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ASTM A320

ASTM A320 is used in low temperature application, these are available in various types, like stud bolts, heavy hex bolts, hex bolts which are forged or not forged. The main application and areas where this is used is in pipe lines, valves, and pipe fittings and flange joints in piping application. These are generally manufactured similar to A 193 and are available in 8UN threads from 1" diameter and above.

Below we have mentioned the grades that fall under A320.

A320 Typical Grades

L7 AISI 4140/4142 Quenched and tempered
L7M Chromium, Molybdenum, Alloy Steel Quenched and tempered
L43 AISI 4340 Quenched and tempered

A320 Mechanical Requirements

Grade Size Tensile ksi, min Yield ksi, min Elong %, min RA % min HBW Rockwell
L7 Up to 2-1/2 125 105 16 50 321 Max 35 Max
L7M Up to 2-1/2 100 105 16 50 321 Max 35 Max
L43 Up to 4 125 105 16 50 321 Max 35 Max

A320 Chemical Properties

Element L7 (AISI 4140) L7M L43 (AISI 4340)
Carbon 0.38 - 0.48% 0.38 - 0.48% 0.38 - 0.48%
Manganese 0.75 - 1.00% 0.75 - 1.00% 0.75 - 1.00%
Phosphorus, max 0.035% max 0.035% max 0.035% max
Sulfur, max 0.04% max 0.04% max 0.04% max
Silicon 0.15 - 0.35% 0.15 - 0.35% 0.15 - 0.35%
Chromium 0.80 - 1.10% 0.80 - 1.10% 0.70 - 1.10%
Nickel - - 1.65 - 2.00%
Molybdenum 0.15 - 0.25% 0.15 - 0.25% 0.20 - 0.30%

A320 Compatible Nuts & Washers

Bolt Grade Nut Washers
L7 A194 Grade 4 or 7 F436
L7M A194 Grade 7M F436
L43 A194 Grade 4 or 7 F436