Have any questions? Contact us


300M Steel Alloy Round Bar (E4340 Modified)

300M is a “Modified 4340,” with the addition of vanadium and a higher silicon content, it offers a combination of toughness and ductility at high-strength levels. 300M is a deep hardening steel with excellent torque properties, high fatigue and creep characteristics, and maintains its strength at moderately high temperatures. Meets MIL-S-8844, and others.

Typical Mechanical Properties – 300M Bar:

Properties AFTER heat treatment Up to 100 sq in Over 100-144 sq in
Tensile Strength (psi) 280,000 min 280,000 min
Yield Point (psi) 230,000 min 230,000 min
Reduction of Area (%) 30 min 25 min


 Note: “Typical Mechanical Properties” listed in this catalog have been compiled from a variety of sources. Information is deemed reliable, but not guaranteed. Data is provided for information only, NOT FOR DESIGN PURPOSES.

Round Bar DiagramStocked in 11-13 foot random lengths; cut pieces available. Other sizes may be available on request.

.500 .6682
.625 1.044
.875 2.046