ASTM A320 Specification
The ASTM A320 specification is another popular specification used in the fastener industry. This specification covers alloy steel bolting materials for pressure vessels, valves, flanges, and fittings for low-temperature service. Each alloy shall conform to the prescribed chemical composition requirements. The material, as represented by the tension specimens, shall conform to the requirements as to tensile properties such as tensile strength, yield strength, elongation, and hardness. The material shall meet the prescribed impact energy absorption requirements and the recommended test temperature. Mechanical tests shall be conducted on the material, namely: impact testing, tension testing, and hardness testing. Several grades are covered, including both ferritic and austenitic steels designated L7, B8, etc. Selection will depend on design, service conditions, mechanical properties, and low-temperature characteristics. ASTM A320 chemical requirements are listed underneath the ASTM A320 mechanical requirements. Many of Lightning Bolt’s items are also duel certified. Email us today to find out how we can help! sales@lightningboltandsupply.com
ASTM A320 TENSILE STRENGTH AND HARDNESS
ASTM A320 TENSILE STRENGTH AND HARDNESS CHART
| Grade and Class | Diameter | Heat Treatment | Tensile Strength Min KSI | Yield Strength 0.2% Offset KSI | Elongation in 2in. Min, % | Reduction of Area Min, % | Hardness max |
|---|---|---|---|---|---|---|---|
| FERRITIC STEELS | |||||||
| L7, L7A, L7B, L7C, L70, L71, L72, L73 | 2-1/2" and under | quench and tempered | 125 | 105 | 16 | 50 | |
| L43 | 4" and under | quench and tempered | 125 | 105 | 16 | 50 | |
| L7M | 2-1/2" and under | quench and tempered @ 1150F, min | 100 | 80 | 18 | 50 | 235 HB / 99HRB |
| L1 | 1" and under | quench and tempered | 125 | 105 | 16 | 50 | |
| AUSTENTIC STEELS | |||||||
| CLASS 1: B8, B8C, B8M, B8P, B8F, B8T, B8LN, B8MLN | ALL | carbide solution treated | 75 | 30 | 30 | 50 | 223 HB or 96 HRB |
| CLASS 1A: B8A, B8CA, B8MA, B8PA, B8FA, B8TA, B8LNA, B8MLNA | ALL | carbide solution treated | 75 | 30 | 30 | 50 | 192 HB or 90 HRB |
| CLASS 2: B8, B8C, B8P, B8F, B8T | 3/4" and under | carbide solution treated and strain hardened | 125 | 100 | 12 | 35 | 321 HB or 35 HRC |
| over 3/4 to 1" incl | 115 | 80 | 15 | 30 | 321 HB or 35 HRC | ||
| over 1" to 1-1/4" incl | 105 | 65 | 20 | 35 | 321 HB or 35 HRC | ||
| over 1-1/4" to 1-1/2" incl | 100 | 50 | 28 | 45 | 321 HB or 35 HRC | ||
| CLASS 2: B8M | 3/4" and under | carbide solution treated and strain hardened | 110 | 95 | 15 | 45 | 321 HB or 35 HRC |
| over 3/4 to 1" incl | 100 | 80 | 20 | 45 | 321 HB or 35 HRC | ||
| over 1" to 1-1/4" incl | 95 | 65 | 25 | 45 | 321 HB or 35 HRC | ||
| over 1-1/4" to 1-1/2" incl | 90 | 50 | 30 | 45 | 321 HB or 35 HRC |
ASTM A320 CHEMICAL REQUIREMENTS
ASTM A320 GRADES L7, L7M, L70, L7A, L7B, L72, L7C, L73, L43, L1
| Identification | L7, L7M, L70 | L7A, L71 | L7B, L72 | L7C, L73 | L43 | L1 | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Grade | Chromium- Molybdenum (AISI 4140, 4142, or 4145) | Carbon- Molybdenum (AISI 4037) | Chromium- Molybdenum (AISI 4137) | Nickel-Chromium-Molybdenum (AISI 8740) | Nickel-Chromium- (AISI 4340) | Low-Carbon Boron | ||||||
Element | Range | Tolerance +/- | Range | Tolerance +/- | Range | Tolerance +/- | Range | Tolerance +/- | Range | Tolerance +/- | Range | Tolerance +/- |
| Carbon | 0.38-0.48 | .002 | 0.35-0.40 | .002 | 0.35-0.40 | .002 | 0.38-0.43 | .002 | 0.38-0.43 | .002 | 0.17-0.24 | .002 |
| Manganese | 0.75-1.00 | 0.04 | 0.70-0.90 | 0.03 | 0.70-0.90 | 0.03 | 0.75-1.00 | 0.004 | 0.60-0.85 | 0.03 | 0.70-1.40 | 0.004 |
| Phosphorus, max | 0.035 | 0.005 over | 0.035 | 0.005 over | 0.035 | 0.005 over | 0.035 | 0.005 over | 0.035 | 0.005 over | 0.035 | 0.005 over |
| Sulfur, max | 0.040 | 0.005 over | 0.040 | 0.005 over | 0.040 | 0.005 over | 0.040 | 0.005 over | 0.040 | 0.005 over | 0.050 | 0.005 over |
| Silicon | 0.15-0.35 | 0.02 | 0.15-0.35 | 0.02 | 0.15-0.35 | 0.02 | 0.15-0.35 | 0.02 | 0.15-0.35 | 0.02 | 0.15-0.30 | 0.02 |
| Nickel | - | - | - | - | - | - | 0.40-0.70 | 0.03 | 1.65-2.00 | 0.05 | - | |
| Chromium | 0.80-1.10 | - | - | - | 0.80-1.10 | 0.05 | 0.40-0.60 | 0.03 | 0.70-0.90 | 0.03 | - | |
| Molybdenum | 0.15-0.25 | 0.20-0.30 | 0.02 | 0.15-0.25 | 0.02 | 0.20-0.30 | 0.02 | 0.20-0.30 | 0.02 | - | ||
| Boron | - | - | - | - | - | - | - | - | - | - | - | - |
ASTM A320 B8, B8A
| Identification | B8, B8A | B8C, B8CA | ||
|---|---|---|---|---|
| Grade | Unstablized 18 Chromium-8 Nickel (AISI Type 304 Stainless) | Stabilized 18 Chromium-8 Nickel (AISI Type 347) | ||
Element | Range | Tolerance +/- | Range | Tolerance +/- |
| Carbon, max | 0.08 | 0.01 over | 0.08 | 0.01 over |
| Manganese, max | 2.00 | 0.04 over | 2.00 | 0.04 over |
| Phosphorus, max | 0.045 | 0.010 over | 0.045 | 0.010 over |
| Sulfur, max | 0.030 | 0.005 over | 0.030 | 0.005 over |
| Silicon | 1.00 | 0.05 over | 1.00 | 0.05 over |
| Nickel | 8.0-10.5 | 0.15 | 9.0-13.0 | 0.15 |
| Chromium | 18.0-20.0 | 0.20 | 17.0-19.0 | 0.20 |
| Columbium + Tantalum | - | - | 10X Carbon, min | 0.05 under |
ASTM A320 B8T, B8TA, B8P, B8PA
| Identification | B8T, B8TA | B8P, B8PA | ||
|---|---|---|---|---|
| Grade | Stabilized 18 Chromium-8 Nickel (AISI 321) | Unstabilized 18-Chromium-8Nickel (AISI Type 305 with restricted Carbon) | ||
Element | Range | Tolerance +/- | Range | Tolerance +/- |
| Carbon, max | 0.08 | 0.01 over | 0.08 | 0.01 over |
| Manganese, max | 2.00 | 0.04 over | 2.00 | 0.04 over |
| Phosphorus, max | 0.045 | 0.010 over | 0.045 | 0.010 over |
| Sulfur | 0.030, max | 0.005 over | 0.030, max | 0.005 over |
| Silicon, max | 1.00 | 0.05 over | 1.00 | 0.05 over |
| Nickel | 9.0-12.0 | 0.15 | 10.5-13.0 | 0.15 |
| Chromium | 17.0-19.0 | 0.20 | 17.0-19.0 | 0.20 |
| Molybdenum | - | - | - | |
| Selenium | - | - | - | |
| Titanium | 5x Carbon, min | 0.05 under | - |
ASTM A320 B8F, B8FA, B8M, B8MA
| Identification | B8F, B8FA | B8M, B8MA | ||||
|---|---|---|---|---|---|---|
| Grade | With Added Sulfur (Type 303) | With Added Selenium (Type 303 Se) | With Added Sulfur (Type 303) | |||
Element | Range | Tolerance +/- | Range | Tolerance +/- | Range | Tolerance +/- |
| Carbon, max | 0.15 | 0.01 over | 0.15 | 0.01 over | 0.08 | 0.01 over |
| Manganese, max | 2.00 | 0.04 over | 2.00 | 0.04 over | 2.00 | 0.04 over |
| Phosphorus, max | 0.20 | 0.010 over | 0.20 | 0.010 over | 0.045 | 0.010 over |
| Sulfur | 0.15, min | .020 | 0.06, max | 0.010 over | 0.030, max | 0.005 over |
| Silicon, max | 1.00 | 0.05 over | 1.00 | 0.05 over | 1.00 | 0.05 over |
| Nickel | 8.0-10.0 | 0.10 | 8.0-10.0 | 0.10 | 10.0-14.0 | 0.15 |
| Chromium | 17.0-19.0 | 0.20 | 17.0-19.0 | 0.20 | 16.0-18.0 | 0.20 |
| Molybdenum | - | - | 2.00-3.00 | 0.10 | ||
| Selenium | - | 0.15-0.35 | - | - | ||
| Titanium | - | - | - | - |
ASTM A320 B8LN, B8LNA
| Type | Austenitic Steels, Classes 1, 1A, and 2 | |||
|---|---|---|---|---|
| Identification | B8LN, B8LNA | |||
| Grade | Unstablilized 18 Chromium-8 Nickel with Nitrogen (AISI Type 304N with restricted Carbon) | Unstabilized 18 Chromium-10 Nickel-2 Molybdenum with Nitrogen (AISI Type 316N with restriced carbon) | ||
Element | Range | Tolerance +/- | Range | Tolerance +/- |
| Carbon, max | 0.030 | 0.005 over | 0.030 | 0.005 over |
| Manganese, max | 2.00 | 0.04 over | 2.00 | 0.04 over |
| Phosphorus, max | 0.045 | 0.010 over | 0.045 | 0.010 over |
| Sulfur, max | 0.030 | 0.005 over | 0.030 | 0.005 over |
| Silicon, max | 1.00 | 0.05 over | 1.00 | 0.05 over |
| Nickel | 8.0-10.5 | 0.15 | 10.0-14.0 | 0.15 |
| Chromium | 18.0-20.0 | 0.20 | 16.0-18.0 | 0.20 |
| Molybdenum | - | - | 2.00-3.00 | 0.10 |
| Nitrogen | 0.10-0.16 | 0.01 | 0.10-0.16 | 0.01 |
Why Lightning Bolt for ASTM A320 Fasteners?
Lightning Bolt & Supply has been servicing North America’s industrial fastener needs for over 25 years. Since then, our focus on the production of high quality parts at competitive pricing has allowed us to become an industry leader. Our niche in exotic high nickel alloy fasteners include materials such as: hastelloy, Inconel, monel, A-286, 904L, Alloy-20, duplex stainless as well as many additional alloys.
Being centrally headquartered in Baton Rouge, Louisiana, we are capable of shipping to jobsites all over the world. Many of our industrial projects that we supply material to include anchor bolts, and also stud bolts of many different ASTM grades. These include B7, L7, B16, B8, B8M, stain hardened and many more. In addition to being an ISO certified fastener manufacturer, we were awarded “Corporate Supplier of the Year” by WBENC.
