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DNV-OS-B101 Metallic Materials

Ch.2: Technical Provisions

Sec.1: Rolled Steel for Structural Application

B: Normal Strength Steel

Ch.2 Sec.1
B. Normal Strength Steel

Ch.2 Sec.1
B 100   Scope

Ch.2 Sec.1
B 200   Chemical composition

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

Ch.2 Sec.1
B 400   Mechanical properties

Ch.2 Sec.1 B

Table B1 Chemical composition limits 1) and deoxidation practice for normal strength steel
Grade	C 2)	Si	Mn 2)	P	S	Al	Deoxidation practice
NV A	0.213)	0.50	Min. 2.5 ´ C	0.035	0.035	-	For t £ 50 mm: Any method except rimmed steel 4)
							For t > 50 mm: Killed
NV B	0.21	0.35	Min. 0.80 5)	0.035	0.035	-	For t £ 50 mm: Any method except rimmed steel
							For t > 50 mm: Killed
NV D	0.21	0.10-0.35	Min. 0.60	0.035	0.035	-	For t £ 25 mm: Killed
						Min. 0.020 6)	For t > 25 mm: Killed and fine grain treated
NV E	0.18	0.10-0.35	Min. 0.70	0.035	0.035	Min. 0.020 6)	Killed and fine grain treated
Composition in percentage mass by mass maximum unless shown as a range or as a minimum. C + 1/6 Mn shall not exceed 0.40%. Maximum 0.23% for sections. Rimmed steel may be accepted for sections up to 12.5 mm thickness. Minimum 0.60% when the steel is impact tested. Total content. Acid soluble content, if determined instead, shall be minimum 0.015%.

Ch.2 Sec.1 B

Table B2 Requirements for normal strength steel of improved weldability 1)
Grade			NV BW	NV DW	NV EW
Deoxidation			Killed and fine grain treated
	Chemical composition (ladle analysis, maximum weight % unless range stated)
		C	0.12
		Si	0.10 - 0.50
		Mn	0.60 - 1.40
		P	0.020
		S	0.008
		Cu	0.35
		Cr	0.20
		Ni	0.40
		Mb	0.08
		Al (total)2)	0.06
		Nb 3)4)	0.04
		V 3)4)	0.06
		Ti 4)	0.05
		N	0.010
		B 5)	0.0005
		Pcm	0.22
Tensile test
	Tensile strength (N/mm2)		400 - 520
	Yield stress (N/mm2)
		t £ 25 mm 25 mm < t £ 50 mm 50 mm < t £ 75 mm 75 mm < t £ 100 mm	235 minimum 215 minimum 200 minimum 190 minimum
	Elongation, A5 (%)		22 minimum
Impact test, Charpy V-notch
	Test temperature (°C)		0	-20	-40
	Minimum average energy (J)
		Transverse	40
	Minimum single value (J)
		Transverse	28
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 : 0.06% (Nb+V+Ti)max : 0.10% Boron (maximum 30 ppm) may be added subject to agreement.

Ch.2 Sec.1 B

Table B3 Conditions of supply for normal strength steel
Grade	Thickness, t (mm)	Plates	Sections
NV A, NV B	t £ 50	AR, NR, N, TM	AR, NR, N, TM
	50 < t £?150	AR1), NR, N, TM	AR1), NR, N, TM
NV D	t £ 35	AR, NR, N, TM	AR, NR, N, TM
	35 < t £ 150	NR, N, TM	AR1), NR, N, TM
NV E	t £ 150	N, TM	AR1), NR1), N, TM
Products may be supplied in this condition when especially approved.

Ch.2 Sec.1 B

Table B4 Mechanical properties for normal strength steel
Grade	Yield stress ReHminimum (MPa)	Tensile strength Rm (MPa)	Elongation A5minimum (%)	Impact energy, longitudinal minimum (J)
				Temperature (°C)	t £ 50 (mm)	50 < t £ 70 (mm)	70 < t £ 150 (mm)
NV A NV B NV D NV E	235	400-520	22 3)	+20 0 -20 -40	- 27 1)27 27	34 2)34 34 34	41 2)41 41 41
Impact tests are not required for grade B steel with thickness of 25 mm or less. Impact tests for grade A over 50 mm thickness are not required when the material is produced using fine grain practice and supplied in either N or TM conditions. For full thickness flat test pieces with width 25 mm and gauge length 200 mm, the minimum elongation (%) is reduced to the following values:

Ch.2 Sec.1 B

Table B5 Test units for impact testing of normal strength steel
Grade	Thickness, t (mm)	Plates	Sections
NV A	t £ 50	Not required	Not required
	50 < t £ 150	50 tonnes	Not required
NV B	t £ 25	Not required	Not required
	25 < t £ 150	50 tonnes 1) 2)	50 tonnes 2)
NV D	t £ 150	50 tonnes 1) 2)	50 tonnes 2)
NV E	t £ 150	Each piece	25 tonnes 3)
Maximum 25 tonnes for plates over 50 mm in thickness supplied in the normalising rolled (NR) condition. Maximum 25 tonnes for plates and sections supplied in the as rolled (AR) condition. Maximum 15 tonnes for sections supplied in the as rolled (AR) or normalising rolled (NR) condition.