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Stud bolts/Nuts/Fasteners/

ASTM A320 Gr.B8 Cl.2 Stud Bolts ASTM A194 Gr.8 Screwed-on Two Nuts

click to preview the related pdf file: ASTM A320 A320M-2022Download About ASTM A320/A194M Specification It is known by many of our customers that ASTM A320/A194M covers both inch and metric series carbon alloy steel and stainless steel bolting materials. This includes externally threaded bolts, screws, and studs. The specification is intended for alloy and stainless steel bolting material used in pressure vessels, valves, flanges, and fittings designed for low-temperature service. Bars and wire must be hot-wrought, and the material may undergo further processing by centerless grinding or cold drawing. Austenitic stainless steel, belonging to the 300 series, features austenite—a metallic, non-magnetic allotrope of iron—as its primary phase. These alloys contain chromium and nickel (and sometimes nitrogen and molybdenum). Although they…

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click to preview the related pdf file:

About ASTM A320/A194M Specification

It is known by many of our customers that ASTM A320/A194M covers both inch and metric series carbon alloy steel and stainless steel bolting materials. This includes externally threaded bolts, screws, and studs. The specification is intended for alloy and stainless steel bolting material used in pressure vessels, valves, flanges, and fittings designed for low-temperature service. Bars and wire must be hot-wrought, and the material may undergo further processing by centerless grinding or cold drawing. Austenitic stainless steel, belonging to the 300 series, features austenite—a metallic, non-magnetic allotrope of iron—as its primary phase. These alloys contain chromium and nickel (and sometimes nitrogen and molybdenum). Although they cannot be through-hardened, they can undergo carbide solution treatment or both carbide solution treatment and strain-hardening (the latter being classified as “Class 2”).

Charpy Testing and Specifications for ASTM A320 Fasteners in Low-Temperature Environments

ASTM A320 was specifically designed for exceptional performance in low-temperature environments. These fasteners are typically utilized in valves, flanges, fittings, and pressure vessels. According to ASTM A320 specifications, a minimum Charpy impact value is recommended for all grades, with a few exceptions listed below. The Charpy impact test, also known as the pendulum fracture test, measures the total energy absorbed by a material during fracture, providing an indication of the material’s notch toughness. This test, developed by S. B. Russell and Georges Charpy at the turn of the 20th century, remains a critical method for testing high-grade fasteners and other products.

All materials specified under A320/A320M are required to undergo Charpy testing. The only exceptions where impact tests are not necessary include:

  • Carbide solution-treated or strain-hardened grades B8, B8F, B8P, B8M, B8T, and B8LN above -325°F.
  • Carbide solution-treated grades B8, B8P, B9C, and B9LN above -425°F.
  • Ferritic and austenitic steel grades of bolting with a diameter of 1/2″ and smaller.

The heat treatment conditions for the austenitic stainless steels are as follows:

  • Carbide solution-treated (Class 1).
  • Carbide solution-treated after finishing (Class 1A).
  • Annealed and strain-hardened (Class 2).

All austenitic stainless steels must receive a carbide solution treatment, applicable to each class. For Class 2 materials, this involves heating to ambient temperature, maintaining the temperature to allow chromium carbide to dissolve, and then cooling at a rate adequate to prevent carbide precipitation.

ASTM A320 B8F, B8FA, B8M, B8MA

IDENTIFICATIONB8F, B8FA   B8M, B8MA 
GradeWith Added Sulfur (Type 303)With Added Selenium (Type 303 Se)With Added Sulfur (Type 303)
ElementRangeTolerance +/-RangeTolerance +/-RangeTolerance +/-
Carbon, max0.150.01 over0.150.01 over0.080.01 over
Manganese, max2.000.04 over2.000.04 over2.000.04 over
Phosphorus, max0.200.010 over0.200.010 over0.0450.010 over
Sulfur0.15, min.0200.06, max0.010 over0.030, max0.005 over
Silicon, max1.000.05 over1.000.05 over1.000.05 over
Nickel8.0-10.00.108.0-10.00.1010.0-14.00.15
Chromium17.0-19.00.2017.0-19.00.2016.0-18.00.20
Molybdenum2.00-3.000.10
Selenium0.15-0.35
Titanium

ASTM A320 TENSILE STRENGTH AND HARDNESS CHART

GRADE AND CLASSDIAMETERHEAT TREATMENTTENSILE STRENGTH MIN KSIYIELD STRENGTH 0.2% OFFSET KSIELONGATION IN 2IN. MIN, %REDUCTION OF AREA MIN, %HARDNESS MAX
FERRITIC STEELS
L7, L7A, L7B, L7C, L70, L71, L72, L732-1/2″ and underquench and tempered1251051650
L434″ and underquench and tempered1251051650
L7M2-1/2″ and underquench and tempered @ 1150F, min100801850235 HB / 99HRB
L11″ and underquench and tempered1251051650
AUSTENTIC STEELS
CLASS 1: B8, B8C, B8M, B8P, B8F, B8T, B8LN, B8MLNALLcarbide solution treated75303050223 HB or 96 HRB
CLASS 1A: B8A, B8CA, B8MA, B8PA, B8FA, B8TA, B8LNA, B8MLNAALLcarbide solution treated75303050192 HB or 90 HRB
CLASS 2: B8, B8C, B8P, B8F, B8T3/4″ and undercarbide solution treated and strain hardened1251001235321 HB or 35 HRC
over 3/4 to 1″ incl115801530321 HB or 35 HRC
over 1″ to 1-1/4″ incl105652035321 HB or 35 HRC
over 1-1/4″ to 1-1/2″ incl100502845321 HB or 35 HRC
CLASS 2: B8M3/4″ and undercarbide solution treated and strain hardened110951545321 HB or 35 HRC
over 3/4 to 1″ incl100802045321 HB or 35 HRC
over 1″ to 1-1/4″ incl95652545321 HB or 35 HRC
over 1-1/4″ to 1-1/2″ incl90503045321 HB or 35 HRC

ASTM A320 NUT & WASHER COMPATABILITY CHART

GRADENUTSWASHERS
L7A194 Grade 4 or 7F-436
L43A194 Grade 4 or 7F-436
B8 Class 1A194 Grade 8304-SS
B8M Class 1A194 Grade 8M316-SS
B8 Class 2A194 Grade 8304-SS
B8M Class 2A194 Grade 8M316-SS

Why C&N Bolt ASTM A320 Grade B8M Stud Bolts?

We stock a large amount of ASTM A320 ASTM A320 Grade B8M Stud Bolts. Call or email us C&N Huitong and Supply today, where our fastener experts can meet all of your fastener needs… Any fasteners / any material.

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