Well, as always… it depends.
Let’s start with another question – why does steel have such a classification? Why not use one steel type for all structures? The answer is straightforward – money!
Let’s compare prices of steel for typical applications:
S355JR – 100% of the price
S355J0 – 102% of the price
S355J2 – 107% of the price
The widely used EN 10025-2 S355JR is not only the cheapest, it is also available off the shelf in many section shapes. It is fine for most common applications, so it is almost always easy to say: “it is good enough”.
“Almost” is the key word here.
Can steel used in Southern Italy be used just as well in Northern Norway? Usually not, and the reason is the so-called Charpy impact test. It measures the toughness of the material – in other words, how much energy a steel specimen absorbs before it breaks at a given temperature.
In the next post we will expand on this topic and show how to assign steel grades on the basis of Charpy test results. You may find it interesting that in some cases the Eurocode demands a maximum thickness of 40 mm, while other publications allow a plate as thick as 200 mm for the very same case!