Stainless Steel Grades: A Buyer’s Guide

When buying stainless steel for your project, the grade you choose determines strength, corrosion resistance, weldability and cost. Understanding the basics will help you specify the right material and avoid expensive mistakes.

Austenitic (300 series) — the most popular family, led by 304 and 316. They are non-magnetic, highly corrosion-resistant and easy to form and weld. 316 adds molybdenum for superior resistance to chlorides and salt water, making it ideal for marine, food and chemical environments.

Ferritic (400 series) — magnetic and lower in nickel, offering good corrosion resistance at a more economical price. They are a smart choice where moderate resistance and flatness are the priority.

Martensitic — hardenable, magnetic and stronger, used for knives, shafts and wear components.

Duplex — roughly double the strength of standard austenitic grades with excellent stress-corrosion resistance, favored in offshore and petrochemical applications.

Buyer tip: always match the grade to the actual service environment — chloride exposure, temperature and fabrication method. Your supplier should help you confirm the right grade, dimensions and quantity before quoting.