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ASTM A320/A320M Grade L71 Impact Tested Carbon-Molybdenum Bolting
Verified Low-Temperature Performance - AISI 4037 Impact Grade
ASTM A320/A320M Grade L71 represents the impact-tested variant of the L7A specification, providing documented proof of toughness at -100°F through mandatory Charpy V-notch testing. Manufactured from AISI 4037 material with controlled carbon-molybdenum chemistry, L71 offers cost-effective reliability for moderate cryogenic applications while maintaining 125 ksi tensile strength. ASTM A320/A320M Grade L71 is bridges the gap between standard L7A and more expensive nickel-bearing alloys for sub-zero service conditions.
ASTM A320/A320M Grade L71 Stud Bolts Properties
ASTM A320/A320M Grade L71 Stud Bolts Chemical Requirements
Ferritic Steels
| Grade Symbol | Description | C | Mn | P, max | S, max | Si | Mo | |
|---|---|---|---|---|---|---|---|---|
| ASTM A320 L71 | C - Mo (AISI 4037) | Range,% | 0.38 - 0.48 | 0.70 - 0.90 | 0.035 | 0.04 | 0.15 - 0.35 | 0.20- 0.30 |
| Product Variation, % Over or Under | 0.02 | 0.03 | 0.005 over | 0.005 over | 0.02 | 0.02 | ||
ASTM A320/A320M Grade L71 Stud Bolts Mechanical Requirements
Ferritic Steels
| Class and Grade, Diameter, in. [mm] | Heat Treatment | Minimum 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 L71 21/2 [65] and underA | quenched and tempered | 1100 [593] | 125[860] | 105[725] | 16 | 50 | 321 HBW or 35 HRC |
ASTM A320/A320M Grade L71 Stud Bolts Impact Test Requirements
| Grade | Test Temperature | CVN Specimen Section Size, mm | Min 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 L71 | - 100 | - 73 | 10 × 10 | 20 [27] | 15 [20] |
| 10 × 7.5 | 16 [22] | 12 [16] | |||
| 10 × 10 | 20 [27] | 15 [20] | |||
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