40CrNiMoA vs ASTM 4340 steel composition, application, and corresponding grades in various countries?

40CrNiMoA vs ASTM 4340 steel composition, application, and corresponding grades in various countries?

40CrNiMoA alloy is a widely used alloy steel with high strength, toughness, and wear resistance. It is widely used in different industrial fields due to its unique performance, especially in the manufacturing of high load mechanical parts and structural components. This article will discuss the corresponding grades, chemical composition, physical properties, heat treatment processes, and application fields of 40CrNiMoA alloy steel in various countries.

brief introduction

40CrNiMoA alloy steel is a medium carbon low-alloy steel with excellent comprehensive mechanical properties. Its main chemical components include chromium (Cr), nickel (Ni), molybdenum (Mo), and manganese (Mn), and the combined action of these elements endows this alloy steel with excellent strength and toughness.

Corresponding steel grade

The comparison between 40CrNiMoA and some similar international steel standards is as follows:

German DIN: 34CRNMO6

United States: 4340 steel

Japan: SNCM439（SNCM8）

UK: 817M40

Italy: 40NiCrMo7

chemical composition

The main chemical components of 40CrNiMoA are:

Carbon (C): 0.37% to 0.44%
Manganese (Mn): 0.50% to 0.80%
Silicon (Si): 0.17% to 0.37%
Nickel (Ni): 1.25% to 1.65%
Chromium (Cr): 0.60% to 1.00%
Molybdenum (Mo): 0.15% to 0.25%
The precise control of these elements is crucial for achieving the required mechanical performance.

The main chemical components of 4340 steel are:

Standard	Grade	C	Mn	P	S	Si	Ni	Cr	Mo
ASTM A29	4340	0.38-0.43	0.60-0.80	0.035	0.040	0.15-0.35	1.65-2.00	0.70-0.90	0.20-0.30

 

physical property

The main physical properties of 40CrNiMoA alloy steel include:

High strength: It has high yield strength and tensile strength.

High toughness: good ductility and impact toughness.
Good wear resistance: The enhanced wear resistance makes it suitable for high load environments.

Heat treatment process

The heat treatment of 40CrNiMoA alloy steel usually includes two steps: quenching and tempering:

Quenching: Heat to 840 ° C to 870 ° C and then rapidly cool in oil.
Tempering: Heat to 450 ° C to 650 ° C to achieve the desired hardness and toughness.
After heat treatment, the microstructure and properties of the material will undergo significant changes.

application area

40CrNiMoA alloy steel is widely used in various mechanical and structural components, such as bearings, high-strength bolts and nuts, gears, crankshafts, machine tool parts, and aerospace components.

conclusion

40CrNiMoA alloy steel has become the preferred material in many high-end mechanical manufacturing fields due to its excellent mechanical properties and adaptability. Through reasonable chemical composition control and precise heat treatment processes, its performance can be further improved to meet more stringent application requirements.