JIS G3128 — High yield point marine steel plates for welded structures
Grades
SHY685N, SHY685NS, SHY785N, SHY785NS
Chemical composition and mechanical properties
| Grade | Chemical composition | Mechanical properties |
|---|---|---|
| SHY685N | C≤0.18, Mn≤1.50, Si≤0.55, P≤0.030, S≤0.030, Cu≤0.50, Ni≤1.00, Cr≤0.80, Mo≤0.40, Nb+V+Ti microalloying, N≤0.012, B≤0.005 | Rm 780-930 MPa, Rp0.2 ≥685 MPa, A≥17%, Akv≥47J at -40℃, quenching and tempering |
| SHY685NS | Lower P/S than SHY685N | Rm 780-930 MPa, Rp0.2 ≥685 MPa, A≥17%, Akv≥47J at -40℃, quenching and tempering |
| SHY785N | C≤0.18, Mn≤1.50, Si≤0.55, P≤0.025, S≤0.020, Cu≤0.50, Ni≤1.50, Cr≤0.80, Mo≤0.60, Nb+V+Ti microalloying, B≤0.005 | Rm 880-1050 MPa, Rp0.2 ≥785 MPa, A≥16%, Akv≥47J at -40℃, quenching and tempering |
Application scope
JIS G3128 specifies high yield strength steel plates for welded structures, belonging to high-strength marine steel grades, including SHY685N, SHY685NS, SHY785N, and SHY785NS, delivered in quenched and tempered condition. The standard provides very high yield strength and excellent low-temperature impact toughness, specifies composition and mechanical requirements, and takes weldability into account, making it suitable for welded load-bearing structures in high-stress marine and offshore engineering applications.
Typical applications
Primarily used in high-stress load-bearing structures and thick plate sections of large container ships, LNG carriers, high-speed vessels, and marine engineering vessels. With its high yield strength, excellent low-temperature toughness, and good weldability, it can significantly reduce cross-section and weight. Suitable for critical structures of large and special vessels and marine engineering equipment with stringent requirements for strength, low-temperature performance, and weld quality.
