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4340 HR Alloy Bar

HR 4340 steel bar is a nickel-chromium-molybdenum medium carbon alloy steel that is known for its toughness. This steel grade also has excellent ductility and strength compared to other alloy steels. 4340 HR bar has a good impact, wear, and abrasion resistance properties in a hardened condition. This grade is often because it provides hardenability and strength that other steel grades cannot provide. Eaton Steel Bar Company stocks many diameters of 4340 hot rolled steel to meet the markets demand. We also supply 4340 steel bar to various industries like aerospace, automotive, construction, and tooling.

4340 hot-rolled-steel-bar

4340 HR Steel Bar Applications

Typical applications for this grade include axle shafts, heavy duty shafting, mine drilling parts, and aerospace parts.

Shapes and Sizes

Eaton Steel Bar Company supplies 4340 steel bar in a variety of sizes ranging from 1/2”-15”. The shapes available for this grade include:

  • Rounds

Standard "4340 Grade" Chemical Composition

Carbon 0.38-0.43
Manganese 0.60-0.80
Phosphorus (max) 0.035
Sulfur (max) 0.040
Silicon 0.15-0.35
Nickel 1.65-2.00
Chromium 0.70-0.90
Molybdenum 0.20-0.30


Estimated Mechanical Property Ranges for "Grade 4340"

Tensile strength (psi) 105,000 - 115,000
Yield strength (psi) 75,000 - 85,000
Elongation in 2” (%) 20 - 30
Reduction of area (%) 35 - 45
Brinell Hardness (BHN) 210 - 240