AISI 8620

It is designed to achieve a hard, wear-resistant surface while maintaining a tough and ductile core, making it ideal for components subjected to high surface stresses and impact loads. Commonly used in automotive, aerospace, and heavy machinery industries, AISI 8620 forgings offer a balance of machinability, heat treatability, and cost-effectiveness.

Descriptions

1. Chemical Composition

AISI 8620 contains nickel, chromium, and molybdenum to enhance hardenability, core toughness, and wear resistance. Its low carbon content makes it suitable for carburizing or nitriding processes.

Element	Composition (% by Weight)	Role
Carbon (C)	0.18-0.23	Provides base strength; optimized for carburizing.
Manganese (Mn)	0.70-0.90	Improves hardenability and deoxidizes molten steel.
Silicon (Si)	0.15-0.35	Strengthens ferrite and improves cleanliness.
Nickel (Ni)	0.40-0.70	Enhances core toughness and impact resistance.
Chromium (Cr)	0.40-0.60	Improves hardenability and wear resistance.
Molybdenum (Mo)	0.15-0.25	Increases strength and creep resistance.
Phosphorus (P)	0.035 max	Controlled impurity (minimizes brittleness).
Sulfur (S)	0.040 max	Controlled impurity (improves machinability).
Iron (Fe)	Balance	Base metal.

2. Mechanical Properties

AISI 8620 forgings are typically carburized or heat-treated to enhance surface hardness. Properties vary based on processing methods and case depth.

Property	As-Forged	Carburized &Hardened	Normalized	Test Standard
Tensile Strength	500-650MPa	800-1000 MPa (Core)	600-750MPa	ASTME8
Yield Strength(0.2%offset)	300-450MPa	550-750MPa(Core)	350-500MPa	ASTME8
Elongation (% in 50mm)	20-25%	10-15%(Core)	18-22%	ASTME8
Reduction of Area	50-60%	40-50%(Core)	45-55%	ASTME8
Surface Hardness	170-210HB	58-63 HRC (Case)	200-240 HB	ASTME18
Core Hardness(Brinell)	200-240HB	28-35 HRC	N/A	ASTME10
Impact Toughness(Charpy V)	45-70 J(room temp)	25-45 J(Core)	50-80J	ASTME23