AIS4340 is a high-strength nickel-chromium-molybdenum alloy steel with superior hardenability and outstanding comprehensive mechanical properties. After quenching and tempering treatment, it delivers ultra-high tensile strength, excellent toughness, impact resistance and fatigue performance. It maintains stable structural strength under heavy load and complex stress conditions, and is widely used in aerospace parts, high-load shafts, gears, heavy machinery components and high-strength fasteners.

Advantage

1.Excellent deep hardenability, uniform internal and external hardness for large section parts 2.Ultra-high strength and toughness combination, far better than ordinary alloy steel 3.Outstanding fatigue resistance and impact toughness for severe dynamic load environments 4.Stable heat treatment performance and reliable dimensional stability after processing

Ingredient

• C
• 0.38 ~ 0.43
• Ni
• 1.65 ~ 2.00
• Cr
• 0.70 ~ 0.90
• Mo
• 0.20 ~ 0.30
• Mn
• 0.60 ~ 0.85
• Si
• 0.15 ~ 0.35
• P
• ≤0.035
• S
• ≤0.040
• Fe
• Balance

Standard

• USA
• ASTM A322 / AISI 4340
• China
• GB/T 3077‑2015、GB/T 4356‑2021

Mechanics

• STATE
• RP
• YIELD
• EXTEND
• SHRINK
• HARDNESS
• IMPACT
• Annealed
• ≥1080 MPa
• ≥980 MPa
• ≥12 %
• ≥45 %
• ≤330 HBW
• ≥25 J
• Annealed
• ≥1040 MPa
• ≥940 MPa
• ≥12 %
• ≥45 %
• ≤330 HBW
• ≥25 J

• STATE
• Annealed
• RP
• ≥1080 MPa
• YIELD
• ≥980 MPa
• EXTEND
• ≥12 %
• SHRINK
• ≥45 %
• HARDNESS
• ≤330 HBW
• IMPACT
• ≥25 J
• STATE
• Annealed
• RP
• ≥1040 MPa
• YIELD
• ≥940 MPa
• EXTEND
• ≥12 %
• SHRINK
• ≥45 %
• HARDNESS
• ≤330 HBW
• IMPACT
• ≥25 J