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Aircraft Alloy Steel 300M / AISI E4340 Mod (AMS 6417 / AMS 6419)

Technical Data Sheet


Chemical Composition Limits
Weight% C Mn P & S Si Cr Ni Mo V Cu
300M VAR 0.38 - 0.45 0.60-0.90 0.010 1.45-1.80 0.70-0.95 1.65-2 0.30-0.50 0.05-0.10 0.35

Alloy Steel 300M VAR is similar to 4340  with the addition of vanadium and a higher silicon content. Alloy 300M offers a combination of toughness and ductility at high strength levels without an increased carbon content. Alloy 300M VAR is Vacuum arc-remelted for excellent purity. 300M can also be supplied dual certified to the British aerospace standard BS 5155.

Typical Mechanical Properties


Alloy Condition Tensile Strength ksi Yield Strength ksi Elongation % Reduction of Area % Hardness HB
Alloy AMS 6417 Bar Normalised/Tempered - - - - 311 max
Alloy AMS 6417 Bar Hardened/ Tempered & Heat Treated 270 220 8 30 -
Alloy AMS 6419 Bar Normalised/Tempered - - - - 311 Max
Alloy AMS 6419 Bar Normalised/Tempered & Heat Treated 280 230 7 25 -

Heat Treatment
AMS 6419 / AMS 6417 / AMS 6257

300M Var
Normalised 1700°F / 1 hr
Austenitise 1600°F / 1 hr
Quench Oil
Double Temper 575°F / 2 hr twice

Alloy 300M VAR (AISI E4340) is available in Round Bar, Tube and Welding Wire.  For all stock availability contact Sales.

AISI E4340 Modified
AMS 6257 Bars / Forgings N&T
AMS 6417 Vac Melt Bars / tubes
AMS 6419 Bars / tubes
MIL-S-8844 Cl3
BS S155


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Every effort is made to ensure that technical specifications are accurate. However, technical specifications included herein should be used as a guideline only. All specifications are subject to change without notice.