Grade B21

ASTM A540 / A540M Grade B21 Alloy Steel Heavy Hex Bolts, Stud Bolts. ASTM A540 Grade B21 is a high tensile alloy steel bolting grade intended for special application such as nuclear power plant installations. Grade B21 Bolts are available in 5 different tensile class namely 5,4,3,2 &1 depending upon the diameter of the bolts. A540 Grade B21 bolts are manufactured from Chromium Molybdenum Vanadium (Cr-Mo-V) Steel with tensile ranging from 115 ksi to 165 ksi (inch-pound) & 790MPa to 1140 Mpa. These bolts need to undergo charpy v notch impact test as compulsory requirement. Ferrobend can produce these bolting from 1/2 inch through 8 inch with EN 10204 Type 3.1 Certification

ASTM A540 Grade B21 Tensile Class

Grade B21

Class 5

Class 4

Class 3

Class 2

Class 1

ASTM A540 Grade B21 Chemical Composition^A

Element
	Grade B21
	Cr-Mo-V
	Chrome Moly Vanadium
	RangeB, %
Carbon	0.35 - 0.44
Manganese	0.45 - 0.70
PhosphorusC, max	0.025
SulfurC, max	0.025
Silicon	0.15 - 0.35
Chromium	0.80 - 1.15
Nickel	--
Molybdenum	0.50 - 0.65
Vanadium	0.25 - 0.35

^A The intensional addition of Bi, Se, Te and Pb is not permitted.
^B Unless otherwise specified, separate determinations may vary from the specified ranges, except that elements in any heat mush not vary both above and below the specified range.
^C Phosphorus and sulfur content is 0.04% max when open hearth steel is specified.
^D Silicon content is 0.35& mac if vacuum carbon deoxidized.

ASTM A540 Grade B21 Mechanical Properties (Imperial)

Grades	Class	Diameter, inch.	Tensile Strength, min	Yield Strength, 0.2% offset, min	Elongation min, %	Reduction of Area, min, %	Surface Brinell Hardness		Charpy V Notch +10 °F [-12.2 °C]
			Inch Pound Units
			ksi	ksi	In 2 inch.		Min	Max
Grade B21 (Cr-Mo-V)	5	to 2, incl.	120	105	15	50	241	285	D
	5	over 2 to 6, incl.	115	100	15	50	248	302	D
	5	over 6 to 8, incl.	115	100	15	50	255	311	D
	4	to 3, incl.	135	120	13	45	269	331	D
	4	over 3 to 6, incl.	135	120	13	45	277	352	D
	3	to 3, incl.	145	130	12	40	293	352	D
	3	over 3 to 6, incl.	145	130	12	40	308	375	D
	2	to 4, incl.	155	140	11	40	311	401	D
	1	to 4, incl.	165	150	10	35	321	429	D

ASTM A540M Grade B21 Mechanical Properties (Metric)

Grades	Class	Diameter, mm.	Tensile Strength, min	Yield Strength, 0.2% offset, min	Elongation min, %	Reduction of Area, min, %	Surface Brinell Hardness		Charpy V Notch +10 °F [-12.2 °C]
			Metric Units
			Mpa	Mpa	In 50 mm		Min	Max
Grade B21 (Cr-Mo-V)	5	to 50, incl.	825	725	15	50	241	285	D
	5	over 50 to 150, incl.	795	690	15	50	248	302	D
	5	over 150 to 200, incl.	795	690	15	50	255	311	D
	4	to 75, incl.	930	825	13	45	269	331	D
	4	over 75 to 150, incl.	930	825	13	45	277	352	D
	3	to 75, incl.	1000	895	12	40	293	352	D
	3	over 75 to 150, incl.	1000	895	12	40	302	375	D
	2	to 100, incl.	1070	965	11	40	311	401	D
	1	to 100, incl.	1140	1035	10	35	321	429	D

Note A : The minimum average of 3 specimens shall not be less than 35ft-lbf (47 J). One specimen from a set of 3 may be less than 35 ft-lbf (47 J) but not less than 30 ft-lbf (41J).

Note B : The minimum average of 3 specimens shall not be less than 30ft-lbf (41 J). One specimen from a set of 3 may be less than 30 ft-lbf (41 J) but not less than 25 ft-lbf (34J).

Note C : The minimum average of 3 specimens shall not be less than 25ft-lbf (34 J). One specimen from a set of 3 may be less than 25 ft-lbf (34 J) but not less than 20 ft-lbf (27J).

Note D : No minimum values established. Tests shall be run for information only.

ASTM A540 Grade B21 Heat Treatment

Bolting material ordered in the annealed condition shall have a structure suitable for machining. Such annealed material is not intended to be used without subsequent quenching and tempering. Bolting ordered in the liquid quenched and tempered condition shall be uniformly reheated froma temperature below the cooling transformation range to the proper austenitizing temperature, quenched in a liquid medium under substantially uniform conditions, and then uniformly reheated for tempering. The minimum tempering tempereture shall be 850°F [455°C].
Material that has been straintened after quenching and tempering shall be stress relieved by reheating to a temperature not lower than 100°F [55°C] under the tempering temperature.

ASTM A540 Grade B21 Hardness Requirement

The hardness shall be determined on the surface of the material removal of decarburization. The hardness of material in the annealed condition shall not be greater than 235 HB. The hardness of material in the quenched and tempered or quenched, temepred and stress-relieved condition shall be within the limits in hardness column of the mechanical properties table.

ASTM A540 Grade B21 Bolt Marking

Grade	Marking
Grade B21 Class 1	B21-1 BPF
Grade B21 Class 2	B21-2 BPF
Grade B21 Class 3	B21-3 BPF
Grade B21 Class 4	B21-4 BPF
Grade B21 Class 5	B21-5 BPF