| C | Si | Mn | S | Mo | P | S | Ni/Cu |
| 0.26～0.34 | 0.17～0.37 | 0.40～0.70 | 0.80～1.10 | 0.15～0.25 | ≤0.035 | ≤0.035 | ≤0.030 |
This steel has high strength and toughness, high hardenability, and a critical hardenability diameter of 15-70mm in oil. The thermal strength of the steel is also good, with sufficient high-temperature strength below 500 ℃, but its strength significantly decreases at 550 ℃; When the alloy element is at the lower limit, the welding is quite good, but when it approaches the upper limit, the weldability is moderate, and it needs to be preheated to above 175 ℃ before welding; Steel has good machinability and moderate plasticity during cold deformation; There is a first type of tempering brittleness in the temperature range of 300-350 ℃ during heat treatment; There is a tendency to form white spots.
Mechanical manufacturing
Gears
Shaft components
Petrochemical industry
Automotive industry
Energy equipment
