*Always consult your Heat Treater* 
     *Information Provided is General*

4340 is a chromium nickel molybdenum alloy that is widely used for deep hardening constructional steel. It is used at a variety of strength levels and at each level possesses remarkable toughness and ductility. 4340 material with its high alloy content, uniform hardness is developed by heat treatment in relatively heavy sections. High fatigue strength makes E-4340 material ideal for highly stressed parts. 4340 material maintains its strength and hardness at elevated temperatures.

4340 material is available as electric furnace vacuum degassed steel to meet the high aircraft quality standards of AMS 2301. Thus, 4340 is suitable for the fabrication of parts, which may be subjected to magnetic particle inspection.

4340 material is also available as a Premium Aircraft Quality product. The regular aircraft quality material is remelted in a vacuum using consumable electrode practice. This results in a much cleaner steel the magnetic particle test requirements of AMS-2300 and insures a steel of the highest quality with excellent transverse ductility and toughness at high strength levels.

4340 material applications are intended for parts with sections 3 ½” or less in thickness at the time of heat treatment, which require a through-hardening steel capable of developing minimum hardness of RC 30.


 Sizes available upon request


  •  Up to 1” +/- .002 upto .005

  •  1” to under 6” +/- .002 upto .008

  •  6” and over +/- .006 upto .011

 Hardenability:    End quench hardenability values are RC 50 minimum at 20/16” and RC 45 minimum at 32/16”.

 Quench Medium:    Oil, 140°F maximum Air Salt Bath

 Normalize:   1650°F

 Austentize:   1500°F

 Temper:   400 – 500°F for 260,000 psi strength level 725°F minimum for lower levels

 4340 Material In Stock

 Color Code:   RED & YELLOW

 Flat Dimensions

  • 1/2″ x 11.875″ up to 2 1/2 x 11.125″

  • Non-standard sizes, quoted upon request

 Round Dimensions

  • ½” up to 7”

 Other sizes available upon request

 4340 RD Typical Analysis



















 · Slight variations from typical analysis shown may occur in order  to maintain the desired graphitizing potential.