ASTM A320 L7

LoneStar Fasteners provide ASTM A320 L7 grade solutions to best meet your requirements.

ASTM A320 L7 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, predominantly but not exclusively up to 2 ½” in diameter.

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 to the additional requirements of API 20E BSL 1, 2 and 3.


ASTM A320 L7: Forms

  LoneStar Manufacture 
Stud Bolts
Hexagon Headed Bolting
Socket Headed Bolting
Double Ended and Waisted Studs
Associated OEM Parts

ASTM A320 L7: Sizes and Threads 

  LoneStar Manufacture 
Metric Coarse
Metric Fine
Imperial UNC
Imperial 8UN
Imperial UNF
Metric sizes available Up to M100
Imperial sizes available Up to 6.00″

ASTM A320 L7: 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 %
Molybdenum 0.15-0.25 %

ASTM A320 L7: Mechanical Properties

2.1/2″ and under Over 2.1/2″ to 4″ Over 4”
Tensile Strength Min, Ksi (MPa) 125 (860) 110 100
Yield Strength  min, 0.2% offset Ksi (MPa) 105 95 85
Elongation in min% 18 17 16
Reduction of Area min% 50 45 45
Hardness Max 321 HBW 321 HBW 321 HBW
Hardness Max 35 HRC 35 HRC 35 HRC

ASTM A320 L7: Impact Properties

Test Temperature °F (°C) -150 (-101)
Average impact toughness, min, ft-lbf (J) 20 (27)
Average impact toughness, min, ft-lbf (J) 15 (20)

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