JIS G 3302:2018 –Continuously Hot-Dip Zinc-Coated Steel Sheet and Strip

Standard Number: JIS G 3302:2018
Title: Continuously Hot-Dip Zinc-Coated Steel Sheet and Strip
Published by: Japanese Industrial Standards Committee (JISC)
Equivalent International References: Similar to ASTM A653, EN 10346, GB/T 2518

Scope

This Japanese Industrial Standard specifies the requirements for continuously hot-dip zinc-coated steel sheet and strip, manufactured from cold-rolled or hot-rolled steel base materials. The product is suitable for applications requiring corrosion resistance, formability, and paint adhesion, such as in construction, automotive, electrical appliances, and general industrial manufacturing.

✅ Applies to both coil and cut-to-length sheets.

Steel Grades (Classification by Use and Strength)

The standard classifies steel grades based on mechanical properties and formability:

Grade	Full Name / Description	Application
SGCC	Structural Grade Cold-rolled Commercial Quality	General forming, widely used in building panels, purlins, and appliance housings
SGCD1, SGCD2, SGCD3	Structural Grade Cold-rolled Deep-drawing Quality	Improved deep-drawing performance; higher ductility (SGCD3 > SGCD2 > SGCD1)
SGC440	Structural Grade with min. yield strength of 440 MPa	High-strength applications
SGC490	Min. yield strength: 490 MPa	Light structural members
SGC570	Min. yield strength: 570 MPa	Heavy-duty structures, purlins, roof trusses
SGC780	Min. yield strength: 780 MPa	Ultra-high strength components, reinforcement parts

Note: "SGC" = Structural Grade Cold-rolled; numbers indicate minimum yield strength in MPa.

Zinc Coating Mass (Coating Designations)

Zinc coating is specified by total coating mass per unit area (g/m²) on both sides. Common coating classes:

Coating Symbol	Total Coating Mass (g/m²)	Typical Use
Z3	30	Indoor or short-term exposure
Z6	60	--
Z8	85	Appliance, indoor panels
Z12	120	General industrial use
Z18	180	Building cladding, moderate corrosion environments
Z27	275	Heavy-duty outdoor use (e.g., roofing, marine zones)
Z35	350	Severe environments (coastal, industrial)

✅ Example: SGCC-Z27 means "Commercial quality galvanized steel with 275 g/m² total zinc coating".

Base Steel Types

Cold-Rolled (CR) Base: Smooth surface, high dimensional accuracy, suitable for painting and precision parts.

Hot-Rolled (HR) Pickled Base: Thicker gauges (typically ≥2.0 mm), used for structural sections like purlins and brackets.

Dimensional Range & Tolerances

Thickness Range: 0.4 mm to 5.0 mm

Width Range: 600 mm to 1850 mm

Length: Supplied in coils or cut lengths

Tolerances:

Thickness: In accordance with JIS G 3192 (for cold-rolled) or JIS G 3193 (for hot-rolled)

Flatness: Specified limits based on thickness and width

Edge straightness and camber also controlled

Mechanical Properties (Typical Values)

Grade	Yield Strength (Rp0.2, MPa)	Tensile Strength (Rm, MPa)	Elongation A50mm (%)	Coating
SGCC	≥280	340–500	≥20	Z12–Z27
SGCD2	≥260	320–450	≥26	Z12–Z27
SGC440	≥440	≥490	≥14	Z18–Z27
SGC570	≥570	≥610	≥12	Z27–Z35
SGC780	≥780	≥800	≥8	Z27–Z35

⚠️ Values may vary slightly depending on thickness and manufacturer.

Surface Finish & Treatments

Spangle Type:

Regular Spangle – Visible zinc crystallization

Minimized Spangle (M) – Reduced crystal size

Zero Spangle (Z) – Uniform appearance, ideal for painting or prepainted (PPGI) applications

Surface Quality:

FC: Commercial quality

FD: Superior quality

FE: Highest quality (defect-free, suitable for exposed surfaces)

Chemical Treatment:

Chromate Treatment: Improves anti-rust and paint adhesion (less common due to RoHS)

Non-Chromate (RoHS Compliant): Environmentally friendly passivation

Oiling: Light oil coating to prevent white rust during transport

Main Applications

Application	Common Grade	Typical Coating
C/Z Purlins	SGCC, SGC570	Z18–Z27
Roofing & Wall Cladding	SGCC	Z18–Z27
Pre-Painted Galvanized Iron (PPGI)	SGCC (Zero Spangle)	Z18–Z27
Appliance Housings	SGCC, SGCD	Z8–Z18
Automotive Parts	SGCD2, SGC440	Z12–Z18
High-Strength Structures	SGC570, SGC780	Z27–Z35

Equivalent Standards (International Cross-Reference)

JIS G 3302	China	Europe	United States
SGCC	DX51D+Z, Q235B-Z	S280GD	ASTM A653 SS Grade 33
SGCD2	DC03+Z	DD12+Z	ASTM A653 CS Type B
SGC570	S550GD, Q355B-Z	S550GD	ASTM A653 HSLA 50
Z275 coating	Z275 g/m²	Z275	G90 (≈275 g/m²)

Note: G90 ≈ 275 g/m² (US coating designation in oz/ft²)

Summary

JIS G 3302:2018 is a widely recognized Japanese standard for continuously hot-dip galvanized steel sheet, offering:

Clear classification by strength and formability (SGCC, SGCD, SGCxxx)

Defined zinc coating masses (Z3 to Z35)

High compatibility with international standards

Broad applicability in construction, industrial, and consumer goods

It is frequently specified in export projects to Japan, Southeast Asia, and Oceania, and often requires Mill Test Certificate (MTC) with compliance to coating, mechanical properties, and chemical composition.