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4340 from Sullivan Steel

4340

4340 is a nickel-chromium-molybdenum, case-hardening martensitic steel with excellent ductility, toughness, and strength properties, as well as high hardenability.


Melt-type(s): VAR
Other name(s): MLX 17
Comparable grade(s): 4140, 4130, 300M

STANDARDS

Type Specifications
AMS AMS 6414, AMS 6415, AMS-STD-2154
UNS G43400, G43406
EN/DIN 34CrNiMo6, 36CrNiMo4, 40NiCrMo7, 40NiCrMo8-4, 50NiCRMo6, 40NCD7, E40NCD7
EN 1.6511, 1.6562, 1.6565, 1.6582

SIZES AVAILABLE

Form Size range
Bar 0.3125" - 8.000"
Tube 3.967" - 10.457"

CHEMICAL COMPOSITION

Element Range (%)
C 0.37 - 0.43
Cr 0.70 - 0.90
Fe 95.20 - 96.33
Mn 0.60 - 0.80
Mo 0.20 - 0.30
Ni 1.65 - 2.00
P 0.04 max
S 0.04 max
Si 0.15 - 0.30

CHARACTERISTICS

High temperature Stainless Through-hardened Nitriding Carburizing Induction

CHARACTERISTICS

Characteristic Value
High temperature
Stainless
Through-hardened
Nitriding
Carburizing
Induction

ADDITIONAL INFO

Nickel content in 4340 provides improved strength compared to other low alloy steels, such as 4140. Typically, 4340 is ideal for parts with large cross-sections.

Heat Treatment
Heat treatment instructions and recommendations for 4340 are provided by one of our mills, Carpenter. Please contact Sullivan Steel for additional guidance or information.
Machinability
Sullivan Steel typically stocks 4340 in the normalized and tempered condition, optimal for machinability and heat treatment uniformity. Exceptions may apply. Machining 4340 after heat treatment is generally not recommended.
Common Applications
Gears, shafts, flanges, die blocks, pressure vessels, fasteners, large cross-section components, bearing cages.

RESOURCES

Carpenter Data Sheet: Microsoft Word - 4340.doc

DISCLAIMER

The product information provided on this page is provided for general reference only and is not complete. Customers and prospective customers should rely on the applicable material certifications for product information, including any exceptions to specifications, if applicable. Material certifications are available upon request. All product sales are subject to Sullivan Steel’s standard terms and conditions of sale.