Full Transcript:

What’s up guys?!?!?! It’s Michael with Michael Talks Metal back for more metal madness today! What’s on the docket you ask? Well, next up in this series on aircraft quality alloy steels is 4340. Like all 43xx series alloys, Chromium, Nickel, and Molybdenum are key to its performance. With a nominal carbon content of point 40 %, it is capable of higher strength and hardness than 4140. It  can be heat treated to a hardness up to 40 Rc in sections 3-1/2 inches or less and higher hardness in thinner material.

It is available in all common product forms.

Chemical Composition for 4340 …….

Chemical Composition4340
ElementMin %Max %

Small variations in these chemistry requirements exist in some specifications.

Typical End Quench Hardenability (EQH):

53 Rc @ 12/16″

50 Rc @ 20/16″

Typical Heat Treatment Temperatures:

Normalize   1650  deg F

Austenitize   1500  deg F

Temper         400 – 500 deg F  or  725  deg F minimum

Tempering between 500 and 725 deg F can result in embrittlement

We have several specs today so here goes with the more common specifications for 4340……

SpecificationProduct FormQualityMeltCondition
AMS 6415Bars, Forgings, Mechanical Tubing2301VDSee Spec – Various
AMS 6484Bars, Forgings, Tubing2301VDNormalized & Tempered
AMS 6414Bars, Forgings, Mechanical Tubing2300CEMSee Spec – Various
AMS 6409Bars, Forgings, Mechanical Tubing2304VDNormalized & Tempered
AMS-S-5000Bars, Forgings2301VDSee Spec – Various
MIL-S-5000Bars, Forgings2301VDSee Spec – Various
AMS 6359Sheet, Strip, Plate2301VDSee Spec – Varrious
AMS 6454Sheet, Strip, Plate2300CEMSee Spec – Varrious

As always, details in specifications and part requirements can alter what we have shown you here today. Video 96, you know what I am going to say!!! Check the Specs! Twice. This is Michael with Michael Talks Metal. Michlin Metals is a supplier and distributor of 4340, check the website for more info www.michlinmetals.com. Thanks for tuning in, still here and haven’t subscribed, click here. If you missed last weeks video, click here. This is Michael with Michael Talks Metal, see you next Thursday, 10am, I’m out!