Full Transcript:

What’s up guys?!?!?! It’s Michael with Michael Talks Metal back for some more alloy steel talks today!!! 4140 is on the docket so sit down buckle up and get comfortable! Cause we’re off!

Next up in our new series on aircraft quality alloy steels is 4140. Like all 41xx series alloys, Chromium and Molybdenum are key to its performance. With a nominal carbon content of point 40 %, it is capable of higher strength and hardness than 4130. It  can be heat treated to a hardness up to 50 Rc in sections 1/2 inch or less.

It is available in all common product forms.

Chemical Composition for 4140

Chemical Composition4140
ElementMin %Max %

Small variations in these chemistry requirements exist in some specifications.

Typical End Quench Hardenability (EQH):

50 Rc @ 5/16″

44 Rc @ 9/16″

Typical Heat Treatment Temperatures:

Normalize   1600 – 1700  deg F

Austenitize   1525 – 1600 deg F

Temper         700  – 1300  deg F

We have several specs today so here goes with the more common specifications for 4140……

SpecificationProduct FormQualityMeltCondition
AMS 6349Bars2301VDNormalized
AMS 6382Bars, Forgings, Rings2301VDAnnealed
AMS 6529Bars2304VDNormalized
AMS-S-5626Bars, Forgings2301VDSee Spec – Various
MIL-S-5626Bars, Forgings2301VDSee Spec – Various
AMS 6395Sheet, Strip, Plate2301VDSee Spec – Various
AMS 6381Mechanical Tubing2301VDSee Spec

AMS-S-5626 is the current replacement for the former military MIL-S-5626

As always, details in specifications and part requirements can alter what we have shown you here today. So for the 95th time – I won’t forget to tell you toooooo Check the Specs…  Twice! This is Michael with Michael Talks Metal. Thanks for watching and if you stuck around till now, and haven’t subscribed, please click here. If you missed last weeks video, click here. Michlin Metals is a supplier and distributor of 4140 check the website for more info www.michlinmetals.com. Thanks for watching, I will see you next Thursday 10am. I’m out!