what is difference between 45# steel and 40Cr, 42CrMo

what is difference between 45# steel and 40Cr, 42CrMo

45# is high quality carbon structural steel, carbon content is 0.42-0.50%, with 610 Mpa tensile strength , and yield point  is 360 Mpa;

45# steel is widely used in machinery manufacturing, mechanical properties of this steel is very good, so it’s generally used as axial parts.

40Cr is alloy structural steel, carbon content is 0.37-0.45%,0.8-1.1% chromium, 1000 Mpa tensile strength, yield strength is 800 Mpa; generally used to parts which can be loaded with large force.

42CrMo also belongs to alloy structural steel, carbon content is 0.38-0.45%, 0.9-1.2% chromium, 0.15-0.25% molybdenum, 1100 Mpa tensile strength, yield point is 950 Mpa .usually used to high reliability & bigger load required parts.