C: 0.26 ~ 0.34 Si: 0.17 to 0.37 of Mn: 0.40 ~ 0.70 Cr: 0.80 ~ 1.10 Mo: 0.15 to 0.25 P: ≤ 0.035 S: ≤ 0.035 Ni: ≤ 0.030 Cu: ≤ 0.0 
 This steel has high strength and toughness, high hardenability, critical oil hardenability diameter 15 ~ 70mm; hot strength of steel is also a good below 500 ℃ high temperature strength, but at 550 ° C strength decreased significantly; alloying elements in the following limited welding is quite good, but close to the upper limit of weldability medium, and the need to preheat before welding to more than 175 ° C; good machinability of steel, cold deformation of the plastic medium; heat treatment in the range of 300 ~ 350 ° C first temper brittleness; the formation of the tendency of the white point. 30crmo picture 


 This steel is usually used in the quenched and tempered condition, when the carbon content of the lower limit of the steel can also be used as a higher strength of the core part of the carburizing steel. Mainly used in the manufacture of a cross section larger medium-sized machinery manufacturing, quenched and tempered parts of the work under high stress conditions, such as axes, spindle load manipulate the wheel bolts, stud bolts, gears, etc.; in the chemical industry used to produce welding parts, sheet and pipe welded structure of high-pressure catheter and does not exceed 250 ° C temperature containing nitrogen and hydrogen media; used to manufacture the fasteners of the work below 450 ℃ in the steam turbine, boiler manufacturing,? below 500 ℃ by the high-pressure flange and nuts, especially suitable for the manufacture of 300 atmospheric pressure below 400 ℃ catheter.