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DNV-OS-B101 Metallic Materials

Ch.2: Technical Provisions

Sec.1: Rolled Steel for Structural Application

D: Extra High Strength Steel

Ch.2 Sec.1
D. Extra High Strength Steel

Ch.2 Sec.1
D 100   Scope

The steel grades shall be killed and fine grain treated.

Ch.2 Sec.1
D 200   Chemical composition

Ch.2 Sec.1
D 300   Heat treatment, condition of supply

Ch.2 Sec.1
D 400   Mechanical properties

The extent of tensile and impact testing shall be each piece.

Ch.2 Sec.1 D
402   Additional requirements for through thickness properties (Z-ductility) are given in E400 for steel grades of improved weldability and, where specified, for grades of normal weldability.

Ch.2 Sec.1 D

Table D1 Chemical composition limits 1) for extra high strength steel
Grade	C	Si	Mn	P	S	Cr 2)	Mo 2)	Ni 2)	Cu 2)	Al 3) 4)	Nb 4)	V 4)	Ti 4)	N
Grade A of all strength levels	0.21	0.10-0.55	1.70	0.035	0.035	0.20	0.08	0.40	0.35	Min. 0.020	0.02 - 0.05	0.05 - 0.10	0.007 - 0.05	-
Grades D and E of all strength levels	0.20	0.10-0.55	1.70	0.030	0.030	0.20	0.08	0.40	0.35	Min. 0.020	0.02 - 0.05	0.05 - 0.10	0.007 - 0.05	-
Grade F of all strength levels	0.18	0.10-0.55	1.60	0.025	0.025	0.20	0.08	0.80	0.35	Min. 0.020	0.02 - 0.05	0.05 - 0.10	0.007 - 0.05	0.009 5)
Composition in percentage mass by mass maximum unless shown as a range or as a minimum. The limits given do not apply when elements are intentionally added. Total content. Acid soluble content, if determined instead, shall be minimum 0.015%. The steel shall contain Al, Nb, V or Ti, either singly or in any combination. When used singly, the steel shall contain the specified minimum content of the element. When Al and Nb are used in combination, the minimum total Al content shall be 0.015% and the minimum Nb content shall be 0.010%. When Al and V are used in combination, the minimum total Al content shall be 0.015% and the minimum V content shall be 0.030%. The total content of Nb+V+Ti shall not exceed 0.12%. 0.012% if Al is present.

Ch.2 Sec.1 D

Table D2 Requirements for extra high strength steels of improved weldability 1)
Grade			NV DW420 NV EW 20	NV DW460 NV EW460	NV DW500 NV EW500
Deoxidation			Killed and fine grain treated
	Chemical composition (ladle analysis, maximum weight % unless range stated)
		C	0.12
		Si	0.10 - 0.50
		Mn	1.65
		P	0.020
		S	0.008
		Cu	0.50
		Cr	0.25
		Ni	1.00
		Mo	0.25
		Al (total)2)	0.06
		Nb 3)4)	0.04
		V 3)4)	0.08
		Ti 4)	0.05
		N	0.010
		B 5)	0.0005
		Pcm	0.22
Tensile test
	Tensile strength(N/mm2)		530 - 680	570 - 720	610 - 770
	Yield stress (N/mm2)
		t £ 50 mm 50 mm < t £ 75 mm 75 mm < t £ 100 mm	420 400 380	460 440 420	500 480 460
	Elongation, A5 (%)		20	19	18
Impact test, Charpy V-notch
	Test temperature (°C)
		Grade DW Grade EW	-20 -40
	Minimum average energy (J)
		Transverse	60
	Minimum single value (J)
		Transverse	42
Minimum average through thickness ductility Zz (%)			35
When scrap material is being used in steel production, the amount of the following residual elements shall be determined and reported and the levels shall not exceed: 0.03% As, 0.01% Sb, 0.02% Sn, 0.01% Pb, 0.01% Bi and 0.005% Ca. Al:N ³ 2:1 (not applicable for titanium killed steel). (Nb+V)max : 0.09%. (Nb+V+Ti)max : 0.13%. Boron (maximum 30 ppm) may be added subject to agreement.

Ch.2 Sec.1 D

Table D3 Mechanical properties for extra high strength steel
Grade	Yield stress ReHminimum (MPa)		Tensile strength Rm (MPa)			Elongation A5minimum (%)		Impact energy, transverse minimum (J)
								Temperature (°C)			t £ 150 (mm)
NV A420 NV D420 NV E420 NV F420	420		530-680			18 1)		0 -20 -40 -60			28
NV A460 NV D460 NV E460 NV F460	460		570-720			17 1)		0 -20 -40 -60			31
NV A500 NV D500 NV E500 NV F500	500		610-770			16 1)		0 -20 -40 -60			33
NV A550 NV D550 NV E550 NV F550	550		670-830			16 1)		0 -20 -40 -60			37
NV A620 NV D620 NV E620 NV F620	620		720-890			15 1)		0 -20 -40 -60			41
NV A690 NV D690 NV E690 NV F690	690		770-940			14 1)		0 -20 -40 -60			46
For full thickness flat test pieces with width 25 mm and gauge length 200 mm, the minimum elongation (%) is reduced to the following values:
Thickness, mm		t £ 10		10 < t £ 15	15 < t £?20		20 < t £?25		25 < t £ 40	40 < t £ 50		t > 50
Strength level 420		11		13	14		15		16	17		18
Strength level 460		11		12	13		14		15	16		17
Strength levels 500 and 550		10		11	12		13		14	15		16
Strength level 620		9		11	12		12		13	14		15
Strength level 690		9		10	11		11		12	13		14