Metals & steel
Aluminium alloy series and temper designation 6063-T5 / 5083-H111
Wrought aluminium alloys follow a four-digit system: 1xxx pure aluminium (foil, conductors), 3xxx manganese (cans, roofing), 5xxx magnesium and seawater-resistant (ships, tanks), 6xxx magnesium-silicon (extrusions, 6063/6061), 7xxx zinc and high strength (aerospace, 7075). The temper code after a dash gives the condition: O annealed, H strain-hardened (H14, H24), T heat-treated (T5 artificially aged, T6 solution-treated and artificially aged). Primary ingot is priced at LME plus a regional premium, and semi-finished products add a conversion premium on top.
Coating weight (Z100, Z275, AZ150)
For galvanised and Galvalume sheet it shows the total coating on both surfaces in g/m² (EN 10346): Z275 means 275 g/m² of zinc on both sides together, roughly 20 µm per side. Coating weight directly determines corrosion life: Z100–Z140 is typical for indoor and appliance use, Z200–Z275 or AZ150 for roofing, cladding and outdoor use. Price rises with coating weight, so it must always be stated in offers and verified on the certificate.
Copper cathode Grade A (LME) Cu-CATH-1
Copper sheets produced by electrolytic refining with at least 99.99 % purity (BS EN 1978 Cu-CATH-1 or ASTM B115 Grade 1) from LME-registered brands; the main feedstock for wire rod, tube and alloy production. Non-registered or off-spec cathodes trade at a discount and registered Grade A at a premium; shipments are checked for brand, weight band, bundle count and quality certificate. Cathode is usually priced at the LME average of the shipment or arrival month plus a Shanghai, Rotterdam or US regional premium.
Flat steel: hot-rolled (HRC), cold-rolled (CRC) and galvanised (HDG)
HRC is made by rolling slab at around 1,100 °C to 1.2–25 mm; its surface carries scale, and it is used for pipe, sections, ships and structures and is the main benchmark of global steel prices. Pickling HRC and reducing it at room temperature to 0.2–3 mm gives CRC, with a smoother surface and tighter tolerances for appliances and automotive. Hot-dip zinc coating of CRC gives galvanised sheet (GI, DX51D+Z), aluminium-zinc gives Galvalume (AZ), and painting gives pre-painted steel (PPGI).
Scrap classification (ISRI, HMS 1&2, shredded, Millberry)
International scrap grades are defined by code names in the ISRI (now ReMA) Scrap Specifications Circular. In ferrous scrap, HMS 1 is at least 6 mm thick while HMS 2 includes thinner and galvanised pieces, and “80:20” gives the blend ratio; shredded scrap (ISRI 210/211) is fragmented and magnetically separated, dense material, while P&S and busheling (new production cuttings) are cleaner. Non-ferrous grades use codes such as Barley/Millberry (99.9 % bright copper wire), Berry/Candy, Honey (yellow brass) and Taint/Tabor (mixed aluminium). Radioactivity, sealed containers, dirt and foreign matter should be capped in the contract.
Stainless steel grades (304, 316, 430, duplex)
Steels containing at least 10.5 % chromium, which forms a protective chromium-oxide film. 304 (1.4301, 18 % Cr – 8 % Ni) is austenitic, general-purpose and food-safe; 316/316L (1.4401/1.4404) adds 2–3 % molybdenum for better resistance to chlorides, seawater and chemical plants; 430 (1.4016) is a nickel-free, magnetic and cheaper ferritic grade; the 201/202 series replaces nickel with manganese. Duplex (2205) offers high strength and stress-corrosion resistance. Stainless prices move with an alloy surcharge linked to nickel and molybdenum prices.
Steel grade designation (EN, ASTM, AISI, JIS, GB)
Steels carry different names in different standard systems. In the European system (EN 10027) a letter shows the use and a number the minimum yield strength: S235JR is a structural steel with 235 MPa and impact tested at 20 °C, while S355J2 is tested at –20 °C. Approximate equivalents are ASTM A36 or A572 Gr.50, JIS SS400 in Japan and GB Q235/Q355 in China; for stainless, AISI 304 ≈ EN 1.4301. Equivalents are not identical, so chemistry and mechanical values should be checked on the certificate.
Yield strength, tensile strength and elongation
The basic mechanical properties measured in a tensile test (EN ISO 6892-1, ASTM E8). Yield strength (ReH or Rp0.2, MPa) is the stress at which the material starts to deform permanently and is the basis of design; tensile strength (Rm) is the maximum stress before fracture; elongation (A %) is the stretch up to fracture and indicates formability. For rebar the Rm/ReH ratio and elongation are critical for earthquake resistance (e.g. Rm/Re ≥ 1.15 for B500C).