30CrMo, alloy structural steel. Uniform digital code: A30302 
 Chemical composition 
 (Wt) (%) 

 C: 0.26 ~ 0.34 

 Si: 0.17 ~ 0.37 

 Mn: 0.40 ~ 0.70 

 Cr: 0.80 ~ 1.10 

 Mo: 0.15 ~ 0.25 

 P: ≤ 0.035 

 S: ≤ 0.035 

 Ni: ≤ 0.030 

 Cu: ≤ 0.030 [1] 

 Mechanical Properties 
 Sample blank size (mm): 25 

 Heat Treatment: 

 First quenching temperature (℃): 880; coolant: water, oil 

 Second quenching temperature (℃): - 

 Heating temperature (℃): 540; coolant: water, oil 

 Tensile strength (σb / MPa): ≧ 930 


 Yield point (σs / MPa): ≧ 785 

 Elongation (δ5 /%): ≧ 12 

 Reduction of (ψ /%): ≧ 50 

 Impact absorbed energy (Aku2 / J): ≧ 63 [2] 

 Brinell hardness (HBS100/3000) (annealing or tempering state): ≦ 229 

 30crmo heat treatment 
 Annealing annealing No.1 "760 ± 10 ℃ annealing, furnace cooling to 400 ℃ air-cooled. 

 HB220-230 

 Normalizing normalize No.4 860 ± 10 ℃ normalizing, baked cooled. 

 Quenched quenching + tempering No.5 840 ± 10 ℃ quenching water or oil (depending on the product shape complexity) ,680-700 degree tempered. HB <217 

 Quenched quenching + tempering No.6 840 ± 10 ℃ quenching oil, and then 470 degree tempered. HRC41-45 

 Quenched quenching + tempering No.7 840 ± 10 ℃ quenching oil, and then 480 degree tempered. HRC35-45 

 Quenched quenching + tempering No.8 850 ℃ quenching oil, and then 510 degree tempered. HRC38-42 

 Quenched quenching + tempering No.9 850 ℃ quenching oil, and then 500 degree tempered. HRC40-43 

 Quenched quenching + tempering No.10 850 ℃ quenching oil, and then 510 ℃ tempered. HRC36-42 

 Quenched quenching + tempering No.11 850 ℃ quenching oil, and then 560 ℃ tempered. HRC32-36 

 Quenched quenching + tempering No.12 860 ℃ quenching oil, and then 390 degree tempered. HRC48-52 

 Key Features 
 This steel has high strength and toughness, high hardenability, quenching in oil critical diameter 15 ~ 70mm; hot strength of steel is also good, at below 500 ℃ have sufficient high temperature strength, but when its 550 ℃ intensity decreased significantly; when welding alloy elements in the next limit is quite good, but close to the upper limit of welding medium and preheated before welding to be more than 175 ℃; steel cutting can be good, cold plastic deformation of the middle; heat treatment in 300 ~ 350 ℃ the scope of the first temper brittleness; have a tendency to the formation of white spots. 

 Application examples 
 This steel is usually used in the quenched state, when the carbon content of steel can also be used for the minimum requirements of the Department of heart hardened steel with higher strength. Mainly in medium-sized manufacturing machinery for the manufacture of large cross-section, high-stress conditions in the work conditioning parts such as shafts, spindles and control by high load wheels, bolts, studs, gear, etc.; in the chemical industry used to manufacture welded parts, plate and pipe welding structure and composition containing nitrogen and hydrogen in the working medium temperature does not exceed 250 ℃ high-pressure pipe; in turbine and boiler manufacturers in the following work for the manufacture of fasteners 450 ℃, 500 ℃ below by the pressure of the flange and nuts, especially for the manufacturing of 300 atmospheres, 400 ℃ the following working catheter.