1.What are the differences in the standard systems?
SGCC: Belongs to the Japanese Industrial Standard (JIS G 3302). This standard is very common in Japan, China (where it is widely adopted), South Korea, and Southeast Asia, which is influenced by Japanese standards.
S stands for Steel, G stands for Galvanized, the first C stands for Commercial/Common, and the second C stands for Cold-Rolled. Therefore, SGCC stands for "Commercial General-Grade Hot-Dip Galvanized Steel Sheet with Cold-Rolled Base."
DX51D: Belongs to the European Standard (EN 10346:2015). This standard is widely used in Europe, the Middle East, Africa, and a growing number of countries and projects adopting the European standard.
D stands for Designation, X stands for Cold-Rolled Base, 51 stands for the minimum yield strength requirement (≈140 MPa), and D stands for the surface quality grade (normal surface, suitable for most forming processes). Therefore, DX51D stands for "Hot-Dip Galvanized Steel Sheet with Cold-Rolled Base, a minimum yield strength of approximately 140 MPa, and normal surface quality."
2.What are the differences in core performance focus?
SGCC (JIS G 3302):
Main focus: Coating weight (zinc layer thickness) and surface quality. The JIS standard has very detailed coating weight grading (e.g., Z12, Z18, Z22, Z27, etc., where the number represents the minimum total coating weight (g/m²) on both sides), making this a critical parameter when selecting a material.
Relatively basic mechanical property requirements: JIS G 3302 has relatively broad and basic requirements for SGCC's mechanical properties (such as tensile strength, yield strength, and elongation), placing greater emphasis on "versatility." It generally meets general processing and structural requirements, but may not be the best choice for applications requiring extremely high formability, such as deep drawing (for which higher-grade grades such as SGCD are available).
DX51D (EN 10346):
Main focus: Formability and mechanical property level. The core of the European standard EN 10346 is the classification of galvanized steel sheets based on their difficulty in forming (D stands for formability, with higher numbers indicating better formability, e.g., DX51D < DX52D < DX53D < DX54D).
Clear mechanical property requirements: There are clear minimum requirements for yield strength, tensile strength, elongation, etc. (although the requirements for DX51D are also basic).
Coating weight: Coating weight is also an important parameter, but its representation (e.g., Z100, Z140, Z200, Z275, etc., where the number represents the minimum coating weight per side in g/m²) and grading logic differ from JIS. The European standard emphasizes the combination of coating code and substrate performance.
3.What are the differences in surface treatment status markings?
SGCC:
The surface treatment is typically indicated by a code after the grade:
SGCC (no suffix): Typically refers to conventional chromate passivation (fingerprint-resistant or lightly oiled), the most common.
SGCC A: Indicates untreated (As Coated), meaning oiled only, not passivated.
SGCC B: Phosphated.
SGCC C: Oiled and chemically treated.
SGCC D: Untreated and unoiled.
DX51D:
The surface treatment is a separate designation from the grade:
+A: Untreated (As Coated).
+C: Chromated.
+S: Oiled.
+CS: Chromated and oiled - the most common.
+M: Phosphated.
4.What are the differences in how coating weight is expressed?
SGCC (JIS G 3302):
Designated as Z followed by a number, where the number represents the minimum total coating weight (g/m²) on both sides. For example:
Z12: Total coating weight on both sides ≥ 120 g/m² (theoretical minimum per side is approximately 60 g/m²).
Z18: ≥ 180 g/m².
Z22: ≥ 220 g/m².
Z27: ≥ 275 g/m².
DX51D (EN 10346):
Indicated by "Z" followed by a number or "ZF" followed by a number. The number represents the minimum coating weight per side (g/m²). Z stands for pure zinc coating (Zinc), and ZF stands for zinc-iron coating (Zinc-Iron). For example:
Z100: Single-side ≥ 100 g/m².
Z140: Single-side ≥ 140 g/m².
Z200: Single-side ≥ 200 g/m².
Z275: Single-side ≥ 275 g/m² (basically corresponds to JIS Z27's double-side weight of 275 g/m²).
5.What are the selection recommendations?
If corrosion life (coating thickness) is of primary concern and the project is located in East Asia, SGCC (Specified Z Value) is a very intuitive and commonly used choice.
If some degree of forming (bending, stamping) is involved and the project is located in Europe or uses European standards, DX51D is a good starting point for basic formability. If better formability is required, DX52D, DX53D, etc. should be selected.
For most general structural, building envelope, and general cabinet applications, SGCC (such as Z27) and DX51D (such as Z275+CS) offer very similar performance and can often be substituted for each other. The key considerations are coating weight (single-sided vs. double-sided conversion) and surface treatment to ensure they meet the requirements.