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 Composition | 4340 | |
|---|---|---|
| Element | Min % | Max % |
| Carbon | .38 | .43 |
| Manganese | .65 | .85 |
| Phosphorus | .025 | |
| Sulfur | .025 | |
| Silicon | .15 | .35 |
| Chromium | .70 | .90 |
| Nickel | 1.65 | 2.00 |
| Molybdenum | .20 | .30 |
| Copper | 0.35 |
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……
| Specification | Product Form | Quality | Melt | Condition |
|---|---|---|---|---|
| AMS 6415 | Bars, Forgings, Mechanical Tubing | 2301 | VD | See Spec – Various |
| AMS 6484 | Bars, Forgings, Tubing | 2301 | VD | Normalized & Tempered |
| AMS 6414 | Bars, Forgings, Mechanical Tubing | 2300 | CEM | See Spec – Various |
| AMS 6409 | Bars, Forgings, Mechanical Tubing | 2304 | VD | Normalized & Tempered |
| AMS-S-5000 | Bars, Forgings | 2301 | VD | See Spec – Various |
| MIL-S-5000 | Bars, Forgings | 2301 | VD | See Spec – Various |
| AMS 6359 | Sheet, Strip, Plate | 2301 | VD | See Spec – Varrious |
| AMS 6454 | Sheet, Strip, Plate | 2300 | CEM | See 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!
