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 
 Mechanical Properties 
 Sample blank size (mm): 25 Heat treatment: first quenching temperature (℃): 880; coolant: water, oil the second quenching temperature (℃): - tempering heating temperature (℃): 540; cooling agents: water, oil tensile strength (σb / MPa): ≧ 930 Yield point (σs / MPa): ≧ 785 Elongation (δ5 /%): ≧ 12 section shrinkage (ψ /%): ≧ 50 impact absorbed energy (Aku2 / J): ≧ 63 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 normalization 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 and 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 and quenching + tempering No.8 850 ℃ oil quenching, tempering and then 510 degrees. HRC38-42 quenching and quenching + tempering No.9 850 ℃ oil quenching, tempering and then 500 degrees. HRC40-43 quenched quenching + tempering No.10 850 ℃ quenching oil, and then 510 ℃ tempered. HRC36-42 quenched quenching + tempering No.11 quenching oil 850 ℃, 560 ℃ and then tempered. HRC32-36 quenched quenching + tempering No.12 860 ℃ oil quenching, tempering and then 390 degrees. 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; the steam turbine, boiler manufacturing industry for the manufacture of fasteners 450 ℃ the following work,? below 500 ℃ under high pressure flange and nuts, especially for the manufacturing of 300 atmospheres, 400 ℃ the following working catheter.