30Cr 
 30Cr [1], alloy structural steel. Uniform digital code: A20302 [chemical composition] (wt) (%) Carbon C: 0.27 ~ 0.34 Si Si: 0.17 ~ 0.37 Manganese Mn: 0.50 ~ 0.80 S S: to allow the residual phosphorus content ≤ 0.035 P: ≤ 0.035 to allow the residual content Chromium Cr: 0.80 ~ 1.10 Ni: to allow the residual content ≤ 0.030 Copper Cu: ≤ 0.030 to allow the residual content 
 30Cr 
 [Mechanical Properties] sample blank size (mm): 25 Heat treatment: first quenching temperature (℃): 860; Coolant: Oil second quenching temperature (℃): - tempering heating temperature (℃): 500 ; coolant: water, oil tensile strength σb (MPa): ≥ 885 (90) yield strength σs (MPa): ≥ 685 (70) Elongation δ5 (%): ≥ 11 Reduction of area ψ (%): ≥ 45 Impact energy Akv (J): ≥ 47 impact toughness αkv (J/cm2): ≥ 59 (6) Brinell hardness (HBS100/3000) (annealing or tempering state): ≦ 187 
 [Main Features] This steel and 30 steel compared to strength and hardenability are high in oil up to the critical quenching diameter 8 ~ 34mm, the critical quenching diameter in water up to 19 ~ 56mm. Cold plastic deformation of steel and welding of medium, or high-temperature tempering annealing can be a good cutting. 
 [Application examples] This steel is usually used in the quenched state, can also be used after normalizing for the manufacture of the wear and friction conditions or work load in a great impact on the important parts such as shafts, small shaft balance lever, rocker, rod, bolts, nuts, gears and a variety of roller and so on. In addition, this steel is also used as high-frequency surface hardening of steel, required for the production of high surface hardness and wear resistance of parts