SAE AISI 8620 Alloy Steel Chrome Moly Bars

Product Description

SAE AISI 8620 is a low-nickel, chromium-molybdenum, low-carbon alloy steel primarily used as a case-hardening (carburizing) grade. It is designed to develop a high surface hardness while maintaining excellent core toughness, making it the industry standard for parts that must resist both wear and impact.

1. Key Characteristics & Performance

The "86" series designation indicates a triple-alloy steel containing Nickel, Chromium, and Molybdenum.

• Case Hardening: Responds exceptionally well to carburizing, achieving a surface hardness of 55“62 HRC while keeping the core ductile.

• Toughness: The Nickel content ($0.40“0.70\%$) provides superior core toughness compared to similar grades like 8615 or 8617.

• Machinability: Very good in the annealed or normalized state (approx. 65% of AISI 1212). It is often easier to machine than higher-carbon grades like 4140.

• Weldability: Good weldability in the as-rolled condition, though preheating to 200C (400F) is recommended for thicker sections to avoid cracking.

2. Mechanical Properties (Typical)

Properties vary based on heat treatment, but common baseline values for AISI 8620 include:

3. Popular 8620 Bar Options

Because 8620 is a staple engineering steel, it is available in various finishes ranging from rough-forged to precision-polished.

SAE 8620 Round Alloy Steel Bar (6 Meter)

A standard-length industrial bar typically used for high-volume manufacturing of gears and shafts.

• Condition: As-Rolled / Forged

• Best For: Gear blanks and heavy machinery components.

8620 Cold Drawn or Belt Polished Bar

A high-quality finished bar that offers tighter dimensional tolerances and a smoother surface, ideal for precision CNC machining.

• Finish: Cold Drawn / Polished

• Best For: Intricate parts, firearms components, and aircraft pins.

120mm SAE8620 Forged Round Bar

For heavy-duty applications, these larger diameter forged bars provide a more refined grain structure, improving fatigue life in high-stress environments.