ST vs RST

[mTreadwell]

Can anyone tell me the difference between ST and RST designations from DIN 17100? We're supplying replacement parts based on an old drawing from a European manufacturer and this is a new one for me. I'm specifically interested in RST 52-3; I have a crossover chart that shows some RSTs as similar but higher grade than their ST equivalent, but this one isn't listed. Thanks in advance!

 

[Shmulik]

The meaning of 'R' was: Rimmed Steel (= steel containing iron oxide to give a continuous evolution of carbon monoxide while the ingot is solidifying) is NOT permitted.

 

[micalbrch]

Sorry Shmulik, but I think it was just the opposite or I misundertand the meaning of rimmed. R meant killed. S 355 JR2 should now be the equivalent to RSt 52-3.

 

[mTreadwell]

It sounds like you two are saying the same thing (that is, micalbrch misunderstands rimmed as he suggested - or missed the "NOT permitted" at the end of Shmulik's post). Rimmed = CO bubbles allowed to form during cooling. Killed = aluminum or silicon added to capture the oxygen coming out of solution. So despite the non-matching initial, R=killed/not rimmed.

Thanks for the insight guys!