4340 (E4340) Alloy Steel

About 4340 (E4340) Alloy Steel

AISI 4340 (E4340) alloy steel is a medium carbon, low alloy steel known for its toughness and strength. Machining is done typically in the annealed condition. It also offers good ductility in the annealed condition, allowing it to be bent or formed. Fusion and resistance welding is also possible.

4340 (E4340) steel alloy is used primarily for structural applications such as aircraft landing gear, as well as other structural parts like gears, sprockets, chucks, molds, and more.

About AMS 6415 Round Bar
(Cold Finished, Hot Rolled)

AMS 6415 round bar cold finished or hot rolled is one of the richer alloy steels, featuring hardenability with high strength characteristics. This steel is an excellent choice for highly stressed parts intended to operate under severe conditions. It is used for crankshafts, landing gear struts, valves, connecting rods, axle shafts, machine tool arbors, and more.


Typical Chemical Properties (%)

Carbon 0.38/0.43 Sulfur 0.025 max. Molybdenum 0.20/0.30
Manganese 0.65/0.85 Silicon 0.15/0.35 Nickel 1.65/2.00
Phosphorus 0.025 max. Chromium 0.70/0.90 Copper 0.35 max.

4340 (E4340) Plate Specifications (AMS 6359) - Annealed

AMS 6415 Round Bar Cold Finished- Annealed AMS 6415 Round Bar Hot Rolled- Annealed


AISI 4340 (E4340) Aircraft Quality Steel
Cut, Finished, and Delivered Fast!

With the largest stocked inventory of aircraft quality steel, Benedict-Miller delivers the best 4340 (E4340) steel plate or round bar cut and finished to your specifications when you need it.Call 1-908-497-1477 to get a quote and immediate answers to your questions.

Quality Raw Materials
from Prime Stock

Our long-standing relationship with vendors ensures you the highest quality raw materials. Representing only prime stock from world class mills, all our AQ steel is certified to Aerospace Material Specifications (mill certification available upon request).

Our diverse supply chain ensures you get the right material for your projects.



No waiting necessary!
Call 1-908-497-1477 to speak with a knowledgeable, friendly AQ steel specialist who will provide you with a quick quote and immediate answers to your questions. Or place a request for quote online now using our convenient form.

  • Largest stocked inventory for fast delivery
  • Prime stock only, highest quality for reliability, durability
  • Sheet, Plate, or Round Bar
  • AMS certified
  • DFARS compliance
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  • Precision parts cut to your specifications using DXF files
  • ISO Certified
  • No minimum quantities


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