Steel

Minimum yield 235–300 MPa. Ordinary carbon steel, easy to weld, cut and form — and its counterparts in other countries.

Grade	Standard	Yield strength at 10 mm	Tensile strength	Closest to	Evidence
SS400 Japan's general structural steel: 245 MPa yield up to 16 mm, 400–510 MPa tensile. Not intended for welded primary structures.	JIS G 3101	≥ 245 MPa2	400–510 MPa2	S235Approximate	Corroborated 2 Single source 3 Disagreements explained 1

S355 and every grade the world lists against it, compared on what each standard guarantees. Some “equivalents” fall short; their yield shows it.

Grade	Standard	Yield strength at 10 mm	Tensile strength	Closest to	Evidence
SM520 JIS grade whose guaranteed yield actually matches S355: 365 MPa up to 16 mm.	JIS G 3106	≥ 365 MPa1	520–640 MPa2	S355Close match	Corroborated 1 Single source 2
SM490 Japanese welded-structure steel; the 490 is minimum tensile strength, yield is 325 MPa.	JIS G 3106	≥ 325 MPa2	490–610 MPa3	S355Not equivalent	Confirmed 1 Corroborated 1 Single source 1 Disagreements explained 1

Galvanized and metallic-coated sheet, usually 0.4–3 mm, roll-formed into purlins, rails, studs, decking and cladding. Designed to EN 1993-1-3, AISI S100 or AS/NZS 4600. The full-hard grades (S550GD, G550, SS Grade 80) are strong but have almost no elongation.

Grade	Standard	Yield strength	Tensile strength	Closest to	Evidence
SGC400 Japanese hot-dip galvanized structural sheet: 295 MPa yield, 400 MPa tensile.	JIS G 3302	≥ 295 MPa1	≥ 400 MPa1		Single source 3
SGC490 Japanese hot-dip galvanized structural sheet: 365 MPa yield, 490 MPa tensile.	JIS G 3302	≥ 365 MPa1	≥ 490 MPa1	S350GDApproximate	Single source 3