42crmo vs 4140

42CrMo and 4140 are both widely used alloy steels that have similar chemical compositions and mechanical properties. Here's a comparison between 42CrMo and 4140:

Chemical Composition:

42CrMo: It is a Chinese standard grade, also known as GB/T 3077-1999, with the following composition:

Carbon (C): 0.38-0.45%

Silicon (Si): 0.17-0.37%

Manganese (Mn): 0.50-0.80%

Phosphorus (P): ≤0.035%

Sulfur (S): ≤0.035%

Chromium (Cr): 0.90-1.20%

Molybdenum (Mo): 0.15-0.25%

4140: It is an American standard grade, commonly referred to as AISI 4140 or ASTM A29/A322, with the following composition:

Carbon (C): 0.38-0.43%

Silicon (Si): 0.15-0.35%

Manganese (Mn): 0.75-1.00%

Phosphorus (P): ≤0.035%

Sulfur (S): ≤0.040%

Chromium (Cr): 0.80-1.10%

Molybdenum (Mo): 0.15-0.25%

Mechanical Properties:

Both grades have high strength and good toughness, making them suitable for various applications.

Yield Strength:

42CrMo: ≥930 MPa (min)

4140: ≥415 MPa (min)

Tensile Strength:

42CrMo: 1080-1230 MPa

4140: 655-1030 MPa

Hardness:

42CrMo: 229-269 HB (Annealed) / 293-352 HB (Tempered)

4140: 197-235 HB (Annealed) / 217-235 HB (Quenched and Tempered)

Applications:

Both grades are commonly used for various applications requiring high strength, good toughness, and wear resistance. They are often used in industries such as automotive, oil and gas, construction, and engineering.

While 42CrMo is a Chinese standard grade and 4140 is an American standard grade, the chemical composition and mechanical properties are relatively similar. However, there may be slight differences due to variations in manufacturing processes or specific requirements by different standards. It is recommended to refer to the respective standards or consult with material experts for precise specifications and suitability for specific applications.