What is the difference between 15CrMo and 42CrMo steel

Both metal materials 15CrMo and 42CrMo steel belong to alloy structural steel. From their names, their carbon content is different. The carbon content of 15CrMo steel is 0.15%, and that of 42CrMo steel is 0.42%.

The difference of chemical composition between 15CrMo and 42CrMo steel:
Chemical composition of 15CrMo steel: C: 0.12 - 0.18, Si: 0.17 - 0.37, Mn: 0.40 - 0.70, Cr: 0.80 - 1.10, Mo: 0.40 - 0.55.
Chemical composition of 42CrMo steel: C: 0.38 - 0.45, Si: 0.17 - 0.37, Mn: 0.50 - 0.80, Cr: 0.90 - 1.20, Mo: 0.15 - 0.25.

Difference of mechanical properties between 15CrMo and 42CrMo steel:
Mechanical properties of 15CrMo steel: tensile strength 440MPa, yield point 295MPa, elongation after fracture 22 (%), reduction of area 60 (%).

Mechanical properties of 42CrMo steel: Tensile strength ≥1080MPa, Yield point 930MPa, Elongation after fracture 12 (%), Reduction of area 45 (%).