AISI 4340

Nickel, Chromium, Molybdenum steel for applications requiring high tensile strength and toughness values, particularly in large cross sections in the quenched and
tempered condition. The addition of Molybdenum prevents the steel from being susceptible to temper brittleness. Higher tensile and yield strength than 4140.

Available Product Shapes

Round Bars

General Information

Property Features

Hardenability: good
Machinability: good
Strength: good

Applications

Technical Data

Chemical Analysis

C	Si	Mn	Ni	Cr	Mo	S	P
0.40	0.25	0.70	1.80	0.80	0.25	0.02	0.02

Nearest Standards

AISI	DIN	BS	UNS
4340	1.6565 / 40NiCrMo6	EN24	G43400

Heat Treatment

Forge	Normalize	Anneal	Stress Relieve	Harden	Temper	Nitride
850-1050 °C, slow furnace cool.	850-880 °C, air cool.	650-700 °C, Cool slowly in controlled furnace.	In the quenched and tempered condition, about 30-50 °C below the tempering temperature. Air cool. In the annealed condition, 600-650oC. Air cool.	830-860 °C, oil quench	540-680 °C hold for 1 hour (min). at temperature, air cool. (see tempering chart).	Suitable for both liquid and gas nitriding.

Downloads

Datasheet 4340 2026

PDF | 93 KB

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