DIN Steel classification ST70 (1997) Vs ST70-2 ( 2017) 1

[Tmoose]

I'm looking to break the secret code of older DIN specs.

Some 1997 vintage information claims some fancy bolts were made from St70 steel.

Google so far is incapable of not adding a -2 to that description.

*** Does someone know where to check to confirm how St70 may differ from ST70-2 ?

A 1979 ASM handbook has several StNN specs, and so far they all have a -1, -2 or -3 etc.

After looking at 14 pages, the first 2 digit number after the St designates the UTS. IE, St50 has a UTS = 490 MPA, St 33 UTS =320 MPa .
AND the -1, -2, or -3 does not change that .

My current guess is St70 could have been St70-2 or -3, and would have a UTS of 690 MPa/100kpsi.
And a yield strength around 325 MPA

 

[Dalinus]

According to my old copy of DIN 17100(1980) -1, -2, -3 are so called Gütegruppes (Quality groupes?) and there are differences by type of steelmaking(-1 Thomas process) or desoxidation, chemistry, elongation, CVN requirements.

In DIN 17100 there is only St70-2.

St70-2 should be todays E360 according to EN 10025-2.

 

[Tmoose]

Thank you Dalinus

Dan T