Chemical Composition: According to GB/T 699 - 2015 standard, the carbon content is 0.52% - 0.60%, silicon 0.17% - 0.37%, manganese 0.50% - 0.80%, sulfur ≤0.035%, phosphorus ≤0.035%, chromium ≤0.25%, nickel ≤0.30%, and copper ≤0.25%.
Mechanical Properties: The tensile strength is ≥645MPa, the yield strength is ≥380MPa, the elongation is ≥13%, the reduction of area is ≥35%, the hardness of the un - heat - treated steel is ≤255HB, and the hardness of the annealed steel is ≤217HB.
Processing Properties: The cutting - processing performance is medium. Due to the relatively high carbon content, the hardness increases after quenching, which brings certain difficulties to cutting. Its weldability and hardenability are poor, and there is a tendency to form cracks during water quenching, so the process parameters need to be strictly controlled during welding and heat treatment.
Typical Applications: It is often used to manufacture parts that require higher strength and wear resistance, as well as parts with low elastic, dynamic load and impact load, such as gears, rim, flat springs, crankshafts, etc. It is also widely used in engineering machinery, automotive parts, tools and blades, forgings and other fields.