Learn more about the forms, sizes, and properties of our ASTM A320 L7M solutions below.

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.


ASTM A320 L7M: Forms

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

ASTM A320 L7M: 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 L7M: 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 L7M: 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

ASTM A320 L7M: 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)


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