3312

AISI/SAE 3312 a 3 ½% Nickel-Chromium Case Hardening Alloy Steel
Typical Analysis
C Mn P S Si Ni Cr
.11 .47 .010 .002 .27 3.33 1.47
Characteristics
  • High alloy carburizing grade for those heavy-duty applications requiring high core strength, toughness and fatigue resistance over and above the widely used AISI 8620. Core strengths in the order of 170,000 psi (1172 N/mm2) are attainable. It is the preferred grade for carburized parts in severe operating conditions with excellent low-temperature properties. 3312 may also be used in the heat treated, non-carburized condition for many applications requiring extra strength and toughness. It is normally supplied in the annealed condition and hardness HB 212 would be typical.
Typical Applications
  • Heavy-duty gears, pinions, spline shafts, piston pins, transmission components, rock drilling bit bodies, plastic molds, etc.
Typical Heat Treatment
  • Forging
    • Commence 1215℃ max.
    • Finish 925℃ Bury in Mica.
  • Annealing
    • 840℃ Furnace cool
  • Normalizing
    • 900℃ Air cool
  • Hardened & Tempered (Uncarburized) - Heat to 815℃/ 840℃ and oil quench or Heat to 840℃/ 870℃ and air quench, then temper at 200℃/ 650℃ according to properties required.
  • Case Hardening - single refining treatment. After carburizing at 900℃/ 925℃, cool to RT. Reheat to 775℃/ 800℃, oil quench and temper at 200℃.
Mechanical Properties
  • Typical as supplied, Annealed.
  • Tensile Strength – 102,000 psi
    • 2Tensile Strength – 704 N/mm
  • Yield Strength - 80,000 psi
    • 2Yield Strength – 552 N/mm
  • Elongation - 24%
  • Reduction of Area - 65%
  • Hardness - HB 212
  • Machinability - 40
AISI/SAE 3312 Mechanical Properties - UNCARBURIZED (Hardened & Tempered)
Size - inches 1" Dia 4" Dia
Tensile Strength, psi 136,000 131,500
Tensile Strength, N/mm² 938 907
Yield Strength, psi 117,500 108,000
Yield Strength, N/mm² 810 745
Elongation (%) 19 17
Reduction of Area (%) 63 57
Izod Ft./Lbs. 83 68
Izod Joules 113 92
HB of Core 293 285
AISI/SAE 3312 Mechanical Properties - CARBURIZED - Single refining (Hardened & Tempered)
Size - inches 1" Dia 4" Dia
Tensile Strength, psi 173,000 152,000
Tensile Strength, N/mm² 1,193 1,048
Yield Strength, psi 132,000 109,000
Yield Strength, N/mm² 910 752
Elongation (%) 20 23
Reduction of Area (%) 60 63
Izod Ft./Lbs. 60 63
Izod Joules 81 89
HB of Core 341 311
Hardness of Case HRC 62 60

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