1.Are there any differences in substrate chemical composition requirements?
ASTM standards have requirements for the chemical composition of galvanized substrates, while JIS standards generally do not.
2.What are the differences in plating regulations?
ASTM standards such as ASTM A123/A123M primarily determine coating weight by gravimetric methods, specifying a minimum average coating weight based on material thickness and type. JIS standards such as JIS G3302 use scales like Z12 and Z18 to express the minimum coating weight per surface (in g/m²), while JIS H8641 specifies the minimum average coating weight after processing. Furthermore, ASTM and older JIS standards often emphasize the minimum average coating weight, while some European and ISO standards focus on the minimum local coating thickness measured by magnetic methods. This results in significant differences in testing protocols and acceptance criteria.
3.What are the differences in mechanical properties?
ASTM A653/A653M standards often reference specific steel grades (e.g., SS grade 33, HSLA grade 50), specifying mechanical properties such as yield strength, tensile strength, and formability based on standards like ASTM A1008/A1008M. JIS G3302 defines the mechanical properties of steel grades like SGCC (commercial quality). However, for structural galvanized steel coils used in buildings, the numerical value in the Japanese designation represents tensile strength, which differs from the yield strength numerical value in the ASTM standard. For example, to meet the yield strength requirement of Q345, the American standard requires ASTM A653M GR340, while the Japanese standard requires SGH440.
4.What are the differences in testing methods?
ASTM standards often use the Pilling-Bedworth test (loss-in-peel method) or specific bend tests (such as bending around a mandrel) to evaluate coating adhesion, and also have visual standards defining acceptable spangles and surface defects. JIS standards rarely mention methods similar to the Pilling-Bedworth test, and their adhesion and other performance testing methods may differ from ASTM standards.
5.What are the differences between ASTM and JIS standards for galvanized coils in terms of application areas?
ASTM standards tend to favor globalization, high-strength, and engineering, while JIS standards emphasize regionalization, refinement, and process adaptability. These differences in their application areas reflect the divergence of market demand and industrial systems. In actual trade, product selection often hinges on target market standards (e.g., customer specifications or mandatory engineering specifications).