SAE 8622 alloy steel

Introduction

We manufacture forging ingots, billets, and blooms in alloy steel specifically for SAE 8622, tailored for high-performance carburizing and engineering applications.

SAE 8622 is a low carbon nickel-chromium-molybdenum alloy steel designed for case hardening applications where high surface hardness and strong core toughness are required. It offers excellent fatigue strength, wear resistance, and load-bearing capacity, making it suitable for heavy-duty automotive and industrial components.

The presence of nickel enhances toughness and impact resistance, chromium improves wear resistance and hardenability, while molybdenum contributes to strength retention and resistance to tempering softening. SAE 8622 also provides good machinability in the annealed condition and maintains dimensional stability after heat treatment, making it suitable for precision engineered and forged components.

This steel provides reliable performance, durability, and cost efficiency for high-stress mechanical applications.

Chemical composition

Element Content (%) Function / effect
Carbon (c) 0.20 – 0.25 Provides surface hardness and strength 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): 1000 – 1250 MPa
  • Yield strength: 750 – 950 MPa
  • Surface hardness (after carburizing): 58 – 62 hrc
  • Core hardness: 32 – 42 hrc
  • Impact toughness: high
  • Fatigue resistance: excellent

Heat treatment

  • carburizing: heating between approximately 870 – 930°c to increase surface carbon content and improve wear resistance.
  • quenching: rapid cooling after carburizing to produce a hardened martensitic surface layer.
  • tempering: reheating to relieve internal stresses and enhance toughness while maintaining hardness.
  • annealing: used prior to machining to improve machinability.

The heat treatment cycle can be adjusted to achieve desired case depth and Mechanical properties based on application requirements.

Key features and benefits

  • excellent case hardening capability
  • high surface wear resistance
  • strong and tough core structure
  • high fatigue strength under cyclic loading
  • 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
  • heavy-duty sprockets and couplings
  • forged load-bearing components
  • industrial machine parts requiring wear resistance
  • high strength engineering components

Equivalent steel grades

SAE 8622 has several international equivalents, including:

  • 20nicrmo2-2 – european carburizing alloy steel
  • din 1.6523 – approximate equivalent
  • EN353 – similar carburizing steel grade

Why choose SAE 8622 for your application?

SAE 8622 offers higher carbon content compared to SAE 8620, providing improved strength and load-bearing capability while maintaining excellent toughness and fatigue resistance. Its nickel-chromium-molybdenum alloy composition ensures superior hardenability and consistent heat treatment response. This makes SAE 8622 highly suitable for heavy-duty carburized components operating under severe mechanical stress.

Comparison table for similar grades

Grade Carbon (%) Key applications Heat treatment Comments
SAE 8622 0.20-0.25 Gears, shafts, heavy-duty parts Carburizing + q&t Higher strength variant of 8620
SAE 8620 0.18-0.23 Automotive transmission components Carburizing + q&t Widely used carburizing steel
SAE 8617 0.15-0.20 Transmission and load-bearing parts Carburizing + q&t Slightly lower carbon grade
En 353 0.17-0.22 Automotive gears and shafts Carburizing + q&t Popular european equivalent

Summary

SAE 8622 is a low carbon nickel-chromium-molybdenum alloy steel optimized for carburized engineering components requiring enhanced strength, wear resistance, and core toughness. It delivers reliable mechanical performance, long service life, and efficient manufacturability for automotive and industrial applications.