The key to corrosion resistance
Chromium is the cornerstone of rust prevention for stainless steel. It forms an extremely thin but dense chromium oxide passivation film on the surface, isolating corrosive media. The primary function of nickel is to strengthen and stabilize this membrane of life. In harsh environments, such as acidic, alkaline or chloride ion-containing solutions (such as seawater), the passivation film of pure chromium steel may not be stable enough. The addition of nickel can promote the steel to self-repair more rapidly after damage, re-form a protective film, and significantly enhance the material's resistance to pitting corrosion, crevice corrosion and stress corrosion cracking in complex media. It can be said that nickel has elevated the "corrosion resistance line" of stainless steel from the basic to the advanced level.
To enhance toughness and ductility
Ferritic or martensitic stainless steel without nickel may have high strength, but it is often brittle, especially at low temperatures. The addition of nickel is like injecting a "softener" into the crystal structure of steel. It enables steel to maintain its strength while acquiring excellent toughness (the ability to resist crack propagation) and ductility (the ability to be plastically processed). This means that nickel-containing stainless steel (such as the common 304 type) can be more easily rolled into thin plates, deeply drawn into water tanks, drawn into pipes, or shaped into complex curved surfaces in buildings. In addition, nickel contributes to the characteristic, slightly off-white silvery luster of stainless steel, making its appearance more elegant and pleasing to the eye.
"Stabilizer" of austenitic structure
This is the most crucial metallurgical role of nickel in stainless steel. The microstructure of stainless steel mainly includes austenite, ferrite, martensite, etc. Among them, the austenite structure (with a face-centered cubic crystal structure) endows the material with non-magnetism, high toughness, excellent weldability and work hardening ability. Nickel is precisely a powerful element in the formation of austenite. In chromium-nickel stainless steels (such as 304 containing 8% nickel and 316 containing 10-12% nickel), an adequate amount of nickel ensures that the microstructure of the steel remains completely stable as austenite even at room temperature or low temperatures.
Optimize the processing performance of stainless steel
The benefits of nickel run through the entire manufacturing process. During welding, nickel-containing austenitic stainless steel is less likely to form a hard and brittle martensitic structure in the heat-affected zone of the weld seam, thereby achieving better performance of the welded joint and more uniform corrosion resistance in the weld area. During the heat treatment process, nickel-containing steel is less sensitive to heat treatment and its performance is easier to control.
Post time: Dec-02-2025
