ABS EQ51 Steel Plate – Properties, Chemistry & Equivalents

ABS EQ51 (also written AB/EQ51, ABS Grade EQ51, EQ51 steel plate) is an extra-high-strength steel plate to ABS Rules Part 2, Chapter 1, Section 8 (2018). The number 51 is the yield category (500 MPa minimum, tensile 610-770 MPa) and the prefix EQ sets the Charpy test temperature of -40°C. Grades of this family are supplied quenched and tempered (QT) or thermo-mechanically rolled (TM). It corresponds to grade E500 in IACS UR W16; ASTM A131 does not cover this strength level.

Related grades: ABS AQ51 steel plate ABS DQ51 steel plate ABS FQ51 steel plate ABS EQ47 steel plate.

Gangsteel is specialized in supplying ABS Extra high strength steel plate in ABS Grade EQ51. For more information of Grade EQ51 steel plate, please check them in following:

 

AB/EQ51  Extra high Strength Chemical Composition in Tempering and Quenching

AB/EQ51

ABS EQ51 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	≤ 0.020	≤ 0.030
S	≤ 0.010	≤ 0.020
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/EQ51 Extra high strength property in tempering and quenching

AB/EQ51

ABS EQ51 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/EQ51	500	610-770	16	-40	50	33

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/EQ51
DNV	GL	LR	BV	CCS	NK	KR	RINA
NV E500	GL-E500	LR/EH50	BV/E500	CCS/E500	K E51	R E51	RI/E500

 

 

 

 

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

 

 Relates steel grades: AB/EQ43, AB/EQ47,AB/EQ56,AB/EQ63

 

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 EQ51 thickness and impact requirements

For ABS EQ51 the Charpy V-notch test is run at -40°C with a minimum average of 50 J longitudinal or 33 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 EQ51 equivalent grades

Standard / society	Equivalent grade
ABS	AB/EQ51
IACS UR W16	E500
DNV	VL E500
Other IACS societies (LR, BV, CCS, NK, KR, RINA)	E500 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.