Stainless steel code 201 refers to a specific grade within the 200 series of austenitic stainless steels. This series was developed as a lower-cost alternative to the more traditional 300 series (like 304 and 316), primarily by reducing the amount of nickel, which is a relatively expensive alloying element.
Key characteristics of Type 201 stainless steel include:
- Composition: It's an alloy of iron, chromium, nickel, manganese, and nitrogen. Compared to Type 304 (typically 18% Cr, 8% Ni), Type 201 has a similar chromium content (around 16-18%) but significantly lower nickel (around 3.5-5.5%). To compensate for the reduced nickel and maintain the austenitic structure, higher levels of manganese (around 5.5-7.5%) and nitrogen (up to 0.25%) are added.
- Corrosion Resistance: Type 201 offers moderate corrosion resistance, suitable for many general-purpose applications, especially indoors or in environments without significant exposure to corrosive agents like chlorides or acids. However, its resistance is notably lower than that of Type 304 stainless steel. It is more prone to pitting and crevice corrosion in aggressive environments.
- Mechanical Properties: Due to the nitrogen addition, 201 stainless steel typically has a higher yield strength and work-hardening rate than 304 in the annealed condition. It maintains good ductility and toughness, similar to other austenitic grades.
- Formability and Weldability: It possesses good formability, allowing it to be bent, stamped, and drawn, although its higher work-hardening rate might require more powerful equipment or different tooling setups compared to 304 for severe forming operations. It is readily weldable by common fusion and resistance methods, similar to 304.
- Cost: Its lower nickel content makes Grade 201 significantly less expensive than grades in the 300 series.
- Applications: Commonly used in cost-sensitive applications where the extreme corrosion resistance of 304 or 316 is not necessary. Examples include kitchen appliances (sinks, cookware), restaurant equipment, food service items, automotive trim, window channels, hose clamps, and structural components for transportation (like railway cars).
In summary, stainless steel code 201 identifies an austenitic grade optimized for lower cost by substituting manganese and nitrogen for nickel, offering good strength and formability but with reduced corrosion resistance compared to Type 304.