ABS FQ43 Steel Plate – Properties, Chemistry & Equivalents

ABS FQ43 (also written AB/FQ43, ABS Grade FQ43, FQ43 steel plate) is an extra-high-strength steel plate to ABS Rules Part 2, Chapter 1, Section 8 (2018). The number 43 is the yield category (420 MPa minimum, tensile 530-680 MPa) and the prefix FQ sets the Charpy test temperature of -60°C. Grades of this family are supplied quenched and tempered (QT) or thermo-mechanically rolled (TM), and the 43/47 levels may also be normalized or normalized-rolled. It corresponds to grade F420 in IACS UR W16; ASTM A131 does not cover this strength level.

Related grades: ABS AQ43 steel plate ABS DQ43 steel plate ABS EQ43 steel plate ABS FQ47 steel plate.

 Gangsteel is specialized in supplying ABS Extra high strength steel plate in ABS Grade FQ43. For more information of Grade FQ43 steel plate, please check them in following:

AB/FQ43  Extra high Strength Chemical Composition in Tempering and Quenching

ABS 2022: limits shown are for the quenched and tempered (QT) condition; N/NR/CR and TM supply have different limits in Table 4A. Al/N ≥ 2:1 (not required when other N-binding elements are used); higher C or N may be agreed with ABS; Ni content agreed at qualification; final chemistry must also meet the mill's ABS-approved specification. Product analysis = heat limit ± ASTM A6/A6M Table A permitted variation (band chosen by the specified maximum/upper limit); applies only when product (check) analysis is required; for a range, results may not vary both above and below it. Per ABS Rules for Materials and Welding Part 2 (2022); product analysis tolerances per ABS 2-1-2/5.3 (“chemical tolerances of ASTM A6”) and ASTM A6/A6M 7.2, Table A (also invoked by ASTM A131). Heat limits: ABS 2-1-8/4 Table 4A (2022), QT column.

Crack Sensitivity:  Pcm = (C+Si/30+Mn/20+Cu/20+Ni/60+Cr/20+Mo/15+V/10+5B)%
Carbon Equivalent:  Ceq = 【C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15】%

AB/FQ43 Extra high strength property in tempering and quenching

AB/FQ43

Source: ABS Rules Pt 2, 2-1-8, Table 5A. Either longitudinal or transverse specimens per the order.

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If you need more stock steel plates in shipbuilding steel plate, please click warehouse sizes.

 Related steel grades: AB/FQ47, AB/FQ51, AB/FQ56, AB/FQ63

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ABS FQ43 thickness and impact requirements

For ABS FQ43 the Charpy V-notch test is run at -60°C with a minimum average of 41 J longitudinal or 27 J transverse. The requirement does not change with thickness the way it does for hull grades; the maximum thickness depends on the supply condition and the mill approval (ABS 2-1-8, Table 3). Confirm the thickness limit with the mill approval before ordering.

Grades are equivalent in chemistry and properties because the IACS societies use the same unified requirements. A plate still needs a certificate from the vessel's own classification society, so one plate can carry dual or multiple class certification only when each society's surveyor tests it.