4340 Product Guide

Applications | Specifications | Mechanical and Chemical Data | Tolerances

Overview

4340 steel has high strength, toughness, wear resistance, and fatigue strength. It can be machined in all states other than hardened and it is easily welded. Additionally, 4340 can be cold worked easily in the annealed state. This material is typically used in military aircraft, automotive systems, hydraulic parts, machine tools, and a steel crankshafts.

Common Trade Names

UNS G43400, AISI 4340, Alloy Steel

Other Resources

Weight Calculator | Mill Test Reports

Products

4340 Rectangle Bar | 4340 Round Bar | 4340 Sheet/Plate

Applications

Aerospace
Automotive
Tooling

Specifications

AMS
6415

	Annealed	Normalized
Physical Properties 4340
Density	0.284 lb/in3	0.284 lb/in3
Ultimate Tensile Strength	108 ksi	185.9 ksi
Yield Tensile Strength	68.2 ksi	125 ksi
Shear Strength	63 ksi	110 ksi
Shear Modulus	10.7 ksi	11.3 ksi
Hardness Rockwell \| Brinell	B95 \| 217	B100 \| 363
Elongation at Break Percentage	22%	12.2%
Modulus of Elasticity	27,800 ksi	29,000 ksi psi
Reduction of Area Percentage	50%	36.3%
Poisson's Ratio	0.29	0.29
Machinability Percentage	50%	50%
Melting Point	2,580-2,650 °F	2,580-2,650 °F
Specific Heat	1.14 x 10^-1 BTU/lb-°F	1.14 x 10^-1 BTU/lb-°F
Thermal Conductivity	309 BTU-in/hr-ft^2-°F	309 BTU-in/hr-ft^2-°F

Chemistry Information
Element	Percentage
C	0.37 - 0.43
Cr	0.8
Fe	96
Mn	0.7
Ni	1.83
P	0.035 max
S	0.04 max
Si	0.23

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