AISI 431
Martensitic
AISI 431 stainless steel is a high-strength, martensitic stainless steel known for its excellent corrosion resistance and good mechanical properties. With a composition of around 15-17% chromium and 1.25-2.5% nickel, it offers superior resistance to corrosion, especially in marine environments, compared to other martensitic steels. AISI 431 is highly resistant to both stress corrosion cracking and high-strength applications, making it ideal for shafts, bolts, and fasteners. It can be heat-treated to achieve high tensile strength and hardness while maintaining good toughness. However, it has lower weldability and formability than austenitic grades like 304 or 316.
