I think that you will need to give us more info. Specifically, you need to tell us what spec this refers to. Based on some of the things I've seen, you're probably looking at a Euronorm. I would start looking at the following two Euronorms: EN:10028 and EN:10163. But that's just a wild guess based on the link that AdamDrover put in his post.
But to make a SWAG, you would probably start with the assumption that Q345E steel has a yield strength in the neighborhood of 345 MPa. Just remember that for lots of grades in the Euronorm numbering system (I use that term loosely, as there is no particular system that allows you to decipher the meaning of a grade across all Euronorms), the material designation is nominal and the strength decreases as plate thickness increases.
Without knowing the Euronorm that this refers to, you really have no way of being sure.
Who are you buying this steel from? Your supplier should be able to tell you all you want to know.
Engineering is not the science behind building. It is the science behind not building.
you got there chinese steel that is NOT listed in euronorm 10025-2. Rough equivalent would be:
not alloyed simple structural steel of 325 MPa yield strength, deoxidized.
Check the parameters & quality level ABSOLUTELY watertight with steelmaker (NOT seller). Check chemical composure if you want to weld this steel.
Regards
