heads round.My 1990 copy of the ASM metals handbook has over 1,000 slightly bigger than A4 size pages on commercially available steels and ferrous alloys as volume 1, volume 2 is everything else ie non ferrous et al. Lord knows how many specification there are in there. I’m certainly not going to count them! Not a single EN number in sight either.

Final print version of the ASM book ran to 6 book shelf busting volumes. Yikes.

The ME & Home Workshop world really needs a short listing of the useful to us and easy to get modern metals specifications for both steels and other metals. Along with some notes on use and specific properties.

John Bradley does very decent guide to more modern steel specifications in 5 or so A4 pages as part of Volume 2 of his 3 book set The Racing Motorcycle, a technical guide for constructors. The guts of it being a listing of the modern designations of 8 useful steels including a column for similar steels of equivalent properties but different specification. Including EN numbers. Also has some other useful tables such as ruling sections for improving properties by heat treatment, what the heat treatment letters actually mean and comparisons of real world strength showing why the expensive stuff may not actually be better for what you want to do.

It’s been my go to guide ever since I bought the book in 2003. Just enough data for nearly everything I do where I can easily find it.

Would be fine starting point for an article to two. Obviously suitably tweaked and amended to suit our use and suppliers.

Clearly correct material selection for wheel spindles to avoid high stress cracking and breakage is important before charging round the Isle of Man at a hundred and umpety-ump mph. Not so much of an issue when tootling round the local ME track at around fast jog pace.

Clive
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