4340 - ASTM A 646/A646M-2024

Grade	4340
ASTM Specification or Grade	Grade 7
Corresponding Standard	ASTM A646/A646M-2024 Standard Specification for Premium Quality Alloy Steel Blooms and Billets for Aircraft and Aerospace Forgings
Classification	Alloy Steel

4340 Chemical Element Composition Content (%)

Component	C	Si	Mn	P	S	Cr	Ni	Mo
Minimum Value	0.38	0.2	0.65	-	-	0.7	1.65	0.2
Maximum Value	0.43	0.35	0.85	0.015	0.012	0.9	2	0.3

* If any of the following elements are not specified, the following maximum limits shall apply: Nickel 0.35 %; Chromium 0.20 %; Molybdenum 0.06 %; Copper 0.35 %

4340 Mechanical Properties

Heat Treatment or Condition	Hardness HBW
Annealing	≤285

1 Approximate Comparison Table Processing Titanium and Titanium Alloys

China	Japan	United States	International Organization for Standardization	Germany		France	United Kingdom
GB	JIS	ASTM	ISO	DIN EN/DIN	W-Nr.	NF EN/NF	BS EN/BS
TA9	Class 13	Grade 7	Ti-Pd0.2(c)	Ti3Pd	3.7255	Ti-Pd0.2(c)	Ti-Pd0.2(c)

2 Approximate Comparison Table Structural Alloy Steel

China	Japan	United States	International Organization for Standardization	Germany	France	European Standard		Russia	Sweden	United Kingdom
GB	JIS	ASTM	ISO	DIN EN/DIN	NF EN/NF	EN	Numerical Grade	GOST	SS	BS EN/BS
34CrNi3Mo 34CrNiMo ZG34CrNiMo	SNCM447	4340	36CrNiMo6	34CrNiMo6 GS-34CrNiMo6V	35NCD6	34CrNiMo6	1.6582	36KH2N2MFA 38KH2N2MA 40KHN2MA	2541	817M40

3 Approximate Comparison Table Cast Steel

China	Japan	United States	International Organization for Standardization	Germany	France	European Standard		Russia	Sweden	United Kingdom
GB	JIS	ASTM	ISO	DIN EN/DIN	NF EN/NF	EN	Numerical Grade	GOST	SS	BS EN/BS
ZG34CrNiMo 34CrNi3Mo 34CrNiMo	SNCM447	4340	36CrNiMo6	GS-34CrNiMo6V 34CrNiMo6	35NCD6	34CrNiMo6	1.6582	36KH2N2MFA 38KH2N2MA 40KHN2MA	2541	817M40

4340 Corresponding Standards(Same grade name, different standards)

1	ASTM A29/A29M-2012
	4340 G43400
2	ASTM A 320-2000
	4340 L43
3	ASTM A29/A29M-2005
	4340 G43400
4	SAE J404-2000
	4340 G43400
5	ASTM A320/A320M-2018
	4340 A320 L43
6	ASTM A29/A29M-2020
	4340 G43400
7	ASTM A320/A320M-2021
	4340 A320 L43
8	GB /T 38809-2020
	4340 40CrNi2MoA
9	ASTM A519/A519M-2024
	4340
10	GJB 5063-2001
	4340 40CrNi2MoA
11	ASTM A646/A646M-2024
	4340 Grade 7
12	ASME SA-29/SA-29M-2023
	4340 G43400
13	ASTM A320/A320M-2024(a)
	4340 A320 L43

Note: The data is for reference only! If you have any questions, please fill out "I want to correct it"!