Is 42CrMo4 the same as 4140?

42CrMo4 and 4140 are essentially the same steel grade. Both refer to a low-alloy, high-strength steel that belongs to the family of chromium-molybdenum steels.

42CrMo4 is the European designation according to the EN 10083 standard, while 4140 is the American designation according to the AISI/SAE system. The numerical values "42" and "40" in the respective designations represent the approximate carbon content of the steel (0.42% and 0.40%).

These grades are widely used in various industries, including automotive, aerospace, oil and gas, and machinery, due to their excellent combination of strength, toughness, and hardenability. They offer good fatigue resistance, high tensile strength, and good impact properties.

While the chemical composition and mechanical properties of 42CrMo4 and 4140 are similar, there may be slight differences in specific tolerances or regional variations based on the manufacturing standards and processes followed in different countries. It's important to consult the relevant standards or specifications and consider any specific requirements of the application when selecting between these two designations.