Aluminum sheet buyers should lock the alloy-temper-thickness combination to the end-use duty before pricing RFQs, because the same nominal 3 mm panel behaves as deep-drawn packaging stock, structural frame plate, or marine-grade tank skin depending on whether the spec reads 1100-O, 3003-H14, 5052-H32, or 6061-T6 [S2][S3].
The four alloy families that cover roughly 90% of industrial sheet purchases are 1xxx (pure Al, ≥99% Al, formable, low strength), 3xxx (Al-Mn, ~1% Mn, work-hardenable, general purpose), 5xxx (Al-Mg, 2.5-5% Mg, weldable, marine/chemical), and 6xxx (Al-Mg-Si with Mg2Si precipitation hardening, structural) [S2][S3]. Choosing wrong wastes 15-40% of material cost and forces downstream rework in welding, anodizing, or forming.
Alloy Family Decision Tree: 1xxx vs 3xxx vs 5xxx vs 6xxx
1xxx series (1050, 1060, 1100) carries ≥99% aluminum and is specified where corrosion resistance and formability matter more than strength — chemical tanks, food packaging, reflectors, transformer windings, and decorative panels — with typical tensile strength around 70-130 MPa in O temper and a density near 2.71 g/cm³ [S3].
3xxx series (3003, 3004, 3105) adds roughly 1% manganese for 20-30% higher strength than 1xxx while keeping excellent formability, which is why 3003 dominates cookware, HVAC ducting, roofing, and signage [S3]. 5xxx series (5052, 5083, 5754) introduces 2-5% magnesium, which cannot be heat-treated but work-hardens to welded-structural strength — 5052-H32 sheet at 3 mm routinely reaches 230 MPa tensile with elongation above 10% and is the default for marine hulls, vehicle panels, and pressure vessels [S3]. 6xxx series (6061 is the workhorse) uses Mg2Si precipitation hardening for T6 temper properties near 310 MPa tensile and 275 MPa yield at 3 mm plate — the highest strength in the common sheet/plate family and the default for aluminum window and door frames, structural aluminum ladder rails, and transport platforms [S2].
Thickness Bands: Sheet vs Plate Boundary and Stock Forms
Chinese flat-rolled stock convention splits product into sheet (0.15-6.0 mm) and plate (6.0-200 mm), with 0.15-2.0 mm classified as thin sheet, 2.0-6.0 mm as standard sheet, 6.0-25.0 mm as medium plate, 25-200 mm as heavy plate, and over 200 mm as ultra-heavy plate [S3]. This convention tracks closely with ASTM B209 and EN 485-1 plate/sheet boundary at 6.35 mm (0.25 in).
Selection rule: pick thin sheet (≤2 mm) when the part is roll-formed, stamped, or deep-drawn — typical tolerances ±0.05 mm on 1xxx-O packaging stock. Standard sheet (2-6 mm) covers enclosures, aluminum veneer panel skins, and most truck/trailer skins. Medium plate (6-25 mm) is the workhorse for tooling fixtures, aluminum alloy structural frames, and base plates. Heavy plate (25-200 mm) is reserved for shipbuilding, mold tooling, and pressure vessel heads [S3].
Temper Codes: O, H, T and What Each Tells the Buyer
Temper designation follows the unified H/T system: O means annealed (softest, maximum formability, used for 1xxx and 3xxx deep drawing), H denotes strain-hardened (H12, H14, H16, H18 step up in strength; H32, H34 add a low-temperature stabilization for 5xxx series to prevent age softening), and T means thermally treated (T4 solution heat-treated + naturally aged; T6 solution + artificial aging for peak strength in 6xxx) [S2][S3].
Buyer-side rule of thumb: 5052-H32 vs 5052-H34 differs by roughly 15-25 MPa in yield strength, so if your weld fixture is right at the deflection limit, step up one H-tick. For 6061, T6 gives roughly 60% higher yield than T4, but T4 is required when the part must be formed after quenching — 6061-T6 sheet cannot be bent sharply without cracking. Embossed/patterned sheet (花纹板) usually ships as 1060/3003/5052 in H14 or H24 temper, thickness 1.0-6.0 mm, with raised diamond or 5-bar pattern for slip resistance [S3].
Application-to-Alloy Mapping: 12 Common Sheet Uses
Standardized application-alloy pairings from public mill literature: (1) lighting reflectors → 1060/1070-O, polished; (2) solar reflector backs → 3003-H16; (3) building curtain wall / aluminum veneer panel → 3003/3004-H14 fluorocarbon-coated; (4) interior ceilings → 1100/3003-O; (5) furniture and cabinet skin → 3003-H14; (6) elevator panels → 5052-H32; (7) nameplates and signs → 1100-O anodized; (8) automotive interior/exterior → 5052/5182-O for formed panels, 6016/6111-T4 for body-in-white; (9) photo frames → 1070-O; (10) refrigerator and appliance casings → 3003/3105-H14; (11) aerospace — 2024-T3, 7075-T6, 7050-T7451 for primary structure, 2xxx/7xxx outside the standard 1/3/5/6xxx envelope; (12) railway vehicle and high-speed train bodies → 5083-H32 and 6xxx-T6 for crash-energy-absorbing extrusions mated with sheet [S3].
Specifying 6061-T6 where 5052-H32 would work is the most common over-spec — buyer pays ~25% premium for machinability the part does not need [S2].
Comparison Table: Alloy-Temper-Property Quick-Reference
Four common options on four buyer-critical criteria (values are typical, not guaranteed, and should be confirmed against mill certificate before PO):
1100-O (1xxx, annealed): density 2.71 g/cm³, tensile 70-105 MPa, formability excellent, weldability excellent, corrosion resistance excellent, typical use chemical tanks and reflectors. 3003-H14 (3xxx, work-hardened): density 2.73 g/cm³, tensile 145-180 MPa, formability very good, weldability good, corrosion resistance very good, typical use cookware and roofing. 5052-H32 (5xxx, strain-hardened + stabilized): density 2.68 g/cm³, tensile 215-260 MPa, formability good, weldability excellent, corrosion resistance excellent in marine atmosphere, typical use marine panels and pressure vessels. 6061-T6 (6xxx, precipitation-hardened): density 2.70 g/cm³, tensile 290-340 MPa, formability fair (must be formed in T4), weldability good (welded region loses T6 strength), corrosion resistance good, typical use structural frames, ladders, and transport platforms [S2][S3].
When NOT to Choose the Mainstream Option
Do not specify 6061-T6 sheet for welded pressure vessels: the HAZ reverts to T4 strength (drop of 30-40%) and the inspector will reject ASME BPVC Section VIII weld procedure qualification if you claim 6061-T6 across the weld. Use 5083-H321 or 5052-H32 instead [S3].
Do not specify 1100-O for any structural bracket or load-bearing aluminum ladder rail — yield near 35 MPa is below the safety margin for any human-bearing application; switch to 6061-T6 or 5083-H111 plate. Do not specify 3003 for marine splash zones; Mn does not protect against galvanic corrosion next to stainless fasteners — use 5052 or 5083. For extrusion-skin sandwich panels, where the sheet is bonded to an extruded core, see the Aluminum Extrusion Profile Types: Alloy, Temper, and Application Map for the matching temper pairing.
Procurement and Inspection Signals to Track
Three pre-shipment checks separate a clean PO from a field failure: (1) mill certificate must list actual chemistry (especially Mg in 5xxx and Mg+Si in 6xxx) and actual tensile/yield/elongation, not just "meets standard"; (2) thickness tolerance per EN 485-4 (for 3 mm 5052-H32, typical ±0.10 mm for width ≤1500 mm) must be written into the PO, not assumed; (3) for anodizing or PVDF coil-coated stock, confirm surface pretreatment grade (AAMA 2603/2604/2605 for architectural aluminum veneer panel — 2605 is the 30-year fluorocarbon top coat). For tooling-grade plate (6061-T651, 7075-T7351), check ultrasonic per ASTM B594 if the part is aerospace [S3].
Two trackable signals for 2026 sourcing: (a) Chinese mill capacity continues to dominate 1xxx/3xxx/5xxx commodity sheet at 1-6 mm — expect 4-8 week lead time for in-stock H32/H14 and 10-14 weeks for T6 plate above 25 mm; (b) European and North American mills hold the technical edge on 2024/7075 aerospace plate and on 5754/5083 H116/H321 marine plate with DNV/CCS/BV classification society certificates — request the certificate at RFQ, not after delivery. For buyers evaluating roll-formed profiles downstream of sheet stock, the Aluminum Extrusion Profile vs Die Casting Machine: Spec Decision Map covers when to switch from sheet fabrication to extruded or die-cast part geometry.