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Overview
Specifications
L7
ASTM A320 L7 is an alloy steel, AISI 4140/4142, quenched and tempered. The ASTM A320 specification covers alloy steel and stainless steel bolting materials for low-temperature service. This standard covers rolled, forged, or strain hardened bars, bolts, screws, studs, and stud bolts used for pressure vessels, valves, flanges, and fittings.
Mechanical Properties
| Grade | Diameter | Tensile (min) | Yield (min) | Elong. (min) | Red. of Area (min) | Hardness (max) |
|---|---|---|---|---|---|---|
| L7 | Up to 2-1/2″ | 125 ksi | 105 ksi | 16% | 50% | 321 HBW |
Chemical Properties
| Element | Carbon | Manganese | Phosphorus (max) | Sulfur (max) | Silicon | Chromium | Molybdenum |
|---|---|---|---|---|---|---|---|
| 4140/4142 | 0.38 – 0.48% | 0.75 – 1.00% | 0.035% | 0.040% | 0.15 – 0.35% | 0.80 – 1.10% | 0.15 – 0.25% |