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KR F40 steel plate, also written as RF40, R F40, KR Grade F40 or market name FH40, is the higher-strength hull structural steel of Korean Register (KR) Rules for the Classification of Steel Ships (IACS UR W11 higher-strength family) with 390 MPa minimum yield, 510-650 MPa tensile strength and Charpy V-notch toughness at -60°C [-76°F]. In the grade name, "F" is the toughness class, and "40" refers to the strength level (historically about 40 kgf/mm²); KR mill certificates commonly use the R prefix (RF40), while FH40 is the common IACS market name with "H" for higher strength. Gangsteel, a steel plate exporter, supplies KR F40 / RF40 plates cut to size for shipbuilding, offshore platforms and marine structures.
Data source: Per IACS UR W11 (ordinary/higher-strength hull structural steel) as adopted in KR Class hull structural steel rules. Official mill/certificate grade is typically RF40 (R F40); KR F40 and FH40 name the same class on this site. Verify the current KR Class edition before ordering.
| Element | C | Mn | Si | P | S | Al (acid sol.) |
|---|---|---|---|---|---|---|
| KR F40 / RF40, % | 0.18 max | 0.90-1.60 | 0.10-0.50 | 0.035 max | 0.035 max | 0.015 min |
| Element | Nb | V | Ti | Cu | Cr | Ni / Mo |
| KR F40 / RF40, % | 0.02-0.05 | 0.05-0.10 | 0.02 max | 0.35 max | 0.20 max | 0.40 max / 0.08 max |
Per IACS UR W11 / Korean Register (KR) hull structural steel rules (higher-strength grades). Nb, V and Al grain-refining elements may be used singly or in combination; when used in combination the individual minima do not apply. Where acid-soluble Al is not less than 0.015%, the Si minimum does not apply. Carbon equivalent: Ceq = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15 (%).
IACS UR W11 / KR Class rules do not separately tabulate product (check) analysis limits for higher-strength grades. When product analysis is required, the finished plate shall meet the heat limits subject to ASTM A6/A6M Table A permitted variations (same practice as other IACS societies).
| Element | Heat analysis limit | Product analysis (heat ± A6) |
|---|---|---|
| C | 0.18 max | 0.22 max |
| Mn | 0.90-1.60 | 0.81–1.72 |
| Si | 0.10-0.50 | 0.04–0.56 |
| P | 0.035 max | 0.045 max |
| S | 0.035 max | 0.045 max |
| Al (acid sol.) | 0.015 min | no A6 Table A tolerance; product value not tabulated |
| Nb | 0.02-0.05 | 0.010–0.060 |
| V | 0.05-0.10 | 0.040–0.110 |
| Ti | 0.02 max | 0.03 max |
| Cu | 0.35 max | 0.38 max |
| Cr | 0.20 max | 0.24 max |
| Ni | 0.40 max | 0.43 max |
| Mo | 0.08 max | 0.09 max |
Per IACS UR W11 / KR Class hull structural steel rules. Product analysis applies only when specified; for a range, results may not vary both above and below it.
| Grade | Yield strength, min | Tensile strength | Elongation, min |
|---|---|---|---|
| KR F40 (RF40) | 390 MPa [57 ksi] | 510-650 MPa [74-94 ksi] | 20% |
Per IACS UR W11 / KR Class hull structural steel rules. Yield and tensile values apply for the full thickness range covered by the grade (typically up to 100 mm for these ship plates).
| Thickness | Test temperature | Longitudinal, avg min | Transverse, avg min |
|---|---|---|---|
| t≤50 mm | -60°C [-76°F] | 39 J | 26 J |
| 50<t≤70 mm | -60°C [-76°F] | 46 J | 31 J |
| 70<t≤100 mm | -60°C [-76°F] | 55 J | 37 J |
Per IACS UR W11 / KR Class hull structural steel rules. Average of three full-size Charpy V-notch specimens; not more than one value below the average and none below 70% of it. Longitudinal values shown; transverse values apply when required by the rules or purchase order. Thicker plates (above 100 mm) may be supplied by agreement with adjusted impact requirements.
Deoxidation: Killed, fine-grain practice. Delivery condition: F-class (R F40 / FH40) grades are supplied normalized or TMCP (often with Ni alloying for -60°C toughness); as-rolled delivery is not permitted. Optional extras by agreement include ultrasonic testing, Z-direction (Z15/Z25/Z35) through-thickness testing and third-party KR survey.
Higher-strength KR A/D/E/F 32/36/40 plates are commonly supplied from about 6 mm to 100 mm thick (up to 150 mm by agreement). Width 1500-4000 mm and length 6000-18000 mm are typical.
| Society / Standard | Equivalent grade |
|---|---|
| KR (Korean Register) | KR F40 / RF40 (FH40) |
| LR (Lloyd's Register) | LR FH40 steel plate |
| ABS | ABS FH40 steel plate |
| CCS | CCS FH40 steel plate |
| ASTM A131/A131M | ASTM A131 FH40 steel plate |
| GL | GL FH40 steel plate |
| DNV | DNV F40 steel plate |
| BV | BV FH40 steel plate |
| NK | NK F40 steel plate |
| RINA | RINA FH40 steel plate |
IACS member societies harmonize ordinary and higher-strength hull grades under UR W11; dual certification (for example KR + ABS, or KR + ASTM A131) is common when ordered that way.
It is a higher-strength hull structural steel under Korean Register (KR) Rules for the Classification of Steel Ships (IACS UR W11), with 390 MPa minimum yield, 510-650 MPa tensile strength and Charpy toughness at -60°C [-76°F]. The mill certificate grade is typically RF40 (R F40); KR F40 and market name FH40 refer to the same strength/toughness class.
KR is Korean Register. The R prefix on the mill grade (RF40 / R F40) is the KR designation. The letter F is the toughness class (Charpy at -60°C [-76°F]), and 40 is the strength level (historically about 40 kgf/mm², now 390 MPa min yield). FH40 adds "H" for higher strength in common IACS market naming.
Minimum 390 MPa (57 ksi), tensile 510-650 MPa (74-94 ksi), elongation about 20% min.
Charpy V-notch at -60°C [-76°F]. Longitudinal average minima are 39 J up to 50 mm, 46 J for 50-70 mm and 55 J for 70-100 mm.
Same 390 MPa strength class. NK A40 (KA40) at 0°C [32°F]; NK D40 (KD40) at -20°C [-4°F]; NK E40 (KE40) at -40°C [-40°F]; NK F40 (KF40) at -60°C [-76°F]. Delivery condition follows the toughness letter rules.
Same F-class toughness (Charpy at -60°C [-76°F]). KR F40 is strength class 40 (390 MPa min yield); NK F32 is strength class 32 (315 MPa min yield).
Requirements are essentially harmonized under IACS UR W11. ABS FH40, LR FH40, DNV F40, BV FH40 and ASTM A131 FH40 (where listed) are counterparts; dual certification is common when ordered with the required surveys.
Yes. Controlled carbon and Ceq give good weldability; preheat may be required for thick sections depending on Ceq and restraint.
F-class (R F40 / FH40) grades are supplied normalized or TMCP (often with Ni alloying for -60°C toughness); as-rolled delivery is not permitted.
Typical supply is about 6-100 mm thick (up to 150 mm by agreement), 1500-4000 mm wide and 6000-18000 mm long.
KR Grade A steel plate | KR Grade B steel plate | KR Grade D steel plate | KR Grade E steel plate | KR A32 steel plate | KR A36 steel plate | KR A40 steel plate | KR D36 steel plate | KR D40 steel plate | KR E32 steel plate | KR E36 steel plate | KR E40 steel plate | KR F32 steel plate | KR F36 steel plate | KR D63 / RD63 steel plate
KR F40 / RF40 (FH40) corresponds to the same grade under the other IACS member classification societies and ASTM A131: LR FH40 steel plate, ABS FH40 steel plate, CCS FH40 steel plate, ASTM A131 FH40 steel plate, GL FH40 steel plate, DNV F40 steel plate, BV FH40 steel plate, NK F40 steel plate, RINA FH40 steel plate.
Gangsteel is specialized in supplying KR general strength steel plate in R A,KR Grade A,Grade A STEEL.KR Grade
Gangsteelis specialized in supplying KRhigh strength steel plate in R E32,KR E32,E32 STEEL PLATE KR Grade EH32
Gangsteelis specialized in supplying KRhigh strength steel plate in R E36,KR E36,E36 STEEL PLATE KR Grade EH36
Gangsteel is specialized in supplying KR extra strength steel plate in R F70,KR F70,F70 STEEL PLATE
