42CrMo4 Steel: Composition, Characteristics, Limitations, and Applications



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What is 42CrMo4 Steel?

42CrMo4 steel is the one of the frequently used alloy steel that characterized by its high strength, great toughness, and good hardenability. It is certtainly a chromium-molybdenum one that is characterized by the European standard EN 10083-3 The “42” stands for the approximate carbon content which is 0.42% (carbon), while CrMo means chromium (Cr) and molybdenum (Mo) are added as alloying components. This steel is in demand where elevated tensile strength is required, such as in gears, shafts, axles, connecting rods, heavy duty machinery components and so forth. 42CrMo4 steel could be thermally processed to achieve desired mechanical properties, which would include increased hardness and wear resistance. It is normal to supply it in the quenched and tempered condition that produces a hardened microstructure that meets the extreme demands for various applications in car, aircraft, and manufacturing fields.

What Are the Other Names for 42CrMo4 Steel?

The 42CrMo4 steel known for its high strength, toughness, and hardenability bears as many names as international standards and industrial practice have. Refereed to as 1.7225 steel in the European Union, commercially referred to as SCM440 steel in Japan, it is an engineering structural steel. In the United States, the steel is sometimes referred to as 4140 steel, even though it does not entirely correspond in composition, it possesses similar properties and applications. In the end, all trade names are a reference to the same Cr-Mo steel alloy widely used in industries that demand robust materials for such applications like gears, shafts, axles, and heavy duty components of machinery.

The Limitations of 42CrMo4 Steel

Although boasting some outstanding mechanical attributes, 42CrMo4 steel has weak points which also need to be considered. Weldability can be difficult because of its high hardenability, and thus a need for preheating and post-weld heat treatments to avoid the crack formation. Machining might also have some problems especially in the hardened condition since the adjustment of suitable parameters and tool materials would be demanded to be carefully made. On the other hand, the steel steel cost can be high compared to low-alloy steel alternatives because of the alloying of chromium and molybdenum. Compared to plain carbon steels, 42CrMo4 provides a reasonable corrosion resistance, but the corrosion resistance still does not compete with stainless steels or other special alloys. Such limitations put into relief the fact that strict application requirements should be taken into account and that untrimmed components made of 42CrMo4 steel must be used properly for the best performance of these components.

Chemical Composition of 42CrMo4 Steel

42CrMO4 steel is strong, hardenable heat-treatable steel with good machinability, strength, wear resistance, toughness, and poor weldability, recognized as an excellent alternative to expensive alloys, like chrome-nickel and chrome-nickel-molybdenum steels. It is commonly used for parts of automotive, armament, mechanical engineering, and more required to be worn, bent, and load. 

Carbon (C)0.38 – 0.45
Chromium (Cr)0.90 – 1.20
Manganese (Mn)0.60 – 0.90
Molybdenum (Mo)0.15 – 0.30
Phosphorus (P)0.0 – 0.025
Silicon (Si)0.0 – 0.40
Sulfur (S)0.0 – 0.035
Iron (Fe)Balance

The Influence of Chemical Composition on the Properties of 42CrMo4 Steel

The mechanical performance of 42CrMo4 steel is remarked by its chemical composition which mainly contains chromium and molybdenum for yield strength and hardenability. Controlled carbon content provides balance for both the strength and the ductility, while manganese helps in developing the toughness. Silicon enables us to make grains more refined and is also helpful in oxidation resistance. The levels of phosphorus and sulfur are minimised so that nobody would face brittleness and problems with machinability. The optimal composition design that this steel exhibits guarantees it is usable in diverse settings hence the preference for it in sectors like automotive manufacturing and machine building.

Mechanical Properties of 42CrMo4 Steel

Diameter, d mm≤ 1616-4040-100100-160160-250
Thickness, t mm< 88-2020-6060-100100-160
Yield Strength, Mpa≥900≥750≥650≥550≥500
Tensile Strength, Mpa1100-13001000-1200900-1100800-950750-900
Elongation, %≥10≥11≥12≥13≥14
Reduction of area ,%≥40≥45≥50≥50≥55

Physical Properties of 42CrMo4 Steel 

Physical PropertiesMetricEnglishComments
Density7.80 g/cc0.282 lb/in² 
Modulus of Elasticity210 GPa20500 ksi 
Shear Modulus80.0 GPa11600 ksi 
Poissons Ratio0.30.3 
Electrical Properties
Electrical Resistivity0.0000200 – 0.0000250 ohm-cmTypical steel
Thermal Properties
Specific Heat Capacity 0.460 – 0.490 J/g-°C0.110 – 0.115 BTU/lb-°F50.0 – 100 °C/122 – 212 °F
Thermal Conductivity40.0 – 45.0 W/m-K278 – 312 BTU-in/hr-ft²-°FTypical steel

Equivalent Materials of 42CrMo4 Steel














Chemical Composition of 42CrMo VS 4140 VS 42CrMo4(1.7225)

  Chemical Composition %
CountryStandardSteel Grade (Material Number)CSiMnPSCrMo
ChinaGB/T 307742CrMo0.38 to 0.450.17 to 0.370.50 to 0.80≤ 0.030≤ 0.0300.90 to 1.200.15 to 0.25
SAE 41400.38 to 0.430.15 to 0.350.75 to 1.00≤ 0.035≤ 0.0400.80 to 1.100.15 to 0.25
EUEN 10083-342CrMo4 (1.7225)0.38 to 0.45≤ 0.400.60 to 0.90≤ 0.025≤ 0.0350.90 to 1.200.15 to 0.30
EUEN 10083-342CrMoS4 (1.7227)0.38 to 0.45≤ 0.400.60 to 0.90≤ 0.0250,020 to 0,0400.90 to 1.200.15 to 0.30

Processing Methods Suitable for 42CrMo4 Steel

42CrMo4 steel can be machined, subjected to heat treatment, welded, forged, and given surface treatments to get the desirable properties. The machinability of a material allows techniques like drilling and milling to be mostly used. Heat treatment, such as quenching and tempering, is advantageously used to improve the mechanical properties. Welding requres care to avoid cracking. According to the heat, treating strengthens the steel’s microstructure and thus increases its strength and toughness. Shot blasting is a surface treatment that helps to avoid corrosion. Hence, these techniques offer great flexibility in producing components for various industries such as automotive, aerospace, machine, and construction businesses.

Applications of 42CrMo4(1.7225) Steel 

  1. Automotive:
  2. Aerospace:
  3. Medical:
  4. Custom Consumer Products:
  5. Motorcycle:
  6. Trailer:
  7. Bicycle:
  8. Kart:
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