In this post I'll talk about SAE 4340. First let's describe it and then have a look at its material's properties.
What is SAE 4340?SAE 4340 alloy steel is a heat treatable and low alloy steel containing chromium, nickel and molybdenum. It has high toughness and strength in the heat treated condition.
ApplicationSAE 4340 alloy steel is mainly used in power transmission gears and shafts, aircraft landing gear, and other structural parts.
Ok let's start with SAE 4340 Chemical Composition.
P, Phosphorus max.0.040
S, Sulfur max.0.040
Learn more about Chemical Composition.
Now it's the mechanical properties turn:
Yield Strength470 - 1150 MPa
Learn more about Yield Strength.
Tensile Strength690 - 1280 MPa
Learn more about Tensile Strength.
Elongation (min.)12 - 22%.
Learn more about Elongation.
Brinell210 - 360
Learn more about Hardness.
Learn more about Density.
Elastic Modulus190 GPa.
Learn more about Elastic Modulus.
Learn more about Poisson's ratio.
Allowable Stress or Factor of SafetyDepends on the project (And its factor of safety).
Learn more about Allowable Stress or Factor of Safety.
My Material's Ranking ResearchWhile engineers will often look for the cheapest material they can use, I took a different approach to material's selection to help newbie students.
I ranked materials according to their yield strengths and SAE 4340 currently ranks 28 in my yield strength index. This means there are other 27 materials that are more resistant.
Note: I've analysed 162 materials in order to create an yield strength index. Check my material's comparison post for more details.
SAE ClassroomAre you having trouble understanding the basics of SAE?
What is SAE: Classification and specification?
This video will walk you through:
ReferencesASTM A519 and other references.
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Luz, Gelson. SAE 4340 Properties (Chem., Mech. & Rankings). Materials Blog. Gelsonluz.com. dd mmmm. yyyy. URL
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AMS 6359 AMS 6454 ASTM A331 (4340) ASTM A711 SAE J1397 (4340)
AMS 6409 ASTM A29 (4340) ASTM A506 (4340) ASTM A752 (4340) SAE J404 (4340)
AMS 6414 ASTM A320 (L43) ASTM A519 (4340) ASTM A829 SAE J412 (4340)
AMS 6415 ASTM A322 (4340) ASTM A646 (4340-7) MIL S-5000