Chemical composition:
Chemical Composition
C Si Mn P S Ni Cr Cu
≤
40 0.37 to 0.44 0.17 to 0.37 0.50 to 0.80 0.30 0.25 0.25 0.035 0.035
45 0.42 to 0.50 0.17 to 0.37 0.50 to 0.80 0.30 0.25 0.25 0.035 0.035

Mechanical properties:
Grades blank sample
Size
/ mm heat treatment process of the mechanical properties of the steel hardness delivery status
/ HBS
Normalizing quenching and tempering σb / MPa σs / MPa δ5 (%) ψ (%) Ak / J ≤
≥ No heat annealed steel
40 25 8,608,406,005,703,351,945 47 217 187
45 25 8,508,406,006,003,551,640 39 229 197

Characteristics and Uses:
40: used in the manufacture of machinery moving parts, such as rollers, shafts, connecting rods, discs and so on. And train axles, but also for cold drawing, plate, strip, seamless tube.
45: for the manufacture of steam turbines, compressors, pumps moving parts; also replace carburizing steel gears, shafts, piston pins and other parts (parts subject to high or flame surface hardening); and can be used as the casting .