St1100 - german designation - what kind of steel is this?

Werkstoffnummer is 1.8942 for quenched and tempered plates


For thermomechanical rolled sheets I did not find the Werkstoffnummer


Please note that st1100 is not the correct designation. The very old german designation St37, St52, … was related to the minimum tensile strength, not the minimum yield strength. An meanwhile also historic designation related to the minimum yield strength was STE1100. The actual correct designation according EN 10027-1 is S1100 followed by different letters for delivery condition, toughness Level,...
E.g. S1100Q for quenched and tempered steels, S1100MC for thermomechanically rolled steels for cold forming.
Actually there is no EN-standard for plates in S1100.

Thanks for the detailed answer.
I can very well imagine St1100 is not the correct designation (anymore), this is what I've gotten from an equipment manual that is at least 20 yrs old.
It also mentioned UST1120 and UST 960, which is even more unclear to me.

I did not know TM steels existed up to 1100 MPa, this makes it harder for me.

Edit: this is not necessary an S-steel, could be E or something else as it is used in equipment/machinery, not for structural applications. I don't think this matters, however I might as well share this.

The designations with 't' in them (St or UST) were typically referring to UTS values.
If you come across these often by a Stahlschlussel (Key to Steel). It is a great reference.

For one option I find 1.8942 as the WNr., with no ref to DIN or EN. The alloy is called S1100QL (with no reported manufacture).
This alloy is a low C (0.20 max) Ni-Cr-Mo steel. Higher alloy content than any standard ASTM grades that come to my mind.
My hunch is that it has been surface hardened or given some other secondary treatment.

Another is St900/1100 WNr. 1.1381, but I don't find a chemistry for this grade. The values are min Yield and UTS.

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P.E. Metallurgy

Thx for the information, especially this:

The designations with 't' in them (St or UST) were typically referring to UTS values.

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I had never payed attention to this. But now it sure seems logic.

My partner has a key to steel edition on his desk, however he's out of the country... probably for another while.

QL means Quenched+tempered, for low tem. applications (probably 40J @ -60°C or something in those lines. Makes sense for a fine grained steel.


Either way, welding with matching filler means PWHT, right? Even with a Ni-based or Ni-Cr-Fe filler and low cooling rate (Delta T 8/5 around 20 sec.) you cannot avoid PWHT?

At this strength I would think that pre-heat and PWHT are needed.
I would at least try to get an x-ray gun on this stuff and see what the alloy content is.
I would rather use a filler that is very similar in alloy content, just a bit lower in C.
This would help minimize issues later with differences in properties (such as thermal expansion).
And you should try to check to see if it has been surface hardened (carb or nitride).

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P.E. Metallurgy

S1100 is not standardised for plates and therefore only available according data sheets from the different manufacturers, see links above.
Preheating for welding is recommended (depending on thickness), but PWHT is not possible for Q+T-grades as tempering temperature is often as low as 200°C, see the corresponding data sheets.
Another issue can be the yield strength of the welding material, which often does not reach 1100MPa and therefore welds are not located in the highest stressed regions.
S1100 is actually used for telescopic cranes.

Well perhaps the better description is 're-temper'.
I have done 450F for 18 hours to try and get a little bit of SR after welding high strength material (I knew that it had been a 500F original temper).

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P.E. Metallurgy

ulysses, indeed it's for a crane. Manufacturer has informed me by mail that they explicitly forbid repair welding outside of their own workshops, so I'm reluctant to share much information for obvious reasons.
I agree with them though, as there are lots of cowboys out there. On the other hand, they price their spare parts out of this world, which is why I consider a repair, if it can be done correctly.
On the SSAB page you linked to is a very helpful welding guide.

EdStainless, thanks for the helpful advice. I'll report back if we decide to go for a weld repair or not.

king nero said:

It also mentioned UST1120 and UST 960, which is even more unclear to me.

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What bad copies/scans do:
Should have been QST1120 : quenched and self tempered steels...