CCS DH550 (D550) Steel Plate – Properties & Equivalents

CCS DH550 (also written CCS D550, CCS/D550, CCS Grade D550 or DH550 steel plate) is a high-strength steel for welded marine and offshore structures certified by the China Classification Society (CCS) to CCS Rules for Materials and Welding (2024), Part 1, Chapter 3, Section 4 (High Strength Steels for Welded Structures). The number 550 is the minimum yield strength in MPa (up to 50 mm), tensile strength is 640–820 MPa, and the letter D sets the Charpy V-notch test temperature of −20°C. It is delivered thermo-mechanically rolled (TM) or quenched and tempered (QT) and corresponds to grade DH550 in IACS UR W16.

Gangsteel, a steel plate exporter, supplies CCS DH550 plate with CCS class certificates; the requirements below are taken directly from the current CCS rules.

Related CCS grades: CCS AH550 steel plate, CCS EH550 steel plate, CCS FH550 steel plate, CCS DH500 steel plate, CCS DH620 steel plate.

CCS DH550 chemical composition

CCS DH550 chemical composition, heat (ladle) analysis, % max unless stated, by delivery condition

Element	Heat analysis, TM	Heat analysis, QT
C	≤ 0.16	≤ 0.18
Mn	1.00–1.70	≤ 1.70
Si	≤ 0.60	≤ 0.80
P	≤ 0.025	≤ 0.025
S	≤ 0.015	≤ 0.015
Al (total)	≥ 0.02	≥ 0.018
Nb	≤ 0.05	≤ 0.06
V	≤ 0.12	≤ 0.12
Ti	≤ 0.05	≤ 0.05
Ni	≤ 2.00	≤ 2.00
Cu	≤ 0.55	≤ 0.50
Cr	≤ 0.50	≤ 1.50
Mo	≤ 0.50	≤ 0.70
N	≤ 0.025	≤ 0.015

 

Source: CCS Rules for Materials and Welding (2024), Part 1, Chapter 3, Table 3.4.3.2 (same values as IACS UR W16 Rev.3). Notes: Nb+V+Ti ≤ 0.26% and Mo+Cr ≤ 0.65% (not applicable to QT); total Al/N ≥ 2:1 unless other nitrogen-binding elements are used; Ni above 2.00% may be approved by CCS; boron, if added, ≤ 0.005%. CCS specifies the chemical composition as a heat (ladle) analysis only; the Rules give no product (check) analysis tolerances for these plates, so no product-analysis column is shown. If a product analysis is required, agree the tolerances in the order.

CCS DH550 mechanical properties and impact test

CCS DH550 tensile and Charpy V-notch requirements

Thickness (mm)	Yield ReH min (MPa)	Tensile Rm (MPa)
3 ≤ t ≤ 50	550	640–820
50 < t ≤ 100	530	640–820
100 < t ≤ 250	490	590–770

CCS DH550 elongation and impact energy

Elongation A5 min, T (%)	Elongation A5 min, L (%)	Charpy test temp.	KV avg min, T (J)	KV avg min, L (J)
16	18	−20°C	37	55

Source: CCS Rules for Materials and Welding (2024), Part 1, Chapter 3, Table 3.4.7.4. Plates over 600 mm wide are impact tested transversely (T value applies). For N/NR and TM plates one impact test is taken from each piece; for QT plates from each individually heat-treated piece. Above 50 mm, impact specimens are taken at t/4 and t/2.

CCS DH550 maximum carbon equivalent (plates)

Delivery condition	Ceq t ≤ 50 mm	Ceq 50 < t ≤ 100 mm	Ceq 100 < t ≤ 250 mm	CET	Pcm
TM	0.48	0.50	0.54	0.34	0.25
QT	0.56	0.60	0.64	0.36	0.28

Table 3.4.3.4. Ceq = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15; CET = C + (Mn + Mo)/10 + (Cr + Cu)/20 + Ni/40 (H460 and above, at the mill’s option); Pcm may be used for TM and QT steels with C ≤ 0.12%. n/a = not applicable.

CCS DH550 thickness range and delivery condition

CCS DH550 maximum plate thickness by delivery condition

Delivery condition	Max plate thickness (mm)
TM	150
QT	150

Table 3.4.6.2. Thicker plates (N over 250 mm, QT over 150 mm) need special consideration by CCS. Yield and tensile requirements fall in steps above 50 mm and 100 mm, as shown in the table above.

CCS DH550 equivalent grades

CCS DH550 equivalent grades of other classification societies

Standard / society	Equivalent grade
IACS UR W16	DH550
ABS	AB/DQ56
DNV	VL D550
LR	LR DH55
ASTM A131	no equivalent (A131 stops at the 40 strength level)

The IACS member societies use the same unified requirements, so these grades match in chemistry and properties. A plate still needs the certificate of the vessel’s own class society; one plate can carry dual or multiple class certification only when each society’s surveyor witnesses the tests.

CCS DH550 FAQ

Is CCS D550 the same as CCS DH550?

Yes. CCS lists the grade as DH550; D550 is a common shorthand for the same steel.

What is the yield strength of CCS DH550?

Minimum 550 MPa up to 50 mm, 530 MPa for 50–100 mm and 490 MPa for 100–250 mm. Tensile strength is 640–820 MPa (up to 100 mm).

What is the impact test temperature of CCS DH550?

−20°C, with a minimum average of 37 J transverse or 55 J longitudinal.

What is CCS DH550 equivalent to?

DH550 in IACS UR W16, ABS AB/DQ56, DNV VL D550 and LR DH55. ASTM A131 has no grade at this strength.

How is CCS DH550 supplied?

TM (including TM with accelerated cooling or direct quenching and tempering) or QT. The chemistry and carbon-equivalent limits depend on the delivery condition.

What is the maximum thickness of CCS DH550 plate?

Up to 150 mm in TM or QT condition; thicker plates need special consideration by CCS.

What is the CEV of CCS DH550?

Ceq maximum for plates up to 50 mm is 0.48% (TM), 0.56% (QT). Higher limits apply to thicker plates.

What is the difference between CCS DH550 and the A, D, E and F grades of the same strength?

The strength requirements are identical; only the Charpy test temperature changes (0, −20, −40 or −60°C), and E/F grades have tighter P and S limits.

Equivalent steel grade of CCS/D550
DNV	GL	LR	BV	ABS	NK	KR	RINA
NV D550	GL-D550	LR/D550	BV/D550	ABS/D550	K D550	R D550	RI/D550

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

 

CCS Steel Plate Grade
General Strength	CCS/A	CCS/B	CCS/D	CCS/E
High Strength	CCS/A32	CCS/D32	CCS/E32	CCS/F32
	CCS/A36	CCS/D36	CCS/E36	CCS/F36
	CCS/A40	CCS/D40	CCS/E40	CCS/F40
Extra Strength	CCS/A420	CCS/D420	CCS/E420	CCS/F420
	CCS/A460	CCS/D460	CCS/E460	CCS/F460
	CCS/A500	CCS/D500	CCS/E500	CCS/F500
	CCS/A550	CCS/D550	CCS/E550	CCS/F550
	CCS/A620	CCS/D620	CCS/E620	CCS/F620
	CCS/A690	CCS/D690	CCS/E690	CCS/F690

 

LR equivalent: LR DH55 steel plate