It mainly consists of carbon (C: 0.17-0.25), silicon (Si: 0.15-0.35), manganese (Mn: 0.35-0.85), chromium (Cr: 1.20-1.50), molybdenum (Mo: 0.65-0.80), and vanadium (V: 0.25-0.35) and other elements. The reasonable proportion of these elements gives the steel excellent comprehensive properties.

In the heat-treated state, 1.7709 steel has high strength and good mechanical properties. Its yield strength (Rp0.2) can reach ≥550 MPa, tensile strength (PM) can reach ≥700 MPa, elongation (A) ≥16%, and reduction of area (A) ≥60%.

This material can still maintain good mechanical properties in high-temperature environments and is suitable for working conditions with temperatures exceeding 300°C.

Aerospace engine: The turbine blade fasteners are manufactured using nickel-based high-temperature alloys (such as GH4049), maintaining a tensile strength of ≥ 1000 MPa at 600 - 900℃, and achieving complex shape processing through die forging technology.

Spacecraft structure: Components used for connecting the combustion chamber of the rocket engine, must withstand instantaneous high temperatures (>1200℃) and vibration loads.

Nuclear power plant: The bolts of the reactor pressure vessel must meet a lasting strength of ≥ 95 MPa (at 700°C/100,000 hours), to prevent hydrogen embrittlement and stress corrosion cracking.

Gas turbine: High-temperature bolts (such as A286 alloy) are used to fix the turbine discs and must undergo creep limit tests (1% total deformation/1000 hours)

Refining and processing unit: The bolts of the hydrogenation reactor need to be used for a long time under high temperature and high pressure (400℃/20MPa), and the material must pass the hydrogen-induced delayed fracture test.

Mold manufacturing: The fastening components of composite material molds need to match a low thermal expansion coefficient (CTE ≤ 10⁻⁶/℃) to maintain dimensional stability.

New energy vehicles: The motor shaft bolts are made of titanium alloy (such as TC4), with a tensile strength of up to 900 MPa and no magnetic interference. The tapping process needs to be optimized to reduce work hardening.