ASTM A320 L7M is manufactured from AISI 4140 base material and is supplied in a quenched and tempered condition. Due to the impact requirements at low temperatures, it is mainly used in a low-temperature environment or application but differs from ASTM A320 L7 due to it having a further temper or stress relief after final machining, to reduce the overall hardness for use in sour/specific applications.
Lonestar can offer this material in a standard condition, or it can be provided with supplementary testing as defined in ASTM A320. This material can also be offered fully in compliance with the additional requirements of API 20E BSL 1, 2 and 3.
Forms
| LoneStar Manufacture | ||
| Stud Bolts | ✓ | |
| Studding | ✓ | |
| Hexagon Headed Bolting | ✓ | |
| Socket Headed Bolting | ✓ | |
| Double Ended and Waisted Studs | ✓ | |
| Associated OEM Parts | ✓ |
Sizes and Threads
| LoneStar Manufacture | ||
| Metric Coarse | ✓ | |
| Metric Fine | ✓ | |
| Imperial UNC | ✓ | |
| Imperial 8UN | ✓ | |
| Imperial UNF | ✓ | |
| ACME | ✓ | |
| Metric sizes available | Up to M100 | |
| Imperial sizes available | Up to 6.00″ |
Chemical Composition
| Carbon | 0.38-0.48 | % |
| Manganese | 0.75-1.00 | % |
| Phosphorus | 0.035 | % Max |
| Sulphur | 0.040 | % Max |
| Silicon | 0.15-0.35 | % |
| Chromium | 0.80-1.10 | % |
| Nickel | – | … |
| Molybdenum | 0.15-0.25 | % |
| Copper | – | … |
| Niobium | – | … |
| Titanium | – | … |
| Vanadium | – | … |
| Aluminium | – | … |
| Nitrogen | – | … |
Mechanical Properties
| 2.1/2″ and under | – | |
| Tensile Strength Min, Ksi (MPa) | 100 (690) | – |
| Yield Strength min, 0.2% offset Ksi (MPa) | 80 (550) | – |
| Elongation in min% | 18 | – |
| Reduction of Area min% | 50 | – |
| Hardness Max | 235 HBW | – |
| Hardness Max | 99 HRB | – |
Impact Properties
| Test Temperature °F (°C) | -100 (-73) | – |
| Average impact toughness, min, ft-lbf (J) | 20 (27) | – |
| Average impact toughness, min, ft-lbf (J) | 15 (20) | – |