ABS AQ70 Steel Plate – Properties, Chemistry & Equivalents

ABS AQ70 (also written AB/AQ70, ABS Grade AQ70, AQ70 steel plate) is an extra-high-strength steel plate to ABS Rules Part 2, Chapter 1, Section 8 (2018). The number 70 is the yield category (690 MPa minimum, tensile 770-940 MPa) and the prefix AQ sets the Charpy test temperature of 0°C. Grades of this family are supplied quenched and tempered (QT) or thermo-mechanically rolled (TM). It corresponds to grade A690 in IACS UR W16; ASTM A131 does not cover this strength level.

Related grades: ABS DQ70 steel plate ABS EQ70 steel plate ABS FQ70 steel plate.

Gangsteel is specialized in supplying ABS Extra high strength steel plate in ABS Grade AQ70. For more information of Grade AQ70 steel plate, please check them in following:

 

 

AB/AQ70  Extra high Strength Chemical Composition in Tempering and Quenching

AB/AQ70

ABS AQ70 chemical composition, % – heat (ladle) analysis and product (check) analysis

Element	Heat analysis (max/min)	Product analysis
C	≤ 0.18	≤ 0.22
Mn	≤ 1.70	≤ 1.84
Si	≤ 0.80	≤ 0.86
P	≤ 0.025	≤ 0.035
S	≤ 0.015	≤ 0.025
Al (total)	≥ 0.018	— (no tolerance in ASTM A6 Table A; product value not given)
Nb	≤ 0.06	≤ 0.07
V	≤ 0.12	≤ 0.14
Ti	≤ 0.05	≤ 0.06
Ni	≤ 3.50	≤ 3.57
Cu	≤ 0.50	≤ 0.53
Cr	≤ 2.00	≤ 2.06
Mo	≤ 0.70	≤ 0.74
N	≤ 0.015	≤ 0.020
Ca	≤ 0.005	— (no tolerance in ASTM A6 Table A; product value not given)
B	≤ 0.005	product analysis not applicable (A6 Table A)

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/AQ70 Extra high strength property in tempering and quenching

AB/AQ70

ABS AQ70 mechanical properties

Grade	Yield ReH min (MPa)	Tensile Rm (MPa)	Elongation A5 min (%)	Charpy test temp (°C)	Impact energy avg min, longitudinal (J)	Impact energy avg min, transverse (J)
AB/AQ70	690	770-940	14	0	69	46

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

Boiler steel plates| Alloy steel plates| High strength plate| Carbon steel plate

 

 

 

 

 

Equivalent steel grade of AB/AQ70
DNV	GL	LR	BV	CCS	NK	KR	RINA
NV A690	GL-A690	LR/AH69	BV/A690	CCS/A690	K A70	R A70	RI/A690

 

 

 

 

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

 

 Related steel grades: AB/DQ70, AB/AQ63, AB/AQ56, AB/AQ51

 

 

ABS Steel Plate Grade Supplier
General Strength	AB/A	AB/B	AB/D	AB/E
High Strength	AB/AH32	AB/DH32	AB/EH32	AB/FH32
	AB/AH36	AB/DH36	AB/EH36	AB/FH36
	AB/AH40	AB/DH40	AB/EH40	AB/FH40
Extra Strength	AB/AQ43	AB/DQ43	AB/EQ43	AB/FQ43
	AB/AQ47	AB/DQ47	AB/EQ47	AB/FQ47
	AB/AQ51	AB/DQ51	AB/EQ51	AB/FQ51
	AB/AQ56	AB/DQ56	AB/EQ56	AB/FQ56
	AB/AQ63	AB/DQ63	AB/EQ63	AB/FQ63
	AB/AQ70	AB/DQ70	AB/EQ70	AB/FQ70

 

 

 

ABS AQ70 thickness and impact requirements

For ABS AQ70 the Charpy V-notch test is run at 0°C with a minimum average of 69 J longitudinal or 46 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.

ABS AQ70 equivalent grades

Standard / society	Equivalent grade
ABS	AB/AQ70
IACS UR W16	A690
DNV	VL A690
Other IACS societies (LR, BV, CCS, NK, KR, RINA)	A690 with the society's own prefix
ASTM A131	no equivalent (A131 stops at 390 MPa)

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.