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ASTM A320/A320M

ASTM A320/A320M Bolting Specification

Alloy Steel & Stainless Steel Bolting for Low Temperature Service

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Overview

High-Quality ASTM A320/A320M Bolting Materials by Adfast Component LTD

Adfast Component LTD offers premium alloy, ferritic, and austenitic stainless steel bolting materials compliant with the ASTM A320/A320M specification. Designed for pressure vessels, valves, flanges, and fittings in low-temperature environments, our bolting materials are manufactured using refined ingot cast steel. This mercury-free steel features reduced phosphorous and sulfur levels, meeting stringent impact energy requirements. The materials, including bars and wire rods, undergo hot working, centerless grinding, or cold drawing processes for precision and durability.

Wide Range of Bolting Components for All Applications

Our bolting components include Hex Bolts, Heavy Hex Bolts, Studs, Socket Head Cap Screws, Hex Cap Screws, Threaded Rods, and Threaded Bars, available in imperial sizes from ¼” to 4” and metric sizes from M6 to M100 in fine and coarse threads. Adfast Component LTD also offers bolting components up to 6” with full certification, including PED 2014/68/EC compliance. Certified ASTM/ASME A320/A320M bolting materials are available in stock, ensuring reliable and timely delivery.

Chemical Composition

Grade SymbolDescriptionCMnP,maxS,maxSiNiCrMoB
ASTM A320 L7, L7M, L70Cr – Mo – BRange,%0.38 – 0.48C0.75 – 1.000.0350.040.15 – 0.35…0.80 – 1.100.15 – 0.25…
Product Variation, % Over or Under0.020.040.005 over0.005 over0.02…0.050.02…
ASTM A320 L7A, L71C – Mo (AISI 4037)Range,%0.38 – 0.480.70 – 0.900.0350.040.15 – 0.35……0.20- 0.30…
Product Variation, % Over or Under0.020.030.005 over0.005 over0.02……0.02…
ASTM A320 L7B, L72Cr – Mo (AISI 4137)Range,%0.35 – 0.400.70 – 0.900.0350.040.15 – 0.35…080 – 1100.15 – 0.25…
Product Variation, % Over or Under0.020.030.005 over0.005 over0.02…0.050.02…
ASTM A320 L7C, L73Ni – Cr – Mo (AISI 8740)Range,%0.38 – 0.430.75 – 1.000.0350.040.15 – 0.350.40 – 0.700.40 – 0.600.20- 0.30…
Product Variation, % Over or Under0.020.040.005 over0.005 over0.020.030.030.02…
ASTM A320 L43Ni – Cr – Mo (AISI 4340)Range,%0.38 – 0.430.60 – 0.850.0350.040.15 – 0.351.65 – 2.000.70 – 0.900.20- 0.30…
Product Variation, % Over or Under0.020.030.005 over0.005 over0.020.050.030.02…
ASTM A320 L1Low – C, BRange,%0.17 – 0.240.70 – 1.400.0350.050.15 – 0.30………0.001 – 0.003
Product Variation, % Over or Under0.010.040.005 over0.005 over0.02…………

 

Grade SymbolUNS DesignationC, maxMn, maxP, maxS, maxSi, maxNiCrMoSeTiNNb E  + Ta
ASTM A320 B8, B8AS 30400(304)Range,%0.082.000.0450.0301.008.0-11.018.0 – 20.0……………
Product Variation, % Over or Under0.01 over0.04 over0.010 over0.005 over0.05 over0.150.20……………
ASTM A320 B8C, B8CAS 34700(347)Range,%0.082.000.0450.0301.009.0- 12.017.0- 19.0…………10 × C content, min -1.10 max
Product Variation, % Over or Under0.01 over0.04 over0.010 over0.005 over0.05 over0.150.20…………0.05 under
ASTM A320 B8T, B8TAS 32100(321)Range,%0.082.000.0450.030, max1.009.0- 12.017.0- 19.0……5 × (C+N) min -0.7 max010, max…
Product Variation, % Over or Under0.01 over0.04 over0.010 over0.005 over0.05 over0.150.20……0.05 under1…
ASTM A320 B8P, B8PAS 30500Range,%0.122.000.0450.030, max1.0011- 13.017.0- 19.0……………
Product Variation, % Over or Under0.01 over0.04 over0.010 over0.005 over0.05 over0.150.20……………
ASTM A320 B8F, B8FAS 30300(303)Range,%0.152.000.2000.15, min1.008.0 – 10.017.0- 19.0……………
Product Variation, % Over or Under0.01 over0.04 over0.010 over0.200.05 over0.100.20……………
S 30323(303Se)Range,%0.152.000.200.06, max1.008.0 – 10.017.0- 19.0…00.15- 035………
Product Variation, % Over or Under0.01 over0.04 over0.010 over0.010 over0.05 over0.100.20…0.03 under………
ASTM A320 B8F, B8FAS 30300(303)Range,%0.01 over0.04 over0.010 over0.020.05 over0.10.2. . .. . .. . .……
Product Variation, % Over or Under0.1520.20.06, max18.0-10.017.0-19.0. . .0.15-0.35. . .……
S 30323(303Se)Range,%0.01 over0.04 over0.010 over0.010 over0.05 over0.10.2. . .0.03 under. . .……
Product Variation, % Over or Under0.0820.0450.030, max110.0-14.016.0-18.02.00-3.00. . .. . .……
ASTM A320 B8M, B8MAS 31600(316)Range,%0.082.000.0450.030, max1.0010.0 – 14.016.0 – 18.02.00 – 3.00…………
Product Variation, % Over or Under0.01 over0.04 over0.010 over0.005 over0.05 over0.150.200.10…………
ASTM A320 B8LN, B8LNAS 30453Range,%0.0302.000.0450.0301.008.0-1118.0-20.0………0.10-0.16…
Product Variation, % Over or Under0.005 over0.04 over0.010 over0.005 over0.05 over0.150.20………0.01…
ASTM A320 B8MLN, B8MLNAS 31653Range,%0.0302.000.0450.0301.0010.0-13.016.0-18.02.00-3.00……0.10-0.16…
Product Variation, % Over or Under0.005 over0.04 over0.010 over0.005 over0.05 over0.150.200.10……0.01…
  • (A) The intentional addition of Bi, Se, Te, and Pb is not permitted except for Grade B8F, in which selenium is specified and required.
  • (B) Typical steel compositions used for this grade include 4140, 4142, 4140.10- 4140H, 4142H, and 4145H.
  • (C) For the L7M grade, a minimum carbon content of 0.28 % is permitted provided that the required tensile properties are met in the section sizes involved; the use of AISI 4130 or 4130H is allowed.
  • (D) Class 1 are made from solution-treated material. Class 1A products (B8A, B8CA, B8MA, B8PA, B8FA, and B8TA) are solution-treated in the finished condition. Class 2 products are solution-treated and strain-hardened.
  • (E) Niobium and columbium are interchangeable names for the same element and both names are acceptable for use in A01.22 specifications.

 

Mechanical Requirements

Class and Grade, Diameter, in. [mm]Heat TreatmentMinimum Tempering Temperature, °F [°C]Tensile Strength, min, ksi [MPa]Yield Strength, min, ksi [MPa] (0.2 % offset)Elongation in 2 in. or 50 mm, min, %Reduction of Area, min, %Hardness, max
ASTM A320 L7, L7A, L7B, L7C, L70, L71, L72, L73 21/2 [65] and underAquenched and tempered1100 [593]125[860]105[725]1650321 HBW or 35  HRC
ASTM A320 L43 4[100] and underAquenched and tempered1100 [593]125[860]105[725]1650321 HBW or 35  HRC
ASTM A320 L7M 21/2[65] and underAquenched and tempered1150 [620]100[690]80[550]1850235 HBWBor 99 HRB
ASTM A320 L1 1[25] and underAquenched and tempered. . .125[860]105[725]1650. . .

 

Grade and Class Diameter, in. [mm]Heat TreatmentMinimum Tempering Temperature, °F [°C]Tensile Strength, min, ksi [MPa]Yield Strength, min, ksi [MPa] (0.2 % offset)Elongation in 2 in. or 50 mm, min, %Reduction of Area, min, %Hardness, max
ASTM A320 B8, B8C, B8M, B8P, B8F, B8T, B8LN, B8MLN : Class 1All diameterscarbide solution treated…75 [515]30 [205]3050223 HBWDor  96 HRB
ASTM A320 B8A, B8CA, B8MA, B8PA, B8FA, B8TA, B8LNA, B8MLNA : Class 1AAll diameterscarbide solution treated in the  finished condition…75 [515]30 [205]3050192 HBW or 90  HRB
ASTM A320 B8, B8C, B8P, B8F, B8T : Class 23/4 [20] and under carbide solution treated and strain  hardened…125 [860]100 [690]1235321 HBW or 35  HRC
over 3/4 to 1 [20 to 25], incl…115 [795]80 [550]1530321 HBW or 35  HRC
over 1 to 11/4 [25 to 32], incl…105 [725]65 [450]2035321 HBW or 35  HRC
over 11/4 to 11/2 [32 to 40], inclA…100 [690]50 [345]2845321 HBW or 35  HRC
ASTM A320 B8M : Class 23/4 [20] and undercarbide solution treated and strain  hardened…110 [760]95 [655]1545321 HBW or 35  HRC
over 3/4 to 1 [20 to 25], incl…100 [690]80 [550]2045321 HBW or 35  HRC
over 1 to 11/4 [25 to 32], incl…95 [655]65 [450]2545321 HBW or 35  HRC
over 11/4 to 11/2 [32 to 40], inclA…90 [620]50 [345]3045321 HBW or 35  HRC
  • (A) These upper diameter limits were established on the basis that these were the largest sizes commonly available that consistently met specification property limits. They are not intended as absolute limits beyond which bolting materials could no longer be certified to the specification.
  • (B) To meet the tensile requirements, the Brinell hardness shall not be less than 200 HBW or 93 HRB.
  • (C) Class 1 products are made from solution-treated material. Class 1A products are solution treated in the finished condition for corrosion resistance; heat treatment is critical for enhancing this physical property and meeting the mechanical property requirements. Class 2 products are made from solution-treated material that has been strain hardened. Austenitic steels in the strain-hardened condition may not show uniform properties throughout the cross section, particularly in sizes over 3/4 in. [20 mm] in diameter.
  • (D) For sizes 3/4 in. [20 mm] in diameter and smaller, a maximum hardness of 241 HBW (100 HRB) is permitted.

Impact Test

GradeTest TemperatureCVN Specimen Section Size, mmMin Average Impact Toughness of Three Test Specimens, ft-lbf [J]Min Impact Value of a Single Specimen of Set of Three, ft-lbf [J]
°F°C
ASTM A320 L7M, L70, L71, L72, L73– 100– 7310 × 1020 [27]15 [20]
10 × 7.516 [22]12 [16]
10 × 1020 [27]15 [20]
ASTM A320 L7, L7A, L7B, L7C, L43– 150– 10110 × 7.516 [22]12 [16]
10 × 1040 [54]30 [41]
ASTM A320 L1– 100– 7310 × 7.532 [44]24 [32]

Coating Specifications

A153/A153M Specification for Hot Dip Galvanising (Zinc Coating) on Iron and Steel Hardware
B633 Specification for Electrodeposited Coatings of Zinc on Iron and Steel
B695 Specification for Coatings of Zinc Mechanically Deposited on Iron and Steel
B696 Specification for Coatings of Cadmium Mechanically Deposited
B766 Specification for Electrodeposited Coatings of Cadmium
F1941/F1941M Specification for Electrodeposited Coatings on Mechanical Fasteners, Inch and Metric
F2329/F2329M Specification for Zinc Coating, Hot-Dip, Requirements for Application to Carbon and Alloy Steel Bolts, Screws, Washers, Nuts, and Special Threaded Fasteners

Renowned Brands

Bolting Components Marking

Product Shall be Marked with our manufacturing trade mark Adfast Component LTD 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.

GradeClassGrade Symbol
ASTM A320 Grade B8Class 1 B8
ASTM A320 Grade B8C B8C
ASTM A320 Grade B8M B8M
ASTM A320 Grade B8F B8F
ASTM A320 Grade B8P B8P
ASTM A320 Grade B8T B8T
ASTM A320 Grade B8LN B8F or  B8LN
ASTM A320 Grade B8MLN B8G or  B8MLN
ASTM A320 Grade B8AClass 1A B8A
ASTM A320 Grade B8CA B8TB B or  B8CA
ASTM A320 Grade B8MA B8D or  B8MA
ASTM A320 Grade B8FA B8FA
ASTM A320 Grade B8PA B8H or  B8PA
ASTM A320 Grade B8TA B8J or  B8TA
ASTM A320 Grade B8LNA B8L or  B8LNA
ASTM A320 Grade B8MLNA B8K or  B8MLNA
ASTM A320 Grade B8Class 2 B8SH
ASTM A320 Grade B8C B8CSH
ASTM A320 Grade B8M B8MSH
ASTM A320 Grade B8F B8FSH
ASTM A320 Grade B8P B8PSH
ASTM A320 Grade B8T B8TSH
GradeGrade Symbol
ASTM A320 L1 L1
ASTM A320 L7 L7
ASTM A320 L7A L7A
ASTM A320 L7B L7B
ASTM A320 L7M L7M
ASTM A320 L7C L7C
ASTM A320 L43 L43
ASTM A320 L70 L70
ASTM A320 L71 L71
ASTM A320 L72 L72
ASTM A320 L73 L73

Dimensional Standards

B18.31.2 Imperial Continious Thread, Double End Reduced & Full Body Studs
B18.31.1M Metric Continious Thread, Double End Reduced & Full Body Studs
B16.5 Imperial Full Thread Stud Bolts
B16.5 Metric Full Thread Stud Bolts
B18.2.1 Imperial Square and Hex Bolts and Screws
B18.2.3.1M Metric Hex Cap Screws
B18.2.3.3M Metric Heavy Hex Screws
B18.2.3.5M Metric Hex Bolts
B18.3 Imperial Hexagon Socket and Spline Socket Screws
B18.3.1M Metric Socket Head Cap Screws
B18.6.7M Metric Machine Screws

Certification

  • 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

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

Threading Specs

  • 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)

Supplementary Requirements

S1Impact Properties
S2Lateral Expansion
S3Hardness Testing of Class 2 Bolting Components for ASME Applications
S4Restriction to Use Only Ingot Cast Steel