What are the common materials used for stainless steel bolts?

2025-06-05 14:57:38

1. Austenitic Stainless Steel

A2 (ISO) / AISI 304
Characteristics: Good corrosion resistance, formability, and weldability. Non-magnetic (may become slightly magnetic after cold working).
Applications: Food processing, construction, general industrial environments.

A4 (ISO) / AISI 316
Characteristics: Contains 2–3% molybdenum for enhanced resistance to chloride corrosion; suitable for marine environments.
Applications: Marine hardware, chemical equipment, coastal structures.

AISI 316L
Low-Carbon Version: Reduced risk of chromium carbide precipitation after welding, improved intergranular corrosion resistance.
Applications: Surgical instruments, medical implants.

AISI 321 / 347
Stabilized Grades (with Ti/Nb): Resistant to high-temperature oxidation (below 800°C), prevents intergranular corrosion.
Applications: Aircraft engines, high-temperature piping.

904L (UNS N08904)
High-Alloy Stainless Steel: Excellent resistance to strong acids and seawater corrosion; higher cost.
Applications: Chemical reactors, desalination systems.

254 SMO (UNS S31254)
Super Austenitic Stainless Steel: High molybdenum (6%) and nitrogen content; outstanding pitting resistance; an alternative to titanium alloys.
Applications: Seawater treatment, flue gas desulfurization systems.

2. Martensitic Stainless Steel

AISI 410 / 416
Characteristics: Hardenable by heat treatment, offers high hardness but lower corrosion resistance. Grade 416 has added sulfur for improved machinability.
Applications: General mechanical parts, valves (in non-corrosive environments).

3. Duplex Stainless Steel

2205 (UNS S31803 / S32205)
Characteristics: Dual-phase structure (austenite + ferrite), high strength, good resistance to stress corrosion cracking.
Applications: Oil pipelines, chemical storage tanks.

2507 (UNS S32750)
Super Duplex: Higher alloy content for superior resistance to chloride-induced corrosion.
Applications: Deep-sea equipment, highly chlorinated environments.

4. Precipitation-Hardening Stainless Steel

17-4PH (AISI 630)
Characteristics: Achieves high strength through aging treatment (tensile strength up to 1300 MPa) while maintaining corrosion resistance.
Applications: Aerospace fasteners, nuclear industry.