Ningbo Ningshing Precision Machinery Group Co., Ltd.Who We AreNo.25 Hongxiang Rd A area Industry, Hongtang Jiangbei, Ningbo, 315033, Zhejiang Province, ChinaFormerly known as Ningbo Ningshing Special-Steel Group Co., Ltd., we are a holding subsidiary of Ningbo Ningshing Holdings Corporation. After years of development, we have successfully realized the transformation of "industry supply chain ecosystem" from only trading to integrated operation, including distribution and retail, precision processing, intelligent manufacturing, vacuum heat treatment, technical services and international trade, etc. As one of the largest special steel distribution enterprises in China with imported and homemade tool steel materials, Ningshing P

AISI 4340 Alloy Steel / 34CrNiMo6 / 1.6582 / SNCM439
AISI 4340 Alloy Steel / 34CrNiMo6 / 1.6582 / SNCM439
AISI 4340 Alloy Steel / 34CrNiMo6 / 1.6582 / SNCM439
AISI 4340 Alloy Steel / 34CrNiMo6 / 1.6582 / SNCM439
AISI 4340 Alloy Steel / 34CrNiMo6 / 1.6582 / SNCM439
AISI 4340 Alloy Steel / 34CrNiMo6 / 1.6582 / SNCM439
AISI 4340 Alloy Steel / 34CrNiMo6 / 1.6582 / SNCM439
AISI 4340 Alloy Steel / 34CrNiMo6 / 1.6582 / SNCM439
AISI 4340 Alloy Steel / 34CrNiMo6 / 1.6582 / SNCM439

AISI 4340 Alloy Steel / 34CrNiMo6 / 1.6582 / SNCM439

Model NO.
Alloy steel 1.6582

AISI 4340 Alloy Steel | 34CrNiMo6 | 1.6582 | SNCM439

Ningbo Ningshing Precision Machinery Group Co., Ltd. is the leading stockist of AISI 4340 alloy steel rounds. We have running stock of solid round bars dia.16-300mm. Annealed or Q+T condition. We can also do furthur machining as per customers' requirement.

AISI 4340 Alloy Steel is a heat treatable and low alloy steel containing chromium, nickel and molybdenum. It has high toughness and strength in the heat treated condition. It is mainly used in power transmission gears and shafts, aircraft landing gear, and other structural parts.

Hot Rolled Round: dia.16-300 mm
Forged Round: dia.150-1200 mm
Cold Drawn Round: dia.6-30 mm
Hot Rolled Plate: 10-150 x 2000-2300 mm
Forged Block: 150-1000 x 200-1900 mm

Delivery Condition
EAF+LF+VD, Hot Rolled or Forged or Cold Drawn, Annealed or Q+T, Black or Machined surface, UT SEP1921 Class3 C/c or D/d


434034CrNiMo6 1.6582 SNCM43940CrNiMoA
Other designations that are equivalent to AISI 4340 alloy steel include the following:
AMS 6359 AMS 6454 ASTM A331 (4340) ASTM A711 SAE J1397 (4340)
AMS 6409 ASTM A29 (4340) ASTM A506 (4340) ASTM A752 (4340) SAE J404 (4340)
AMS 6414 ASTM A320 (L43) ASTM A519 (4340) ASTM A829 SAE J412 (4340)
AMS 6415 ASTM A322 (4340) ASTM A646 (4340-7) MIL S-5000

Chemical Composition (%)

Steel Grade CSiMnPSCrMoNi
34CrNiMo60.30-0.38≤ 0.40 0.50-0.80≤ 0.035 ≤ 0.035 1.30-1.700.15-0.301.30-1.70
43400.38-0.430.15-0.350.60-0.80≤ 0.035 ≤ 0.040 0.70-0.900.20-0.301.65-2.00
SNCM4390.36-0.430.15-0.350.60-0.90≤ 0.030 ≤ 0.030 0.60-1.000.15-0.301.60-2.00
40CrNiMoA0.37-0.440.17-0.370.50-0.80≤ 0.030 ≤ 0.030 0.60-0.900.15-0.251.25-1.65

This low-alloy steel finds many applications where high strength, plasticity required such as large and important parts requiring hardening and tempering as heavy load axle for heavy machinery, axle with diameter over 250mm for steam turbine, axle of rotor wing for helicopter, axle of turbo and turbine blade and heavy load transmission part for jet engine, fasteners and gear for crank axle. It’s also used for rotor spindle and blade where temperature over 400℃. It can be used as important part with special properties after nitriding and ultrahigh strength steel after low tempering isothermal quenching.

Mechanical Properties

Tensile strength 745 MPa 108000 psi
Yield strength 470 MPa 68200 psi
Bulk modulus (typical for steel) 140 GPa 20300 ksi
Shear modulus (typical for steel) 80 GPa 11600 ksi
Elastic modulus 190-210 GPa 27557-30458 ksi
Poisson's ratio 0.27-0.300.27-0.30
Elongation at break 22%22%
Reduction of area 50%50%
Hardness, Brinell 217217
Hardness, Knoop (converted from Brinell hardness) 240240
Hardness, Rockwell B (converted from Brinell hardness) 9595
Hardness, Rockwell C (converted from Brinell hardness. Value below normal HRC range, for comparison purposes only) 1717
Hardness, Vickers (converted from Brinell hardness) 228228
Machinability (annealed and cold drawn. Based on 100 machinability for AISI 1212 steel.) 5050

Thermal Properties

Thermal expansion co-efficient (20°C/68°F, specimen oil hardened, 600°C (1110°F) temper 12.3 µm/m°C 6.83 µin/in°F
Thermal conductivity (typical steel) 44.5 W/mK 309 BTU in/hr.ft².°F

Fabrication & Heat Treatment

AISI 4340 alloy steel can be machined using all conventional techniques. Machining process can be performed in the annealed or normalized and tempered conditions.

AISI 4340 alloy steel has good ductility and formability in the annealed condition. It can be bent or formed by pressing or spinning in the annealed state.

AISI 4340 alloy steel can be welded using fusion or resistance welding methods. Preheat and post heat weld procedures are followed while welding this steel by established methods.

Heat Treatment
AISI 4340 alloy steel is heat treated at 830°C (1525°F) followed by quenching in oil.

AISI 4340 alloy steel is forged at 427 to 1233°C (1800 to 2250°F).

Cold Working
AISI 4340 alloy steel can be cold worked using all conventional methods in the annealed condition. It has high ductility.

AISI 4340 alloy steel is annealed at 844°C (1550°F) followed by cooling the furnace.

AISI 4340 alloy steel should be in the heat treated or normalized and heat treated condition before tempering. Tempering temperatures depend upon the desired strength level.

AISI 4340 alloy steel can be hardened by cold working or heat treatment.

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