ABS AQ63 Steel Plate | AQ63 Shipbuilding Steel Plate

ABS AQ63 steel plate, also written as ABS/AQ63, ABS Grade AQ63, American Bureau of Shipping AQ63 or simply AQ63 steel plate, also called ABS EHS AQ63 or AQ63 shipbuilding steel, is an extra-high-strength, fine-grain structural steel of the ABS Rules for Materials and Welding (Part 2, Ch 1, Sec 3, extra high strength steels) with 620 MPa minimum yield (t ≤ 50 mm), 700-890 MPa tensile strength and Charpy V-notch toughness at 0°C [32°F]. In the grade name "A" is the toughness class, "Q" marks the ABS extra-high-strength (quenched and tempered / TMCP) series and "63" is the yield level (63 kgf/mm² class, i.e. 620 N/mm²); the IACS UR W16 designation is AH620. Gangsteel, a steel plate exporter, supplies ABS AQ63 plates in TM or QT condition, cut to size for offshore platforms, jack-up legs and racks, ship structures and other heavy marine steelwork.

Data source: ABS Rules for Materials and Welding, Part 2, Chapter 1, Section 3 (extra high strength steels), which applies the IACS UR W16 requirements; values below are taken from IACS UR W16 Rev.4 Corr.1 (2026) and cross-checked with LR Rules for Materials Ch 3 Section 10 (LR AH62). Verify the current ABS Rules edition and the mill's ABS approval before ordering.

ABS/AQ63 Chemical Composition (Heat Analysis), %

Ladle (heat) analysis per IACS UR W16 Table 1 (as adopted by ABS); all listed elements are to be reported. For TM and N/NR steels Nb+V+Ti ≤ 0.26% and Mo+Cr ≤ 0.65% (not applicable to QT). Total Al to N ratio at least 2:1 unless other nitrogen-binding elements are used. Higher Ni may be approved by ABS. *TM vanadium 0.12% max per IACS UR W16 Rev.4. Grades at this strength level are supplied only TM or QT (no N/NR route). The ABS Rules / IACS UR W16 give heat (ladle) analysis limits only for these grades and no separate product (check) analysis table, so only the heat analysis is shown. Values depend on IACS UR W16 / ABS Rules for Materials and Welding.

ABS AQ63 Carbon Equivalent (Ceq, CET, Pcm), max %

Plates, per IACS UR W16 Table 2 (as adopted by ABS) (IACS splits the last column into 100-150 and 150-250 mm; plate values shown). Ceq = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15; CET = C + (Mn+Mo)/10 + (Cr+Cu)/20 + Ni/40 (H46 and above, at the manufacturer's discretion); Pcm = C + Si/30 + (Mn+Cu+Cr)/20 + Ni/60 + Mo/15 + V/10 + 5B (TM and QT steels with C ≤ 0.12%). N/A means not applicable. Values depend on IACS UR W16 / ABS Rules for Materials and Welding.

ABS/AQ63 Mechanical Properties

Per IACS UR W16 Table 4 (as adopted by ABS) for ABS/AQ63. Elongation on 5.65√S0: 15% min transverse, 17% min longitudinal. Where tensile properties must be maintained through the thickness (e.g. offshore racks), no reduction with thickness is permitted.

ABS AQ63 Elongation on 200 mm Gauge Length (25 mm wide flat specimen)

Transverse full-thickness specimens, per IACS UR W16 Table 5 (as adopted by ABS).

ABS AQ63 Charpy V-Notch Impact Requirements (0°C [32°F])

Per IACS UR W16 Table 4 (as adopted by ABS): average of three full-size specimens; the same energy applies over the whole thickness range. Plates wider than 600 mm are tested transverse; above 50 mm thickness, specimens are taken at t/4 and additionally at t/2.

Delivery Condition and Deoxidation

ABS AQ63 is fully killed and fine-grain treated, made to an ABS-approved manufacturing specification. Permitted delivery conditions: TM or QT (TM includes TM with accelerated cooling and direct quench + tempering). Options by agreement: ultrasonic testing, Z15/Z25/Z35 through-thickness properties (vacuum degassed), and ABS survey with 3.2 certificate stating the specified maximum Ceq, CET or Pcm.

Thickness Coverage

Maximum plate thickness: TM 150 mm, QT 150 mm (IACS UR W16 Table 3); thicker by special consideration. Note that no TM Ceq limit is given above 100 mm, so thicker H62 plates are normally QT. Typical mill sizes are about 8-150 mm thick, 1500-4000 mm wide and 6000-18000 mm long, subject to mill approval.

Equivalent Steel Grades of ABS/AQ63

All IACS members apply UR W16, so chemistry and properties are equivalent, but each plate needs a certificate from the vessel's or structure's own society; dual certification is possible when each surveyor witnesses the tests.

FAQ about ABS AQ63 Steel Plate

What is ABS AQ63 steel plate?

An extra-high-strength fine-grain structural steel to ABS Rules for Materials and Welding Part 2 (IACS UR W16 grade AH620), with 620 MPa minimum yield, 700-890 MPa tensile strength and Charpy testing at 0°C [32°F].

What does AQ63 mean?

A is the toughness class (A 0°C, D -20°C, E -40°C, F -60°C), Q marks the ABS extra-high-strength series and 63 is the yield level in kgf/mm², i.e. 620 N/mm².

What is the yield strength of ABS AQ63?

620 MPa min up to 50 mm, 580 MPa for 50-100 mm and 560 MPa for 100-150 mm. Tensile strength is 700-890 MPa up to 100 mm and 650-830 MPa above.

What are the impact requirements for ABS AQ63?

Charpy V-notch at 0°C [32°F] with an average of at least 41 J transverse or 62 J longitudinal, for all thicknesses.

What is the maximum carbon equivalent for ABS AQ63?

For plate up to 50 mm, Ceq max is 0.50 (TM), 0.56 (QT); limits rise with thickness as tabulated above.

How is ABS AQ63 delivered?

TM or QT, fully killed and fine-grain treated, within the thickness limits of IACS UR W16 and the mill's ABS approval.

What is the difference between ABS AQ63 and ABS DQ63?

Same strength level; ABS AQ63 is impact tested at 0°C [32°F] while ABS DQ63 is tested at -20°C [-4°F].

What is ABS AQ63 equivalent to?

LR AH62, CCS A620, GL A620, DNV A620, BV A620, RINA A620, NK KA63 and KR RA63 (IACS AH620). ASTM A131 has no equivalent at this strength.

Is ABS AQ63 weldable?

Yes, with qualified procedures and ABS-approved consumables of the matching 620 MPa (Y62) strength class; preheat is set from Ceq/CET or Pcm, thickness and restraint.

Other ABS Steel Plate Grades

ABS AH32 steel plate | ABS AH36 steel plate | ABS AH40 steel plate | ABS AQ43 steel plate | ABS AQ47 steel plate | ABS AQ51 steel plate | ABS AQ56 steel plate | ABS AQ70 steel plate | ABS DH32 steel plate | ABS DH36 steel plate | ABS DH40 steel plate | ABS DQ43 steel plate | ABS DQ47 steel plate | ABS DQ51 steel plate | ABS DQ56 steel plate | ABS DQ63 steel plate | ABS DQ70 steel plate | ABS EH32 steel plate | ABS EH36 steel plate | ABS EH40 steel plate | ABS EQ43 steel plate | ABS EQ47 steel plate | ABS EQ51 steel plate | ABS EQ56 steel plate | ABS EQ63 steel plate | ABS EQ70 steel plate | ABS FH32 steel plate | ABS FH36 steel plate | ABS FH40 steel plate | ABS FQ43 steel plate | ABS FQ47 steel plate | ABS FQ51 steel plate | ABS FQ56 steel plate | ABS FQ70 steel plate | ABS Grade A steel plate | ABS Grade B steel plate | ABS Grade D steel plate | ABS Grade E steel plate

Equivalent Class Society Grades

ABS AQ63 corresponds to the same grade under the other IACS member classification societies: LR AH62 steel plate, CCS A620 steel plate, GL A620 steel plate, DNV A620 steel plate, BV A620 steel plate, NK A63 steel plate, KR A63 steel plate, RINA A620 steel plate. ASTM A131 does not cover the 420-690 MPa extra-high-strength levels, so there is no A131 equivalent.