AISI 4340 Steel / 36CrNiMo4 / 1.6511 / EN24 / 817M40 / SNCM439

AISI 4340 Steel / 36CrNiMo4 / 1.6511 / EN24 / 817M40 / SNCM439

AISI 4340 steel is a medium carbon, low alloy steel known for its toughness and strength in relatively large sections. AISI 4340 is also one kind of nickel chromium molybdenum steels. 4340 alloy steel is generally supplied hardened and tempered in the tensile range of 930 – 1080 Mpa.

Details zum Produkt

AISI 4340 Steel Specification and Relevant Standards

CountryUSABritainBritainJapan
StandardASTM A29EN 10250BS 970JIS G4103
Grades434036CrNiMo4/
1.6511
EN24/817M40SNCM 439/SNCM8

ASTM 4340 Steels And Equilvalents Chemical Composition

StandardGradeCMnPSSiNiCrMo
ASTM A2943400.38-0.430.60-0.800.0350.0400.15-0.351.65-2.000.70-0.900.20-0.30
EN 1025036CrNiMo4/
1.6511
0.32-0.400.50-0.800.0350.035≦0.400.90-1.200.90-1.20.15-0.30
BS 970EN24/817M400.36-0.440.45-0.700.0350.0400.1-0.401.3-1.71.00-1.400.20-0.35
JIS G4103SNCM 439/SNCM80.36-0.430.60-0.900.0300.0300.15-0.351.60-2.000.60-1.000.15-0.30

AISI Alloy 4340 Steel Mechanical Properties

Mechannical Properties

(Heat Treated Condition )

ConditionRuling section
mm
Tensile Strength MPaYield Strength
MPa
Elong.
%
Izod Impact
J
Brinell
Hardness
T250850-10006351340248-302
T150850-10006651354248-302
U100930-10807401247269-331
 
V631000-11508351247293-352
W301080-12309251141311-375
X301150-130010051034341-401
 
Y301230-138010801024363-429
Z301555-1125510444-

Thermal Properties

PropertiesMetricImperial
Thermal expansion co-efficient (20°C/68°F, specimen oil hardened, 600°C (1110°F) temper12.3 µm/m°C6.83 µin/in°F
Thermal conductivity (typical steel)44.5 W/mK309 BTU in/hr.ft².°F

Forging of 4340 Alloy Steel

Preheat the steel 4340 first, heat up to 1150°C – 1200°C maximum for forging, hold until temperature is uniform throughout the section.

Do not forge below 850 °C. 4340 has good forging characteristics but care must be taken when cooling as the steel shows susceptibility to cracking. Following forging operation the work piece should be cooled as slowly as possible. And cooling in in sand or dry lime is recommended etc.

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