4140 alloy structural steel, a medium hardenability steel, good strength and good comprehensive mechanical properties after heat treatment, good manufacturability, high yield. The maximum operating temperature is 427℃. Can be used as turbine fastener. Chemical composition:

Carbon C :0.33~0.48

Silicon Si:0.15~0.35

Manganese Mn:0.75 to 1.00

Sulfur S :≤0.030

P :≤0.030

Chromium :0.80~1.10

Molybdenum Mo:0.15~0.25