Steel plates can be classified in various ways based on different properties and applications. The following are some common classifications:
Thin plate: Generally refers to steel plates with a small thickness.
Medium plate: Steel plates with a medium thickness.
Thick plate: Steel plates with a relatively large thickness.
Extra-thick plate: Steel plates with an extremely large thickness.
Galvanized plate: Surface coated with zinc to enhance corrosion resistance, including hot-dip galvanized plates and electrogalvanized plates.
Tin-plated plate: Surface coated with tin, commonly used for food packaging such as cans.
Clad steel plate: Has a multi-layer structure for specific applications.
Color-coated steel plate: Surface coated with colored paint, used in construction and decoration.
GB/T 709-2019: Dimensions, shape, weight, and permissible deviations of hot-rolled steel plates and strips (general technical standard).
GB/T 3274-2017: Hot-rolled thick steel plates and strips of carbon structural steel and low-alloy structural steel (product and general technical standard).
GB/T 710-2008: Hot-rolled thin steel plates and strips of high-quality carbon structural steel (product standard) – Note: GB/T 710-2008 (abolished) is fully replaced by GB/T 711-2017.
GB/T 711-2017: Hot-rolled steel plates and strips of high-quality carbon structural steel (product standard).
GB/T 11251-2009: Hot-rolled thick alloy steel plates (product standard).
GB/T 4237-2005: Hot-rolled stainless steel plates and strips (product standard).
① Hot-rolled 20# steel plate with thickness 2mm, ordinary drawing grade P, higher-grade finished surface Ⅰ: Marked as: 2-GB/T 709-1988, 20-P-Ⅰ-GB/T 710-1991.② Hot-rolled 20# steel plate with thickness 8mm, class A thickness permissible deviation, edge-trimmed EC, ordinary surface (FA): Marked as: 8-A-GB/T 709-2019, 20-EC-FA-GB/T 711-2017.Note: The two marking examples above differ due to updates to relevant standards for hot-rolled steel plates.
Hot-rolled Q235A steel plate with thickness 5mm, class N thickness permissible deviation, non-edge-trimmed EM: Marked as: 5-N-GB/T 709-2019, Q235A-EM-GB/T 3274-2017.
GB/T 708: Dimensions, shape, weight, and permissible deviations of cold-rolled steel plates and strips (general technical standard).
GB/T 5213-2019: Cold-rolled low-carbon steel plates and strips (product standard).
GB/T 11253-2019: Cold-rolled thin steel plates and strips of carbon structural steel.
GB/T 13237-2013: Cold-rolled steel plates and strips of high-quality carbon structural steel (product standard).
GB/T 3280-2015: Cold-rolled stainless steel plates and strips (product standard).
① Grade 20, size 1.0×1000×1500, surface quality group Ⅱ, drawing grade S (per GB 708-1988 and GB 710-88): Marked as: Cold-rolled Steel Plate 1.0×1000×1500-GB 708-88, 20-Ⅱ-S-GB 710-88.Note: Marking example for cold-rolled steel plates in GB 708-1988; GB 710-88 refers to high-quality carbon structural steel.② Grade 20, size 1.0×1000×1500, dimensional accuracy grade A, surface quality grade FB, edge-trimmed EC: Marked as: Cold-rolled Steel Plate A-1.0×1000×1500-GB/T 708-2019, 20-FB-EC-GB/T 13237-2013.Note: GB/T 708-2006 replaces GB 708-88; GB/T 13237-2013 replaces GB 710-88.
GB/T 15675: Continuously electrogalvanized and zinc-nickel alloy coated steel plates and strips (technical standard).
GB/T 2518: Continuously hot-dip galvanized steel plates and strips (technical standard).
GB/T 5213-2019: Cold-rolled low-carbon steel plates and strips (product standard).
GB/T 1567-2020: Steel plates and strips may use products from GB/T 5213 and GB/T 20564 (all parts) as base materials.
Example 1: Grade DX1 (D-electroplated, X-zinc, 1-commercial grade), size 2 (thickness) ×1000 (width) ×2500 (length), equal zinc coating 42/42, rolling accuracy B, surface chromate treatment C: Marked as: DX1-2×1000×2500-42/42-B-C-GB/T 15675-1995.Example 2: Grade DC01+ZN (DC01-base material grade for general use, D-cold forming steel plate/strip, 01-sequential number per GB/T 5213-2019; ZN-zinc coating), size 2 (thickness) ×1000 (width) ×2500 (length), equal zinc coating 42/42, surface quality grade FA, surface treatment C, dimensional accuracy A: Marked as: DC01+ZN-2×1000×2500-42/42-FA-C-A-GB/T 15675-2020.
Marking sequence (per GB/T 2518-2004): Standard number - Performance grade - Coating type - Zinc coating weight - Surface structure - Surface treatment - Steel base type - Specification size.Example 1: Hot-dip galvanized steel plate, mechanical interlock grade 02, zinc coating weight 275g/m² (Z275), normal spangle skin-passed (NS), surface treatment passivated + oiled (CO), surface quality grade FB, cold-rolled base material, size 2.0mm×1200mm×2000mm: Marked as: GB/T 2518-02Z275-NS-CO-FB-2.0×1200×2000.Example 2 (per GB/T 2518-2019): Low-carbon steel plate DX51D+AZ (DX-D for cold forming flat steel, X-no specified base material rolling state; AZ-aluminum-zinc alloy coating), coating weight 180g/m² (total for double sides) or 90/90g/m² (per side), normal spangle (N), surface treatment fingerprint-resistant film (AF), surface quality FC, size 0.5mm×1200mm×2000mm:
Total double-sided coating weight marking: GB/T 2518-DX51D+AZ180-N-AF-FC-0.5×1200×2000.
Single-sided coating weight marking: GB/T 2518-DX51D+AZ90/90-N-AF-FC-0.5×1200×2000.
Note: Replacing X with C indicates the base material is specified as cold-rolled; replacing with D indicates hot-rolled.
Example 1: Single cold-reduced tin-plated plate P (per this standard), steel grade TH61+SE (single cold-reduced tin-plated plate), steel base MR class, box annealing (BA), stone surface (St), equal coating 8.4g/m² (2.8/2.8g/m² per side), thickness 0.22mm, width 800mm, length 900mm: Marked as: P-GB/T 2520-TH61+SE-2.8/2.8-0.22×800×900-MR-BA-St.Example 2: Double cold-reduced tin-plated coil C (per this standard), steel grade T620+SE (double cold-reduced tin-plated plate), steel base MR class, continuous annealing (CA), tin coating 8.4g/m² on one side and 5.6g/m² on the other, thickness 0.18mm, width 750mm: Marked as: C-GB/T 2520-TH620+SE-D8.4/5.6-0.18×750-MR-CA.
