30CrMo Round Steel BarHigh strength and toughness, good hardenability, critical quenching diameter in oil ranges from 15 to 70mm; the steel also exhibits good thermal strength, maintaining sufficient high-temperature strength below 500℃, but its strength significantly decreases at 550℃; welding is excellent at the lower limit of alloy elements, but only moderate near the upper limit, requiring preheating to above 175℃ before welding; good machinability, with moderate ductility during cold deformation; exhibits first-class temper brittleness in the range of 300 to 350℃ during heat treatment; prone to form white spots. 30CrMo round steel is typically used in tempered condition; steel with carbon content at the lower limit can also be used as carburizing steel with high core strength. It is mainly used in medium-sized machinery manufacturing for the production of tempered parts with large cross-sections and operating under high stress conditions, such as shafts, mainshafts, and heavily loaded control wheels, bolts, double-end bolts, gears, etc.; in the chemical industry, for manufacturing welded components and structures composed of plates and tubes, and high-pressure conduits working in nitrogen-hydrogen media at temperatures not exceeding 250℃; in the turbine and boiler manufacturing industries, for producing fasteners, flanges, and nuts working below 450℃ and under high pressure below 500℃, particularly suitable for manufacturing conduits working at 300 atmospheres and below 400℃.

Chemical Composition of 30CrMo Round Steel:

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

30CrMo Round Steel Mechanical Properties:

Trial blank size(mm)：25

Heat Treatment:

Initial Quenching Heat Temperature (°C): 880; Coolant: Water, Oil

Dier heat treatment quenching temperature(-): Annealing Heat Temperature (℃): 540; Coolant: Water, Oil

Tensile strength(σb/MPa)：≥930

Yield Point(σs/MPa)：≥785

Ultimate elongation(δ5/%)：≥12

Sectional Area Reduction Ratio(ψ/%)：≥50

Impact Absorption Work(Aku2/J)：≥63

Beloit Hardness(HBS100/3000) (Annealed or High Temperature Annealed Condition) ≤229