Chemical element composition of Chinese grade ultra-high strength marine steel plate FH460
FH460 Approaching Grade Lookup Table

FH460  Chemical composition

Grade Delivery status Chemical composition (mass fraction)/%
C Si Mn Pᵃ Sᵃ Cu Crᵇ Ni Nbᵇ Vᵇ Tiᵇ Moᵇ N Altᵈ 
FH460 TM ≤0.14 ≤0.60 1.00~1.70 ≤0.020 ≤0.010 ≤0.55 ≤0.50 ≤2.00 ≤0.05 ≤0.12 ≤0.05 ≤0.50 ≤0.025 ≥0.020
ᵃ The P and S content of the structural steel is allowed to be 0.005% higher than the values ​​specified in the table.

ᵇ Except for quenched and tempered steel, Nb+V+Ti ≤ 0.26% and Mo+Cr ≤ 0.65%.

ᶜ With the consent of both the supplier and the buyer, the Ni content may be appropriately increased. 

ᵈ The minimum ratio of total aluminum to nitrogen should be 2:1. When other nitrogen-fixing elements are used, the minimum aluminum content and aluminum-nitrogen ratio are not required.

ᵉ Oxygen content [O] ≤50×10⁶.

ᶠ Oxygen content [O] ≤ 30 × 10⁶. 

ᵍ When boron is intentionally added to enhance the hardenability of steel, the boron content should not exceed 0.005%.

FH460  Mechanical properties

Steel grade Delivery status Tensile tesᵃ ᵇ ᶜ Charpy (V-notch) impact test
Upper yield strength(ReH)/

MPa		 Tensile strength(Rm)/

MPa		 Elongation after fracture(A)/% Test temperature/
℃		 Impact absorption energy(KV₂)/J
Thickness / m m
3～50 >50~100 >100~250 3～100 >100~250 Horizontal Vertical Vertical Horizontal
FH460 N、NR、TM、QT ≥460 ≥430 ≥390 540~720 500~710 ≥17 ≥19 -60  ≥46 ≥31
ᵃ For sheet metal tensile and impact tests, transverse specimens are used; for profiles and bars, longitudinal specimens are used. 

ᵇ When the yield strength is not obvious, the specified plastic elongation strength Rp0.2 can be measured instead of the upper yield strength.

ᶜ If required by the buyer, the yield strength ratio may be no greater than 0.94, subject to negotiation between the supplier and the buyer and specified in the contract.

7.4 Mechanical Properties

7.4.1 The mechanical properties of the steel shall conform to the specifications in the table above. For ultra-high strength grade steels with properties in the thickness direction, the tensile strength in the thickness direction shall not be less than 80% of the specified minimum tensile strength.

7.4.2 When taking impact test specimens for steel with a thickness of 6 mm to <12 mm (or a diameter of 12 mm to <16 mm), small specimens of 5 mm × 10 mm × 55 mm and 7.5 mm × 10 mm × 55 mm can be taken respectively. In this case, the impact absorbed energy will be not less than 2/3 and 5/6 of the specified value, respectively. Larger specimens are preferred.

7.4.3 The impact test results of steel shall be calculated as the arithmetic mean of a set of 3 specimens. One test value is allowed to be lower than the specified value, but it shall not be lower than 70% of the specified value.

7.5 Metallographic Examination

The grain size of ultra-high strength steel should be grade 6 or finer. If the supplier can guarantee this, no inspection is required.

7.6 Surface Quality

7.6.1 The steel surface shall be free from harmful defects such as bubbles, scabs, cracks, folds, inclusions, and pressed-in iron oxide scale. The steel shall not have visually visible delamination.

7.6.2 The steel surface is permitted to have a thin layer of iron oxide scale, rust, and inconspicuous roughness, texture, scratches, and other localized defects caused by pressed-in iron oxide scale and rolling mills, provided these do not impede the inspection of surface quality. However, their depth shall not exceed 0.3 mm, and the minimum permissible thickness of the steel shall be maintained.

7.6.3 Surface defects in the steel may be removed by grinding. The cleaned area shall be smooth and without sharp edges. The thickness reduction shall not exceed 7% of the nominal thickness and not exceed 3 mm, whichever is smaller. The area of ​​a single ground surface shall not exceed 0.25 m², and the sum of the areas of local ground surfaces shall not exceed 2% of the total area. The distance between two ground surfaces shall be greater than their average width; otherwise, they shall be considered as one ground surface. Welding repairs shall comply with the regulations of the China Classification Society. Magnetic particle testing or penetrant testing should be used to confirm that the defects have been completely removed.

7.6.4 For steel strip, since there is no opportunity to remove the defective portion of the surface, a certain degree of surface defect is permissible, but the length of the defective portion of each roll of steel strip should not exceed 6% of the total length of the steel strip.

7.7 Non-destructive testing

7.7.1 Steel plates with through-thickness properties shall be ultrasonically tested according to GB/T 2970 or other standard methods. The test methods and acceptance levels shall be specified in the contract.

7.7.2 Other steel plates may also be subject to non-destructive testing upon the buyer's request, mutual agreement between the supplier and the buyer, and specification in the contract.