Understanding Steel Grades: A Buyer's Guide
01What a grade code actually tells you
A steel grade specifies chemical composition and mechanical properties — yield strength, tensile strength, and often weldability characteristics. S355JR, for example, guarantees a minimum yield strength of 355 MPa under EN 10025-2, plus specific impact toughness requirements.
02Structural mild steel grades
S355JR (European), A36 (American), and Grade 300W (South African) are the most common structural mild steel grades. They're broadly comparable in strength class but differ in exact chemistry and test requirements — your engineer will usually specify one based on the design code the project follows.
03Stainless steel grades
304 stainless is the general-purpose grade for food-grade and architectural work. 316 adds molybdenum for significantly better corrosion resistance in chloride environments — coastal areas, chemical exposure, or wash-down environments — at a higher material cost.
04How to choose without an engineering background
If you're specifying material for a project without a structural engineer involved, tell your fabricator the exposure environment, expected load, and any code requirements (like SANS 10400 for buildings) — a good fabricator will recommend the correct grade rather than defaulting to the cheapest option.
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