Steel materials & grades

An overview of the steels used in Australian construction and fabrication: what each is called, which Standard covers it, and what it is used for. The section (e.g. 310UB40.4) describes the shape; the grade describes the steel it is made from.

Structural carbon steel

Product	Typical grades	Standard	Min. yield (MPa)	Typical uses	Notes
Hot-rolled sections & bar	300 (300PLUS), 350	AS/NZS 3679.1	280–360	Universal beams and columns, channels, angles, flats, rounds	Yield reduces with thickness. See steel grades.
Structural plate	250, 300, 350, 400, 450	AS/NZS 3678	230–450	Welded beams and columns, base plates, gussets, stiffeners	L0/L15/L20 suffixes indicate impact-tested grades.
Hot-rolled coil, sheet & floorplate	HA200–HA400, HW350, XF300–XF500	AS/NZS 1594	200–480	Folded plates, chequer floorplate, light fabrications	Commercial grades (HA1, HA3) have no guaranteed yield.
Cold-formed hollow sections	C250L0, C350L0, C450L0	AS/NZS 1163	250–450	CHS, SHS and RHS columns, trusses, frames	Supplied clear, pre-galvanised (in-line) or hot-dip galvanised.
Metallic-coated sheet & strip	G250, G300, G450, G500, G550	AS 1397	250–550	Purlins, girts, roofing, light-gauge framing	Coating classes such as Z275, Z350, Z450 and AZ150 (zinc/aluminium).

Weathering steel

Product	Typical grades	Standard	Min. yield (MPa)	Typical uses	Notes
Weathering plate & sheet	WR350, REDCOR	AS/NZS 3678, AS/NZS 1594	340	Exposed architectural and bridge steelwork, landscaping	Forms a protective patina. Not for marine, wet or crevice-prone details.

High-strength plate

Product	Typical grades	Standard	Min. yield (MPa)	Typical uses	Notes
Quenched & tempered plate	Grade 500, 600, 700 (e.g. Bisplate 60/70/80)	AS 3597	500–690	Cranes, mining equipment, heavy transport, lightweight high-load structures	Needs controlled welding procedures (preheat, low-hydrogen).

Wear-resistant plate

Product	Typical grades	Standard	Min. yield (MPa)	Typical uses	Notes
Abrasion-resistant plate	400, 450, 500 HB (e.g. Bisalloy 400, Hardox 450)	Manufacturer specification	–	Chutes, liners, buckets, truck bodies	Specified by hardness, not yield. Generally not used as structural steel.

Reinforcing steel

Product	Typical grades	Standard	Min. yield (MPa)	Typical uses	Notes
Reinforcing bar & mesh	D500N, D500L, R250N	AS/NZS 4671	250–500	Concrete reinforcement, mesh, ligatures	N = normal ductility, L = low ductility (mesh), R = round bar.

Fasteners

Product	Typical grades	Standard	Min. yield (MPa)	Typical uses	Notes
Structural bolts	Property class 4.6, 8.8, 10.9	AS 1111, AS 1110, AS/NZS 1252.1	240 / 660 / 940 (fu 400 / 830 / 1040)	Bolted connections (4.6/S, 8.8/S, 8.8/TB, 8.8/TF and the 10.9 categories)	TB and TF bolts are fully tensioned; TF are friction-type. Grade 8.8 below M16: fu 800. 10.9 was added in AS 4100:2020.

Stainless steel

Product	Typical grades	Standard	Min. yield (MPa)	Typical uses	Notes
Austenitic stainless	304/304L, 316/316L	ASTM A240, AS/NZS 4673	≈ 170–205 (0.2% proof)	Handrails, balustrades, food and marine environments	316 has molybdenum for better pitting resistance. Avoid contact with carbon steel.
Duplex stainless	2205 (1.4462)	ASTM A240, AS/NZS 4673	≈ 450 (0.2% proof)	Marine, chemical and high-strength stainless structures	About twice the proof stress of 304/316.

Engineering steel

Product	Typical grades	Standard	Min. yield (MPa)	Typical uses	Notes
Carbon & alloy bar	1020, 1045, 4140, 4340	AS 1442, AS 1444	Depends on condition	Pins, shafts, bushes, machined parts	Properties depend strongly on heat treatment and size; check the supplier certificate.

Values are indicative minimums. Yield strength usually reduces with thickness. Always specify the grade and Standard on drawings and check mill certificates. Detailed yield/tensile tables for structural grades are on the steel grades page.