Stainless sheet: grade and finish are separate choices

Treat 304, 316 and 430 as distinct grade labels

304 and 316 belong to the austenitic family; 430 is ferritic. The 316 family includes molybdenum in its composition. These distinctions do not, by themselves, establish that a sheet meets a design, food-contact, chemical-service or outdoor-exposure requirement.

Keep suffixes such as L when specified, and state the governing product standard. Grade names from different standards may have differing limits or conditions. Check the actual designation and certificate instead of relying on a supplier’s shorthand equivalence.

References: British Stainless Steel Association — 50 grades of stainless steel.

Describe the required surface separately

A market label such as “hairline,” “satin” or “mirror” can leave appearance unresolved. Agree a sample and the acceptance criteria rather than assuming every supplier’s finish will match. Do not infer surface roughness from gloss alone.

References: worldstainless — surface treatment and finish descriptions.

Include finish direction, film and cutting requirements

• Material product standard, exact grade and required delivery condition.
• Thickness × width × length in mm, quantity and agreed dimensional tolerances.
• Finish designation; polished side or sides; grain direction relative to the part drawing.
• Surface acceptance sample or roughness requirement when specified by the design.
• Protective film type if required, edge condition, cutting allowance and identification after cutting.
• Material certificate requirements and the method of linking the supplied sheet or cut pieces to the documented batch.

Confirm identity and application requirements

A photo, a shiny surface or a simple magnet check is not a material certificate. Ask the supplier to identify the supplied grade and batch. Final selection depends on the environment, fabrication, cleaning and design requirements; this guide explains how to write the enquiry rather than approving an application.