HY-100 Steel
HY-100 (High Yield 100) is the higher-strength companion grade to HY-80, providing 100,000 psi minimum yield strength for submarine pressure hulls rated for greater operating depths. Its Ni-Cr-Mo-V composition is similar to HY-80 but with adjusted chemistry to achieve the higher yield while maintaining the required subzero fracture toughness. The same MIL-S-16216 specification that governs HY-80 also covers HY-100, with separate chemistry, mechanical property, and toughness requirements for each grade.
HY-100 is used in US Navy submarine pressure hulls where greater depth capability is required than HY-80 can support. Welding requires controlled preheat (typically 200–400°F), low-hydrogen electrodes, and strict inter-pass temperature limits to prevent heat-affected zone hydrogen cracking in the higher-strength material.
Product Forms & Size Range of HY-100 Steel
HY-100 plate per MIL-S-16216 is available in thicknesses from 0.188″ to 5.000″ and widths up to 144″, quenched and tempered. Minimum yield 100,000 psi (690 MPa), minimum tensile 115,000 psi (793 MPa). Charpy V-notch: ≥80 ft·lb at −60°F. Preheat 200–400°F required for welding depending on section thickness.
HEAT TREATMENT OF HY-100 STEEL
HY-100 is produced in the quenched and tempered condition: austenitize at 1600–1700°F, quench in water or polymer, temper at 1050–1150°F (566–621°C) to achieve 100 ksi minimum yield with adequate toughness. The higher yield requires a lower tempering temperature than HY-80. Post-weld stress relief (PWSR) is strongly recommended for complete joint penetration welds in thick sections to minimize residual stress and ensure satisfactory toughness in the heat-affected zone.
HY-80 Steel
Lower-strength companion grade at 80 ksi yield — used for shallower-depth submarine hulls and surface naval structures with guaranteed subzero toughness.
HSLA-100 Steel
Age-hardening weldable alternative to HY-100 — 100 ksi yield without mandatory preheat, used in surface combatant structures.
MIL-S-16216 Specification
The governing MIL specification for both HY-80 and HY-100 quenched-and-tempered naval alloy steel plate.
Certified Material for Critical Service
HY-100 steel is supplied to MIL-S-16216 (same specification as HY-80, with separate Grade B requirements). Mill certifications document full chemistry, yield and tensile strength, elongation, and Charpy impact energy at −60°F. NAVSEA approval is required for all submarine pressure hull material.