ASTM A540/A540M Grade B23 Bolting Specification

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

ASTM A540/A540M Grade B23 Hex Bolts, Heavy Hex Bolts, Studs, Socket Head Cap Screws, Threaded Rods

ASTM A540/A540M Grade B23 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 B23 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 B23 Chemical Requirements

Grade Symbol UNS Designation Steel C Mn P, max S, max Si Cr Ni Mo V
ASTM A540/A540M Grade B23 (E-4340-H) Cr - Ni - Mo 0.37-0.44 0.60-0.95 0.025 C 0.025 C 0.15-0.35 0.65-0.95 1.55-2.00 0.20-0.30 . . .
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 B23 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]
in. ksi ksi In 2 in. min max
ASTM A540 Grade B23 (E-4340-H) 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 4
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 9 1 / 2 , incl 135  120  13  45  285 363  Note 4
3 to 3, incl  145  130  12  40 293  363  Note 2 
over 3 to 6, incl  145 130 12 40 302 375 Note 2
over 6 to 9 1 / 2 , incl 145 130 12  40 311 388 Note 4
2 to 3, incl  155 140  11 40 311  388  Note 4
over 3 to 6, incl   155 140 11 40 311 401 Note 4
over 6 to 9 1 / 2 , incl  155 140 11 40 321  415  Note 4
1 to 3, incl  165  150 10  35  321  415  Note 4
over 3 to 6, incl   165 150  10  35 331  429 Note 4
over 6 to 8, incl  165 150 10 35  341 444 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]
mm MPa MPa In 50 mm min max
ASTM A540M Grade B23 (E-4340-H) 5 to 150, incl 825 725 15 50 248 311 Note 1
over 150 to 200 incl 795 690 15 50 255 321 Note 4
over 200 to 240, incl 795 690 15 50 262 321 Note 4
4 to 75, incl 930 825 13 45 269 341 Note 1
over 75 to 150, 930 825 13 45 277 352 Note 1
incl over 150 to 240, incl 930 825 13 45 285 363 Note 4
3 to 75, incl 1000 895 12 40 293 363 Note 2
over 75 to 150, incl 1000 895 12 40 302 375 Note 2
over 150 to 240, incl 1000 895 12 40 311 388 Note 4
2 to 75, incl 1070 965 11 40 311 388 Note 4
over 75 to 150, incl 1070 965 11 40 311 401 Note 4
over 150 to 240, incl 1070 965 11 40 321 415 Note 4
1 to 75, incl 1140 1035 10 35 321 415 Note 4
over 75 to 150, incl 1140 1035 10 35 331 429 Note 4
over 150 to 200, incl 1140 1035 10 35 341 444 Note 4

ASTM A540/A540M Grade B23 Tolerance

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

Diameter, in. [mm] Minimum Stock Removal Per Side
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 A Dimension 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
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 B23 Heat Treatment

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ASTM A540/A540M Grade B23 Bolting Surface Treatment Specifications

ASTM A540/A540M Grade B23 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 B23 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 B23 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 B23 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