S50C medium carbon steel for high strength, low cold plastic deformation, welding performance, poor hardenability, but no temper brittleness, cutting can still be. General normalizing or quenching and tempering the use, requirements for the manufacture of high wear resistance, the role of dynamic load and the impact of small machined parts and spring parts, such as forged gears, levers, rollers, shafts, friction disc, agricultural digging Plowshare, heavy-duty spindle and so on. 

 Chemical composition 
 Carbon C: 0.47 ~ 0.55 

 Si Si: 0.17 ~ 0.37 

 Manganese Mn: 0.50 ~ 0.80 

 S S: ≤ 0.035 

 Phosphorus P: ≤ 0.035 

 Chromium Cr: ≤ 0.25 

 Ni-Ni: ≤ 0.25 

 Copper Cu: ≤ 0.25 

 Mechanical Properties 
 Tensile strength σb (MPa): ≥ 630 (64) 

 Yield strength σs (MPa): ≥ 375 (38) 

 Elongation δ5 (%): ≥ 14 

 Reduction of area ψ (%): ≥ 40 

 Impact energy Akv (J): ≥ 31 (4) 

 Impact toughness αkv (J/cm2): ≥ 39 (4) 

 Hardness: no heat treatment, ≤ 241HB; annealed steel, ≤ 207HB 

 Sample size: Sample size is 25mm 

 Heat treatment 
 Heat treatment specifications: normalizing, 830 ℃; quenching, 830 ℃; tempering, 600 ℃. 

 Microstructure: ferrite + pearlite.