Alloy Steel 4340

Grade Summary: This steel can obtain much deeper harden-ability than 4100 series steel. High strength in heavy sections is possible with maximum toughness and ductility. This material has a high fatigue/tensile ratio and maintains strength, ductility, and toughness at relatively high temperatures. Also has excellent non-distorting properties for an alloy steel.

Typical Applications: Crank shafts, axle shafts, dies, subs, gear shafts, gears, mine drilling parts, oil well fishing tools and parts, etc.

Available products: Round Bar and Plate

Typical Chemical Analysis:

  1. * C – .38/.43 Max. *Mn – .60/.90 *P – .035 Max. *S – .04 Max.
  2. *Si – .15/.35 *Cr – .70/.90 *Mo – .20/.30 *Ni – 1.65/2.00

Typical Mechanical Properties**

Tensile Strength (PSI) 110,000
Yield Point (PSI)  66,000
Elongation*** 23
Brinell Hardness 197

* Chemical Analysis will vary on each heat number

** Ranges shown are for 4340 Annealed- All values are minimum values and are representative.

*** % in 2”

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