Patriot Bolt machines ASTM A320 Grade L43 fasteners from certified AISI 4340 nickel-chromium-molybdenum bar for large-diameter, low-temperature bolting. L43 keeps 125 ksi minimum tensile strength up to 4 in and is Charpy impact tested at −150 °F.
This page brings together the L43 fasteners we make, the L43 property and impact requirements, and how L43 compares with other alloy steel bolting grades.
A320 L43 at a Glance
- Specification
- ASTM A320 / ASME SA320 Grade L43
- Material
- AISI 4340, UNS G43400
- Strength
- 125 ksi min tensile, 105 ksi min yield (4 in and under)
- Impact test
- Charpy V-notch at −150 °F
- Matching nut
- A194 Grade 7L
- Products
- Stud bolts, heavy hex bolts, nuts
A320 L43 Fasteners We Machine
Choose a product to see its standards and options. Every order ships with mill test reports traceable to the heat.
A320 L43 Stud BoltsFull L43 page
A194 Grade 7 Heavy Hex NutsMatching nut (7L)
L43 Heavy Hex BoltsMade in L43A320 L43 Mechanical Properties
| Diameter | Tensile, min | Yield (0.2%), min | Charpy at −150 °F |
|---|---|---|---|
| 4 in and under | 125 ksi | 105 ksi | 20 ft-lb avg / 15 ft-lb single |
Full chemistry is on the A320 L43 stud bolts page.
L43 vs. Other Alloy Steel Bolting Grades
| Grade | Strength (to 2-1/2 in) | Typical use |
|---|---|---|
| A320 L43 | 125 ksi / 105 ksi to 4 in, impact tested at −150 °F | Large-diameter low-temperature flanges |
| A320 L7 | 125 ksi / 105 ksi, impact tested at −150 °F | Low-temperature flanges to 2-1/2 in |
| A193 B7 | 125 ksi tensile / 105 ksi yield | General flange bolting to about 800 °F |
Compare all grades in the Fastener Materials Matrix.
A320 L43 Fastener FAQ
Why choose L43 over L7?
4340 steel hardens more deeply, so L43 keeps full strength up to 4 in diameter. L7 is listed to 2-1/2 in.
Which L43 fasteners does Patriot Bolt make?
We machine L43 stud bolts, heavy hex bolts and nuts, as well as custom parts made to your drawing.
Which nut goes with L43?
Impact-tested A194 Grade 7 nuts, marked 7L.
Do L43 fasteners come with certifications?
Yes. Patriot Bolt is ISO 9001:2015 certified, and every L43 order includes mill test reports traceable to the heat and a certificate of conformance to your purchase order.
Request a Quote
Send us the product, size, specification and quantity, or upload your drawing. Call (281) 581-0176 or request a quote.