What is the difference between properties of Q355NE-Z25 and Q355NE steel plate

Q355NE steel plate is a normalized rolled high-strength low-alloy steel plate with good low temperature impact performance. Q means yield strength; 355 means yield strength value, in MPa; E means grade (passed the -40 degree impact test); when the steel plate is required to have thickness direction properties, add the representative thickness direction (Z direction) to the steel grade. ) performance level symbol, for example: Q355NE-Z15, Q355NE-Z25, Q355NE-Z35.

The chemical composition of Q355NE-Z25 steel plate is the same as that of Q355NE steel plate:
C: not more than 0.18, Si: not more than 0.5, Mn: 0.90-1.65, P: 0.025, S: 0.020, Nb: 0.005-0.05, V: 0.01-0.12, Ti: 0.006-0.05, Cr: not more than 0.30, Ni: not more than 0.50, Cu: not more than 0.40, Mo: not more than 0.10, N: not more than 0.015, Als: not less than 0.01

Tensile yield strength of Q355NE-Z25 steel plate: 470-600
Elongation after fracture of Q355NE-Z25 steel plate: 21%

Z-direction performance of Q355NE-Z25 steel plate: Z-direction performance is the range of tensile force that can be endured in the thickness direction. In the steel structure with welded connection, when the thickness of the steel plate is not less than 40 mm and the tensile force along the thickness direction of the plate is subjected, in order to avoid laminar tearing during welding, it is necessary to use steel that is resistant to laminar tearing. The thick plate has the problem of lamellar tearing, so the Z-direction performance test is proposed, that is, the steel has Z-direction performance.