Galvanized Steel coil sheet is a pure zinc coating applied to the surface of a carbon steel sheet, which is available in a wide variety of choices, and therefore there are many types of galvanized steel. There are five grades of galvanized steel: commercial, structural, deep-drawn, ultra-deep-drawn, and high-strength structural, depending on the design strength, forming process, and corrosion protection requirements.
Commercial Grade (CS)
Structural Quality galvanized steel is a common basic galvanized steel sheet that meets general industrial and construction needs without special mechanical properties or formability requirements.
Representative grades: ASTM A653 CS Type A/B, EN 10346 DX51D+Z/DX51D+ZM, GB/T 2518 CR1 CR2
Core properties: basic rustproofing + general strength
Typical applications: light duty structures: distribution boxes, pipelines, steel structures, storage racks, non-load-bearing enclosures, agricultural equipment, etc.
Chemical composition: low carbon (C≤0.10%), no special alloy requirements
Mechanical properties:
- Tensile strength: 270-410 MPa
- Elongation (A50): ≥20%
- Processing requirements: only support simple bending (prohibit deep stamping)
Structural Grade（SS）
Structural Grade galvanized steel is a one-week, high-strength galvanized steel designed for structural load-bearing applications that require specific mechanical properties (e.g., tensile strength, yield strength).
Representative grades: ASTM A653 SS Grade 33/40, EN 10346 S280GD+Z/S320GD+ZA, GB/T 2518 CR390LA
Core Properties: High Strength + Weldability
Typical Applications: Building frames (steel beams, roof trusses), bridges, towers, load-bearing structures of industrial plants, heavy equipment brackets, building frames, vehicle chassis, Container skeleton, etc.
Chemical composition: add micro-alloy (Nb/V/Ti), control carbon equivalent (Ceq≤0.25%)
Mechanical properties:
- Tensile strength: 340-550 MPa
- Yield strength: ≥ 230 MPa
- Processing requirements: need to be adapted to the welding process (low preheat temperature)
Drawing Grade (D)
Drawing quality galvanized steel has good ductility and is suitable for medium-complexity stamping and forming processes.
Representative grades: ASTM A653 DDS Type C, EN 10346 DC04+ZE/DC05+ZF, GB/T 2518 CR3/CR4
Core properties: High ductility (uniform deformation capacity)
Typical applications: Complex stamped parts (electrical appliance housings, fuel tanks), household appliance liners (e.g., washing machine drums), architectural decorative parts, lamp housings, deep-drawn cans, automotive coverings etc. .
Chemical composition: ultra-low carbon (C ≤ 0.08%), low sulfur (S ≤ 0.025%)
Mechanical properties:
- Elongation (A50): ≥ 30%
- Plasticity-strain ratio (r value): ≥ 1.4
- Processing requirements: need to be multi-channel progressive stamping molding
Extra Deep Drawing Grade（EDD / EDDS）
Extra Deep Drawing quality galvanized steel has top forming properties and is suitable for extremely complex stamping process processing with multiple drawing passes.
Representative grades: ASTM A653 EDD/70/EDDS, EN 10346 DC06+Z/DC07+ZM, GB/T 2518 CR5/CR180IF
Core properties: Extreme formability (resistance to localized thinning)
Typical applications: automotive cladding (doors, hoods), complex shaped parts, housings of high end home appliances, precision instruments, etc.
Key technologies:
- IF steel (gapless atomic steel)
- Grain size ≥ 7 (ASTM standard)
Mechanical properties:
- Elongation (A80): ≥ 40%
- Strain-hardening index (n-value): ≥ 0.22
- Processing requirements: requires precision molds (surface lubrication treatment)
High Strength Structural Grade（ HSS）
High Strength Structural quality Galvanized Steel, through the addition of manganese, boron, niobium and other elements or the use of hot/cold rolling tempering process to ensure structural strength at the same time, through alloying or heat treatment to enhance the mechanical properties.
Representative grades: ASTM A653 HSLAS Grade 55/70/DH600, EN 10346 HCT600X+Z/HX420LAD+ZM, GB/T 2518 CR340/590DP/CR550/980TRIP.
Core properties: optimized strength-to-weight ratio
Typical applications: lightweight car bodies (B-pillars, crash beams), mining vehicle chassis, high-rise building seismic structures, crane booms, large-span bridges, offshore platforms, photovoltaic mounts, etc.
Strengthening mechanism:
- DP (Duplex steel): ferrite+martensite
- HSLA (Low-alloyed high-strength steel): precipitation strengthening
Mechanical properties:
- Tensile strength: 550- 980 MPa
- Yield ratio: ≤ 0.85 (high energy absorption)
- Processing requirements: laser cutting/hydraulic molding (to avoid rebound defects)
Key Comparison Summary
| Grade | Strength Level | Formability | Core Advantage | Applicable Process |
| Commercial Grade (CS) | ★☆☆☆☆ | ★★☆☆☆ | Low cost | Simple cutting/bending |
| Structural Grade (SS) | ★★★☆☆ | ★★☆☆☆ | Welding stability | Welding/bolt connections |
| Deep Drawing Grade (D) | ★★☆☆☆ | ★★★★☆ | Uniform elongation | Multi-step stamping |
| Extra Deep Drawing Grade (EDD) | ★☆☆☆☆ | ★★★★★ | Extreme deep drawing ability | Precision stamping |
| High Strength Structural Grade (HSS) | ★★★★★ | ★★☆☆☆ | Lightweight design | Hot forming/hydraulic forming |
Wanzhi Group produces all grades of galvanized steel in accordance with ASTM A653, EN10346, GB/T 2518, and JIS G3302. Different grades of galvanized steel can be matched with zinc coatings ranging from Z20 to Z350 (structural grades are commonly used with thicker coatings of ≥180g/m²).