45Mn2 
 45Mn2, alloy structural steel. Standard: GB / T 3077-1999 
 [] The main features of carbon steel is quenched and tempered steel, strength, wear resistance and hardenability were higher in the hardenability of the oil in the critical diameter of 10 ~ 25mm, the critical quenching diameter in water of 22 to 45. Tempered with good mechanical properties, can still cutting good; but when overheating heat sensitivity and tendency to temper brittleness, water quenching easy to crack, white point sensitive welding and cold plastic deformation and low defects. 
 [Application examples] This steel is generally used in the quenched state can also be used in normalizing the state, suitable for manufacturing high stress and wear conditions in the work of the parts. When the workpiece diameter is less than 60mm, the performance and the 40Cr steel quite. Tractors and general machinery in the automotive manufacturing, for the manufacture of universal joint shafts, axles, connecting rod cap, friction plate, worm, gear, gear shaft, shaft tram and steam locomotive, carriage shafts, heavy-duty rack and cold-drawn state bolts and nuts, etc. 
 Chemical composition 
 [Chemical composition] (wt) (%) Carbon C: 0.42 ~ 0.49 Si Si: 0.17 ~ 0.37 Manganese Mn: 1.40 ~ 1.80 S S: to allow the residual phosphorus content of ≤ 0.35 P: ≤ 0.35 to allow the residual content of chromium Cr: to allow the residual content ≤ 0.30 Ni: to allow the residual copper content of ≤ 0.30 Cu: ≤ 0.30 to allow the residual content 
 45Mn2 
 Mechanical Properties 
 [Mechanical Properties] sample blank size (mm): 25 Heat treatment: first quenching temperature (℃): 840; Coolant: Oil second quenching temperature (℃): - tempering heating temperature (℃): 550 ; coolant: water, oil and tensile strength (σb / MPa): ≧ 885 Yield point (σs / MPa): ≧ 735 Elongation (δ5 /%): ≧ 10 section shrinkage (ψ /%): ≧ 45 impact absorbed energy (Aku2 / J): ≧ 47 Brinell hardness (HBS100/3000) (annealing or tempering state): ≦ 217 
 45Mn2