SUS630 is a martensitic precipitation-hardening stainless steel under the Japanese JIS standard, corresponding to 17-4PH (US) and 05Cr17Ni4Cu4Nb (China). It offers a balance of high strength and moderate corrosion resistance through heat treatment.
Core material properties:
* Chemical composition: 15–17.5% chromium, 3–5% nickel, 3–5% copper, 0.15–0.45% niobium, and carbon ≤0.07%. Copper and niobium enable precipitation hardening and strength control.
* Microstructure: Martensitic at room temperature; solution treatment forms a supersaturated solid solution, and aging precipitates fine copper-rich phases to enhance performance.
* Key performance: After aging, tensile strength 1000–1400 MPa, hardness 30–45 HRC, resistant to atmospheric, freshwater, and neutral salt corrosion, with moderate plasticity and toughness. Stable performance at room and low temperatures (-50°C).
* Other properties: Magnetic, good weldability (post-weld aging required), excellent machinability in solution-treated state, surface properties can be improved by polishing and passivation.
Typical applications:
* Mechanical manufacturing: High-strength bolts, gears, shafts, steam turbine components.
* Aerospace: Aircraft landing gear parts, engine components requiring high strength.
* Petrochemical: High-pressure valves, flanges, pump bodies requiring corrosion resistance and load-bearing capacity.
* Medical devices: Surgical instruments, certain implants requiring biocompatibility.
* Other fields: Injection molds, high-strength structural components in marine environments.