4330 MOD Alloy Steel - AMS 6411 VAR - UNSK23080

4330 MOD VAR AMS 6411 is AISI 4330 Steel modified with the addition of Vanadium. It is a low alloy steel capable of being heat treated to high strength levels. Vanadium is added to improve impact strength and hardenability. This is a premium aircraft quality steel usually produced as a consumable electrode remelted product (VAR). AMS 6411 also allows the 2nd melt to be ESR (Electro-Slag Remelting) when specified by the end-user.

4330 Steel Round Bar
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Service Steel Aerospace is one of the largest distributors / suppliers of 4330 Alloy Steel available in multiple forms including round bar and block. See below for product size ranges stocked.

4330 Mod VAR Alloy Steel Applications:

Aerospace applications are those requiring high tensile strength and good ductility, coupled with high impact strength, superior transverse properties, and hardness. The carbon content lower than AISI 4340 makes this grade useful for applications that involve shock loading or stress concentration.

Common Trade Names:

  • 4330+V
  • 4330 CEVM
  • 4330 Modified
  • 4330M
  • Lescalloy 4330+V VAC-ARC
  • 4330V
  • SAE 4330M
  • 34CrNiMo6V
  • HS220-27 Alloy Steel

Common Specifications:

  • AMS 6411
  • AMS 6427 except VAR
  • BMS 7-122
  • BMS 7-27 except VAR
  • MIL-S-8699
  • EMS 96242
  • CE 0906
  • FMS 1012
  • GM 1010

Stocked Sizes:


Note: Stocked as Normalized & Tempered (N&T)
  • Rounds: Rough Turned (RT) N&T:
    • 33 Diameters 0.500" through 10"
  • Blocks (Bars): Forged, Machined 4 sides N&T
    • Stocked sizes
      • 12" x 23" or smaller
      • Custom thicknesses & widths available saw-cut

Macrostructure standards:


 Class Condition Severity 
1FrecklesA
2White SpotsA
3Radial SegregationB
4Ring PatternB

Longitudinal Tensile Properties:


PropertyValue
Tensile Strength220 ksi
Yield Strength 0.2% offset185 ksi
Elongation10%
Reduction of Area35%

After heat treating specimens per paragraph 3.4.5

Chemical Composition:


SymbolElementMin %Max %
CCarbon0.28%0.33%
MnManganese0.65%1.00%
SiSilicon0.15%0.35%
PPhosphorus0.015%
SSulfur0.015%
CrChromium0.75%1.00%
NiNickel1.65%2.00%
MoMolybdenum0.35%0.50%
VVanadium0.05%0.10%
CuCopper0.35%

Fabrication


Forging1950° – 2255° F (1066° – 1235° C)
MachinabilityNormalize & temper at 1250° F (675° C) prior to machining. Machining at max strength is usually followed by stress relieving
WeldingArc or Resistance Flash weldable

Physical Properties:


  • Density: 0.2836 #/in3

Heat Treatment


Type of Heat TreatingProcess
Normalize1600° - 1700° (870° - 925° C), air cool
Anneal1525° - 1575° (830° - 860° C), furnace cool
HardenAustenitize 1550° - 1600° (845° - 870° C), water, oil, or polymer quench
Temper500° - 700° (260° - 240° C) for tensile 220-240 ksi

Minimum Transverse Tensile Properties per AMS 6411:


Cross-section Area Tensile StrengthYield Strength 0.2% OffsetAvg. Reduction of AreaIndividual Reduction of Area
Up to 144 in2, incl220 ksi185 ksi35%30% min
Over 144 in2 to 225 in2, incl220 ksi185 ksi30%25% min
Over 225 in2220 ksi185 ksi25%20% min

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