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CCS FH420 (also written CCS F420, CCS/F420, CCS Grade F420 or FH420 steel plate) is a high-strength steel for welded marine and offshore structures certified by the China Classification Society (CCS) to CCS Rules for Materials and Welding (2024), Part 1, Chapter 3, Section 4 (High Strength Steels for Welded Structures). The number 420 is the minimum yield strength in MPa (up to 50 mm), tensile strength is 520–680 MPa, and the letter F sets the Charpy V-notch test temperature of −60°C. It is delivered thermo-mechanically rolled (TM) or quenched and tempered (QT) and corresponds to grade FH420 in IACS UR W16.
Gangsteel, a steel plate exporter, supplies CCS FH420 plate with CCS class certificates; the requirements below are taken directly from the current CCS rules.
Related CCS grades: CCS AH420 steel plate, CCS DH420 steel plate, CCS EH420 steel plate, CCS FH460 steel plate.
| Element | Heat analysis, TM | Heat analysis, QT |
|---|---|---|
| C | ≤ 0.14 | ≤ 0.18 |
| Mn | 1.00–1.70 | ≤ 1.70 |
| Si | ≤ 0.60 | ≤ 0.80 |
| P | ≤ 0.020 | ≤ 0.020 |
| S | ≤ 0.010 | ≤ 0.010 |
| Al (total) | ≥ 0.02 | ≥ 0.018 |
| Nb | ≤ 0.05 | ≤ 0.06 |
| V | ≤ 0.12 | ≤ 0.12 |
| Ti | ≤ 0.05 | ≤ 0.05 |
| Ni | ≤ 2.00 | ≤ 2.00 |
| Cu | ≤ 0.55 | ≤ 0.50 |
| Cr | ≤ 0.50 | ≤ 1.50 |
| Mo | ≤ 0.50 | ≤ 0.70 |
| N | ≤ 0.025 | ≤ 0.015 |
Source: CCS Rules for Materials and Welding (2024), Part 1, Chapter 3, Table 3.4.3.2 (same values as IACS UR W16 Rev.3). Notes: Nb+V+Ti ≤ 0.26% and Mo+Cr ≤ 0.65% (not applicable to QT); total Al/N ≥ 2:1 unless other nitrogen-binding elements are used; Ni above 2.00% may be approved by CCS; boron, if added, ≤ 0.005%. CCS specifies the chemical composition as a heat (ladle) analysis only; the Rules give no product (check) analysis tolerances for these plates, so no product-analysis column is shown. If a product analysis is required, agree the tolerances in the order.
| Thickness (mm) | Yield ReH min (MPa) | Tensile Rm (MPa) |
|---|---|---|
| 3 ≤ t ≤ 50 | 420 | 520–680 |
| 50 < t ≤ 100 | 390 | 520–680 |
| 100 < t ≤ 250 | 365 | 470–650 |
| Elongation A5 min, T (%) | Elongation A5 min, L (%) | Charpy test temp. | KV avg min, T (J) | KV avg min, L (J) |
|---|---|---|---|---|
| 19 | 21 | −60°C | 28 | 42 |
Source: CCS Rules for Materials and Welding (2024), Part 1, Chapter 3, Table 3.4.7.4. Plates over 600 mm wide are impact tested transversely (T value applies). For N/NR and TM plates one impact test is taken from each piece; for QT plates from each individually heat-treated piece. Above 50 mm, impact specimens are taken at t/4 and t/2.
| Delivery condition | Ceq t ≤ 50 mm | Ceq 50 < t ≤ 100 mm | Ceq 100 < t ≤ 250 mm | CET | Pcm |
|---|---|---|---|---|---|
| TM | 0.43 | 0.45 | 0.47 | n/a | n/a |
| QT | 0.45 | 0.47 | 0.49 | n/a | n/a |
Table 3.4.3.4. Ceq = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15; CET = C + (Mn + Mo)/10 + (Cr + Cu)/20 + Ni/40 (H460 and above, at the mill’s option); Pcm may be used for TM and QT steels with C ≤ 0.12%. n/a = not applicable.
| Delivery condition | Max plate thickness (mm) |
|---|---|
| TM | 150 |
| QT | 150 |
Table 3.4.6.2. Thicker plates (N over 250 mm, QT over 150 mm) need special consideration by CCS. Yield and tensile requirements fall in steps above 50 mm and 100 mm, as shown in the table above.
| Standard / society | Equivalent grade |
|---|---|
| IACS UR W16 | FH420 |
| ABS | AB/FQ43 |
| DNV | VL F420 |
| LR | LR FH42 |
| ASTM A131 | no equivalent (A131 stops at the 40 strength level) |
The IACS member societies use the same unified requirements, so these grades match in chemistry and properties. A plate still needs the certificate of the vessel’s own class society; one plate can carry dual or multiple class certification only when each society’s surveyor witnesses the tests.
Yes. CCS lists the grade as FH420; F420 is a common shorthand for the same steel.
Minimum 420 MPa up to 50 mm, 390 MPa for 50–100 mm and 365 MPa for 100–250 mm. Tensile strength is 520–680 MPa (up to 100 mm).
−60°C, with a minimum average of 28 J transverse or 42 J longitudinal.
FH420 in IACS UR W16, ABS AB/FQ43, DNV VL F420 and LR FH42. ASTM A131 has no grade at this strength.
TM (including TM with accelerated cooling or direct quenching and tempering) or QT. The chemistry and carbon-equivalent limits depend on the delivery condition.
Up to 150 mm in TM or QT condition; thicker plates need special consideration by CCS.
Ceq maximum for plates up to 50 mm is 0.43% (TM), 0.45% (QT). Higher limits apply to thicker plates.
The strength requirements are identical; only the Charpy test temperature changes (0, −20, −40 or −60°C), and E/F grades have tighter P and S limits.
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Equivalent steel grade of CCS/F420 |
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LR/FH42 |
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If you need more stock steel plates in shipbuilding steel plate, please click warehouse sizes.
Related steel grades: CCS/A420, CCS/D420, CCS/F500, CCS/F620
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General Strength |
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High Strength |
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Extra Strength |
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LR equivalent: LR FH42 steel plate
CCS FH36 hull plate: 355 MPa min yield, 490-630 MPa tensile, Charpy at -60°C, chemistry, CEV and equivalent gr
CCS FH32 hull plate: 315 MPa min yield, 440-570 MPa tensile, Charpy at -60°C, chemistry, CEV and equivalent gr
CCS EH36 hull plate: 355 MPa min yield, 490-630 MPa tensile, Charpy at -40°C, chemistry, CEV and equivalent gr
CCS DH36 hull plate: 355 MPa min yield, 490-630 MPa tensile, Charpy at -20°C, chemistry, CEV and equivalent gr
