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Grade 4140
ASTM
Specification or Grade		 Grade 12
Corresponding Standard ASTM A646/A646M-2024
Standard Specification for Premium Quality Alloy Steel Blooms and Billets for Aircraft and Aerospace Forgings
Classification Alloy Steel
4140 Chemical Element Composition Content (%)
Component C Si Mn P S Cr Mo
Minimum Value 0.38 0.2 0.75 - - 0.8 0.15
Maximum Value 0.43 0.35 1 0.015 0.012 1.1 0.25
* 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 %
4140 Mechanical Properties
Heat Treatment or Condition
Hardness
HBW
Annealing ≤235
1 Approximate Comparison Table Alloy Steel for Quenching and Tempering
United States International Organization for Standardization Germany France European Standard
ASTM ISO DIN EN/DIN NF EN/NF EN Numerical Grade
4140 42CrMoS4 42CrMoS4 42CD4u 42CrMoS4 1.7227
2 Approximate Comparison Table Processing Titanium and Titanium Alloys
China United States International Organization for Standardization Germany France United Kingdom
GB ASTM ISO Numerical Grade DIN EN/DIN W-Nr. NF EN/NF BS EN/BS
TA10 Grade 12 Ti-0.3Mo-0.8Ni R53400 TiNi0.8 3.7105
R53400 		T-N0.8D
R53400 		Ti-0.3Mo-0.8Ni
R53400
3 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
42CrMo SCM440H 4140
4142 		42CrMo4 42CrMo4 42CD4 42CrMo4 1.7225 35KHM
38KHM 		2244 708M40
CFS11
4 Approximate Comparison Table Structural Alloy Steel
Japan United States
JIS ASTM AISI
SNB7 A193 B7 4140
4142
4145
5 Approximate Comparison Table Steel for Cold Heading and Cold Extrusion
China Japan United States International Organization for Standardization European Standard
GB JIS ASTM ISO EN
ML40CrMo SCM440 4140 42CrMo4 42CrMo4
6 Approximate Comparison Table Steel for Cold Heading and Cold Extrusion
China Japan United States International Organization for Standardization European Standard
YB GB JIS ASTM ISO EN
QML40CrMo ML40CrMo SCM440 4140 42CrMo4 42CrMo4
4140 Corresponding Standards(Same grade name, different standards)
1 ANSI
4140 AISI 4140 G41400
2 ASTM A29/A29M-2012
4140 G41400
3 ASTM A 320-2000
4140 L7M L70 L7
4 ASTM A29/A29M-2005
4140 G41400
5 SAE J404-2000
4140 G41400
6 ASTM A29/A29M-2020
4140 G41400
7 ASTM A866-2014
4140
8 ASTM A519/A519M-2024
4140
9 ASTM A646/A646M-2024
4140 Grade 12
10 ASME SA-29/SA-29M-2023
4140 G41400
11 ASTM A513/A513M-2025
4140
12 ASME SA-513-2023
4140

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