SAE 8620 alloy steel

Introduction

We manufacture forging ingots, billets, and blooms in alloy steel specifically for SAE 8620, tailored for high-performance carburizing and engineering applications.

SAE 8620 is a low carbon nickel-chromium-molybdenum alloy steel widely used for case hardening applications. It provides an excellent combination of high surface hardness, strong core toughness, and superior fatigue resistance, making it ideal for components subjected to high wear and cyclic loading conditions.

Nickel enhances toughness and impact strength, chromium improves hardenability and wear resistance, while molybdenum increases strength and heat resistance. SAE 8620 also offers good machinability in the annealed condition and excellent dimensional stability after heat treatment, making it one of the most widely used carburizing steels in automotive and heavy engineering industries.

This steel delivers reliable performance, long service life, and cost-effective manufacturing for critical engineering components.

Chemical composition

Element Content (%) Function / effect
Carbon (c) 0.18 – 0.23 Provides surface hardness after carburizing
Manganese (mn) 0.70 – 0.90 Improves strength and hardenability
Silicon (si) 0.15 – 0.35 Enhances strength and elasticity
Nickel (ni) 0.40 – 0.70 Improves toughness and impact resistance
Chromium (cr) 0.40 – 0.60 Improves wear resistance and hardenability
Molybdenum (mo) 0.15 – 0.25 Improves strength and heat resistance
Phosphorus (p) Max 0.035 Impurity; lower content improves toughness
Sulphur (s) Max 0.040 Improves machinability in controlled amounts

Mechanical properties (typical, depending on condition & heat treatment)

  • Tensile strength (core): 950 – 1200 MPa
  • Yield strength: 700 – 900 MPa
  • Surface hardness (after carburizing): 58 – 62 hrc
  • Core hardness: 30 – 40 hrc
  • Impact toughness: high
  • Fatigue resistance: excellent

Heat treatment

  • carburizing: heating between approximately 870 – 930°c to enrich the surface with carbon and enhance wear resistance.
  • quenching: rapid cooling after carburizing to develop a hardened martensitic surface layer.
  • tempering: reheating to relieve internal stresses and improve toughness while maintaining hardness.
  • annealing: applied prior to machining to improve workability.

The heat treatment process can be tailored to achieve the desired case depth and Mechanical properties depending on application requirements.

Key features and benefits

  • excellent case hardening capability
  • high surface wear resistance
  • strong and tough core structure
  • high fatigue strength for cyclic load applications
  • superior toughness due to nickel addition
  • good machinability in annealed condition
  • excellent dimensional stability after heat treatment
  • suitable for forging and precision machining

Typical applications

  • automotive transmission gears
  • shafts and pinions
  • differential gears
  • sprockets and couplings
  • heavy duty machine components
  • forged carburized load-bearing parts
  • aircraft and industrial engineering components

Equivalent steel grades

SAE 8620 has several international equivalents, including:

  • EN353 – case hardening nickel alloy steel
  • 20nicrmo2-2 – european carburizing steel
  • din 1.6523 – approximate equivalent

Why choose SAE 8620 for your application?

SAE 8620 offers an outstanding balance of surface hardness, core toughness, and fatigue resistance. The nickel-chromium-molybdenum alloy system provides excellent hardenability and mechanical reliability. Its consistent heat treatment response and dimensional stability make it a preferred choice for carburized components subjected to high loads and repetitive stress while maintaining cost efficiency.

Comparison table for similar grades

Grade Carbon (%) Key applications Heat treatment Comments
SAE 8620 0.18-0.23 Gears, shafts, automotive parts Carburizing + q&t Widely used carburizing steel
SAE 8617 0.15-0.20 Gears and transmission components Carburizing + q&t Slightly lower carbon variant
En 353 0.17-0.22 Automotive transmission parts Carburizing + q&t Popular european grade
20nicrmo2-2 Similar Heavy duty gears Carburizing + q&t High strength alloy steel

Summary

SAE 8620 is a low carbon nickel-chromium-molybdenum alloy steel optimized for carburized engineering components requiring high surface hardness and strong core strength. It delivers dependable performance, long operational life, and excellent mechanical reliability for automotive and heavy-duty engineering applications.