ASTM A540/A540M Grade B24 Bolting Specification

Regular and special quality alloy steel bolting materials and bolting components used for nuclear and other special applications

ASTM A540/A540M Grade B24 Hex Bolts, Heavy Hex Bolts, Studs, Socket Head Cap Screws, Threaded Rods

ASTM A540/A540M Grade B24 covers Regular and special quality alloy steel bolting materials and bolting components used for nuclear and other special applications. We offer ASTM A540/A540M Grade B24 Bolting with metric size ranging M6 to M250 & Inch Size range from 1/4 inch to 11 inches. Bolting materials and bolting components supplied to this specification shall conform to the requirements of Specification A962/A962M. These requirements include test methods, finish, thread dimensions, macro etch, marking, certification, optional supplementary requirements, and others. Bolting material shall be supplied hot-rolled or hot-forged or cold-finished at the option of the manufacturer.

ASTM A540/A540M Grade B24 Chemical Requirements

Grade Symbol	UNS Designation	Steel	C	Mn	P, max	S, max	Si	Cr	Ni	Mo	V
ASTM A540/A540M Grade B24	(4340 Mod.)	Cr - Ni - Mo	0.37-0.44	0.70-0.90	0.025 C	0.025 C	0.15-0.35	0.70-0.95	1.65-2.00	0.30-0.40	. . .
ASTM A540/A540M Grade B24	(4340 Mod.)	Product Variation, Over or Under, B %	0.02	0.04	0.01	0.01	0.02	0.05	0.05	0.02	. . .
(A) The intentional 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 must 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 % max if vacuum-carbon deoxidized.

ASTM A540/A540M Grade B24 Mechanical Requirements

Mechanical Requirements (Inch)

Grade	Class	Diameter	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]
Grade	Class	in.	ksi	ksi	In 2 in.	Reduction of Area, min, %	min	max	Charpy V-Notch +10 °F [−12.2 °C]
ASTM A540 Grade B24 (4340 Mod.)	5	to 6, incl	120	105	15	50	248	311	Note 1
		over 6 to 8, incl	115	100	15	50	255	321	Note 1
		over 8 to 9 ¹ / ₂ , incl	115	100	15	50	262	321	Note 1
	4	to 3, incl	135	120	13	45	269	341	Note 1
		over 3 to 6, incl	135	120	13	45	277	352	Note 1
		over 6 to 8, incl	135	120	13	45	285	363	Note 1
		over 8 to 9 ¹ / ₂ , incl	135	120	13	45	293	363	Note 4
	3	to 3, incl	145	130	12	40	293	363	Note 2
		over 3 to 8, incl	145	130	12	40	302	388	Note 2
		over 8 to 9 ¹ / ₂ , incl	145	130	12	40	311	388	Note 4
	2	to 7, incl	155	140	11	40	311	401	Note 2
	2	over 7 to 9 ¹ / ₂ , incl	155	140	11	40	321	415	Note 4
	1	to 6, incl	165	150	10	35	321	415	Note 3
	1	over 6 to 8, incl	165	150	10	35	331	429	Note 4

Mechanical Requirements (Metric)

Grade	Class	Diameter	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]
Grade	Class	mm	MPa	MPa	In 50 mm	Reduction of Area, min, %	min	max	Charpy V-Notch +10 °F [−12.2 °C]
ASTM A540M Grade B24 (4340 Mod.)	5	to 150, incl	825	725	15	50	248	311	Note 1
		over 150 to 200, incl	795	690	15	50	255	321	Note 1
		over 200 to 240, incl	795	690	15	50	262	321	Note 1
	4	to 75, incl	930	825	13	45	269	341	Note 1
		over 75 to 150, incl	930	825	13	45	277	352	Note 1
		over 150 to 200, incl	930	825	13	45	285	363	Note 1
		over 200 to 240, incl	930	825	13	45	293	363	Note 4
	3	to 75, incl	1000	895	12	40	293	363	Note 2
		over 75 to 200, incl	1000	895	12	40	302	388	Note 2
		over 200 to 240, incl	1000	895	12	40	311	388	Note 4
	2	to 180, incl	1070	965	11	40	311	401	Note 2
	2	over 180 to 240, incl	1070	965	11	40	321	415	Note 4
	1	to 150, incl	1140	1035	10	35	321	415	Note 3
	1	over 150 to 200, incl	1140	1035	10	35	331	429	Note 4

ASTM A540/A540M Grade B24 Tolerance

Rolled Bars ^A - Permissible Grinding Depth for Removal of Surface Defects

Diameter, in. [mm]	Minimum Stock Removal Per Side
Diameter, in. [mm]	in.	mm
1 to 1 ¹ / ₈ [25 to 29], incl	0.025	0.64
Over 1 ¹ / ₈ to 1 ¹ / ₄ [29 to 32], incl	0.028	0.71
Over 1 ¹ / ₄ to 1 ³ / ₈ [32 to 35], incl	0.030	0.76
Over 1 ³ / ₈ to 1 ¹ / ₂ [35 to 38], incl	0.033	0.84
Over 1 ¹ / ₂ to 2 [38 to 50], incl	0.042	1.07
Over 2 to 2 ¹ / ₂ [50 to 65], incl	0.052	1.32
Over 2 ¹ / ₂ to 3 ¹ / ₂ [65 to 90], incl	0.072	1.83
Over 3 ¹ / ₂ to 4 ¹ / ₂ [90 to 115], incl	0.090	2.29
Over 4 ¹ / ₂ to 5 ¹ / ₂ [115 to 140], incl	0.110	2.79
Over 5 ¹ / ₂ to 6 ¹ / ₂ [140 to 165], incl	0.125	3.18
Over 6 ¹ / ₂ to 8 ¹ / ₄ [165 to 210], incl	0.155	3.94
Over 8 ¹ / ₄ to 9 ¹ / ₂ [210 to 240], incl	0.203	5.16
(A) Consult the manufacturer on forged bars, cold-finished bars, bored bars, seamless tubes, and forged hollows.

Percent Fibrous Fracture ^ADimension A Width, mm

Dimension B Height, mm	1.5	2.0	2.5	3.0	3.5	4.0	4.5	5.0	5.5	6.0	6.5	7.0	7.5	8.0	8.5	9.0	9.5	10
1.0	98	98	97	96	96	95	94	94	93	93	92	91	91	90	89	89	88	87
1.5	97	96	95	94	93	93	92	91	90	89	88	87	86	85	85	83	82	81
2.0	96	95	94	93	91	90	89	88	86	85	84	82	81	80	79	78	76	75
2.5	95	94	92	91	89	87	86	84	83	81	80	79	76	75	73	72	70	69
3.0	94	93	91	90	87	85	83	81	79	78	76	74	72	70	68	66	64	63
3.5	93	91	89	87	85	83	80	78	75	74	72	69	67	65	63	61	58	56
4.0	93	90	87	85	83	80	78	75	72	70	68	65	62	60	57	55	52	50
4.5	92	89	86	83	80	78	75	72	69	66	63	61	58	55	52	49	46	43
5.0	91	88	84	81	78	75	72	69	66	63	59	56	53	50	48	44	40	38
5.5	90	86	83	79	75	72	69	66	63	59	55	52	48	45	42	38	35	31
6.0	89	85	81	78	74	70	66	63	59	55	51	47	44	40	36	33	29	25
6.5	88	84	80	76	72	68	63	59	55	51	47	43	40	35	31	27	23	19
7.0	87	82	79	74	69	65	61	56	52	47	43	39	34	30	26	21	16	12
7.5	86	81	76	72	67	62	58	53	48	44	40	34	30	25	23	16	11	6
8.0	85	80	75	70	65	70	55	50	45	40	35	30	25	20	15	10	5	0

Rolled Bars ^A- Stock Removal for Magnetic Particle Inspection

Diameter, in. [mm]	Minimum Stock Removal Per Side
Diameter, in. [mm]	in.	mm
1 to 1 ¹ / ₂ [25 to 38], incl	0.075	1.90
Over 1 ¹ / ₂ to 2 [38 to 50], incl	0.090	2.29
Over 2 to 2 ¹ / ₂ [50 to 65], incl	0.125	3.18
Over 2 ¹ / ₂ to 3 ¹ / ₂ [65 to 90], incl	0.156	3.96
Over 3 ¹ / ₂ to 4 ¹ / ₂ [90 to 115], incl	0.187	4.75
Over 4 ¹ / ₂ to 6 [115 to 155], incl	0.250	6.35
Over 6 to 10 [155 to 255], incl	0.312	7.92
(A) Consult the manufacturer on forged bars, cold-finished bars, bored bars, seamless tubes, and forged hollows.

ASTM A540/A540M Grade B24 Bolting Surface Treatment Specifications

Renowned Brands

PTFE MOLYKOTE XYLAN 1014 XYLAN 1424 XYLAN 1070 Ceramic XYLAR 101 XYLAR 2 Dacromet

ASTM A540/A540M Grade B24 Bolting Components Marking

Product Shall be Marked with our manufacturing trade mark "TorqBolt" or "TB" along with the designated Grade.
Grade and manufacturer’s identification symbols shall be applied to one end of studs and to the heads of bolts and screws of all sizes. (If the available area is inadequate, the grade symbol may be marked on one end and the manufacturer’s identification symbol marked on the other end.) For bolts and screws smaller than 1⁄4 in. [6 mm] in diameter and studs smaller than 3⁄8 in. [10 mm] in diameter and for 1⁄4 in. [6 mm] in diameter studs requiring more than a total of three symbols, the marking shall be a matter of agreement between the purchaser and the manufacturer.

ASTM A540/A540M Grade B24 Bolting Certifications

EN 10204 3.1
EN 10204 3.2
PED 2014/68/EC
MERKBLATT AD 2000 W2/W7/W10
API 20 E BSL 1/ BSL 2
NACE MR 0175
NACE MR 0103

ASTM A540/A540M Grade B24 Testing Standards

E18 Test Methods for Rockwell Hardness of Metallic Materials
E21 Test Methods for Elevated Temperature Tension Tests of Metallic Materials
E112 Test Methods for Determining Average Grain Size
E139 Test Methods for Conducting Creep, Creep-Rupture,and Stress-Rupture Tests of Metallic Materials
E150 Recommended Practice for Conducting Creep and Creep-Rupture Tension Tests of Metallic Materials Under Conditions of Rapid Heating and Short Times
E151 Recommended Practice for Tension Tests of Metallic Materials at Elevated Temperatures with Rapid Heating and Conventional or Rapid Strain Rates
E292 Test Methods for Conducting Time-for-Rupture Notch Tension Tests of Materials
E328 Test Methods for Stress Relaxation for Materials and Structures
E566 Practice for Electromagnetic (Eddy Current) Sorting of Ferrous Metals
E709 Guide for Magnetic Particle Testing
F606/F606M Test Methods for Determining the Mechanical Properties of Externally and Internally Threaded Fasteners, Washers, Direct Tension Indicators, and Rivets
F1940 Test Method for Process Control Verification to Prevent Hydrogen Embrittlement in Plated or Coated Fasteners
A962/A962M Specification for Common Requirements for Bolting Intended for Use at Any Temperature from Cryogenic to the Creep Range
A788/A788M for Steel Forgings, General Requirements

ASME Threading Specifications

ASME B1.1 Unified Inch Screw Threads (UN and UNR Thread Form)
ASME B1.3 Screw Thread Gaging System for Dimensional Acceptability - Inch Screw Threads (IN, UNR, and UNJ)
ASME B1.13M Metric Screw Threads - M Profile
ASME B1.21M Metric Screw Threads - MJ Profile
ASME B1.2 Gauges & gauging for Unified Screw Threads(Imperial)

ASTM A540/A540M Grade B24 Supplementary Requirements

S1	Product Analysis
S2	Macroetch Test
S3	Ultrasonic Test
S4	Demonstration of Capability
S5	Fracture Transition Temperature
S6	Magnetic Particle Inspection
S7	Elevated Temperature Test
S8	Alternative Fracture Toughness Requirement

Dimension B Height, mm	1.5	2.0	2.5	3.0	3.5	4.0	4.5	5.0	5.5	6.0	6.5	7.0	7.5	8.0	8.5	9.0	9.5	10
1.0	98	98	97	96	96	95	94	94	93	93	92	91	91	90	89	89	88	87
1.5	97	96	95	94	93	93	92	91	90	89	88	87	86	85	85	83	82	81
2.0	96	95	94	93	91	90	89	88	86	85	84	82	81	80	79	78	76	75
2.5	95	94	92	91	89	87	86	84	83	81	80	79	76	75	73	72	70	69
3.0	94	93	91	90	87	85	83	81	79	78	76	74	72	70	68	66	64	63
3.5	93	91	89	87	85	83	80	78	75	74	72	69	67	65	63	61	58	56
4.0	93	90	87	85	83	80	78	75	72	70	68	65	62	60	57	55	52	50
4.5	92	89	86	83	80	78	75	72	69	66	63	61	58	55	52	49	46	43
5.0	91	88	84	81	78	75	72	69	66	63	59	56	53	50	48	44	40	38
5.5	90	86	83	79	75	72	69	66	63	59	55	52	48	45	42	38	35	31
6.0	89	85	81	78	74	70	66	63	59	55	51	47	44	40	36	33	29	25
6.5	88	84	80	76	72	68	63	59	55	51	47	43	40	35	31	27	23	19
7.0	87	82	79	74	69	65	61	56	52	47	43	39	34	30	26	21	16	12
7.5	86	81	76	72	67	62	58	53	48	44	40	34	30	25	23	16	11	6
8.0	85	80	75	70	65	70	55	50	45	40	35	30	25	20	15	10	5	0

Dimension B Height, mm	1.5	2.0	2.5	3.0	3.5	4.0	4.5	5.0	5.5	6.0	6.5	7.0	7.5	8.0	8.5	9.0	9.5	10
1.0	98	98	97	96	96	95	94	94	93	93	92	91	91	90	89	89	88	87
1.5	97	96	95	94	93	93	92	91	90	89	88	87	86	85	85	83	82	81
2.0	96	95	94	93	91	90	89	88	86	85	84	82	81	80	79	78	76	75
2.5	95	94	92	91	89	87	86	84	83	81	80	79	76	75	73	72	70	69
3.0	94	93	91	90	87	85	83	81	79	78	76	74	72	70	68	66	64	63
3.5	93	91	89	87	85	83	80	78	75	74	72	69	67	65	63	61	58	56
4.0	93	90	87	85	83	80	78	75	72	70	68	65	62	60	57	55	52	50
4.5	92	89	86	83	80	78	75	72	69	66	63	61	58	55	52	49	46	43
5.0	91	88	84	81	78	75	72	69	66	63	59	56	53	50	48	44	40	38
5.5	90	86	83	79	75	72	69	66	63	59	55	52	48	45	42	38	35	31
6.0	89	85	81	78	74	70	66	63	59	55	51	47	44	40	36	33	29	25
6.5	88	84	80	76	72	68	63	59	55	51	47	43	40	35	31	27	23	19
7.0	87	82	79	74	69	65	61	56	52	47	43	39	34	30	26	21	16	12
7.5	86	81	76	72	67	62	58	53	48	44	40	34	30	25	23	16	11	6
8.0	85	80	75	70	65	70	55	50	45	40	35	30	25	20	15	10	5	0