ASTM A653/A653M Hot Dip Zinc Coated (Galvanized) or Zinc-Iron Alloy Coated (Galvanized) Steel Sheets

The “ASTM A653/A653M Standard Specification for Hot-Dip Zinc-Coated (Galvanized) or Zinc-Iron Alloy Coated (Galvanized) Steel Sheets” standard, developed by the American Society for Testing and Materials (ASTM), describes the requirements for hot-dip zinc-coated (galvanized) or Zinc-Iron Alloy Coated (Galvanized) steel sheets in coils and cut lengths.

These products are produced in a variety of zinc or zinc-iron alloy coating weights (masses) or coating designations, as shown in the tables provided within the standard. Product offered under this standard must comply with the applicable requirements of ASTM A924/A924M Hot-dip Coated Steel Coil, unless otherwise specified. Product is available in a variety of designations, grades, and classes within four general categories designed to meet different application requirements:

Steels with stringent chemical requirements and typical mechanical properties.
Steels with stringent chemical requirements and stringent mechanical properties.
Steels with required chemical properties and required mechanical properties obtained by solid solution or furnace hardening.

Under this standard, the material is available under various names, including commercial steel, forming steel, deep-drawing steel, extra-deep-drawing steel, structural steel, high-strength low-alloy steel, high-strength low-alloy steel with improved formability, solution-hardened steel, and bake-hardenable steel. Structural steel, high-strength low-alloy steel, solution-hardened steel, and bake-hardenable steel are available in various grades depending on their mechanical properties. The yield strength, elongation, and flexural properties of the steel must be determined. A bend test is applied to the coated sheets.

For the purposes of this standard, the following terms and definitions apply:

Oven-hardenable steel: Refers to steel sheet that provides a significant increase in yield strength when applied after a moderate heat treatment, straining or cold working, such as paint baking.
Differently Coated: Galvanized steel sheet with one coating designation specified on one surface and a significantly lighter coating designation on the other surface. The unilateral relationship of the two coating designations is as shown in the note on coating uniformity in the table.
High-strength low-alloy steel: This refers to a specific group of steel sheets obtained by using microalloying elements such as columbium (niobium), vanadium, titanium, and molybdenum, which provide better formability and weldability than those obtained with conventional carbon-manganese steels. Manufacturers use one or more of these microalloying elements to achieve the desired properties.
Minimized spangle: A surface produced on hot-dip zinc-coated steel sheet in which the grain pattern is visible to the naked eye and is typically smaller and less distinct than that seen on normal spangle. This surface is produced by one of two methods:
- Zinc crystal growth began but was stopped by special manufacturing practices during the solidification of the zinc.
- Zinc crystal growth was inhibited by a combination of plating bath chemistry and cooling during solidification of the zinc.
Regular spangle: A surface produced on hot-dip zinc-coated steel sheet in which the zinc crystal structure is visible to the naked eye. The solidification of the zinc coating is generally uncontrolled, producing the variable grain size associated with this surface and is not subject to size limitations.
Solid solution-hardened steel, or solution-hardened steel: Steel sheet strengthened by the addition of substitutional alloying elements such as manganese, phosphorus, or silicon. These alloying elements can occupy the same positions as iron atoms within the steel's crystal structure. The strengthening results from a mismatch between the atomic sizes of these elements and those of iron.
Spangle-free: A smooth surface composed of small, equiaxed grains produced on hot-dip zinc-coated steel sheet, where the visual spangle pattern is difficult to discern with the naked eye, particularly the surface changes caused by spangle formation. This surface is produced by inhibiting zinc crystal growth during zinc solidification by the plating bath chemistry or cooling, or a combination of both.
Zinc-iron alloy: This is a dull gray coating, devoid of any flaking pattern, produced on hot-dip zinc-coated steel sheet. The zinc-iron alloy coating consists entirely of intermetallic alloys. It is typically produced by thermally treating hot-dip zinc-coated steel sheet after it has been removed from a molten zinc bath. This type of coating is suitable for immediate painting without requiring any further processing other than regular cleaning. The alloy coating's lack of ductility creates risks such as dusting.

In this standard, materials are classified as follows:

Commercial steel (CS types A, B and C)
Forming steel (FS type A and B)
Deep drawing steel (DDS type A and C)
Extra deep drawing steel (EDDS)
Structural steel (SS)
High strength low alloy steel (HSLAS)
High strength low alloy steel with improved formability (HSLAS-F)
Solution hardened steel (SHS)
Bake hardenable steel (BHS)

Structural steel, high-strength low-alloy steel, solution-hardened steel, and bake-hardenable steel are available in various grades based on mechanical properties. Structural steel grade 50 is available in four grades based on tensile strength. Structural steel grade 80 is available in three grades based on chemistry.

The material is available with a zinc coating or a zinc-alloy coating in various coating weights (mass) or coating designations as shown in the tables provided in the standard. The material is available with the same or different coating designations on each surface.

In short, ASTM A653/A653M is a widely accepted standard developed for hot-dip zinc-coated (galvanized) or zinc-iron alloy-coated (galvannealed) steel sheets. This standard applies to steel sheet products coated with a protective zinc or zinc-iron layer to inhibit corrosion and increase durability, making them suitable for a wide variety of industrial, construction, and automotive applications.

Sheets covered by this standard are produced in various grades and coating weights depending on the mechanical properties and corrosion resistance required for the end use.

This standard states:

Basic metal properties, including steel type and grade.
Coating types such as pure zinc and zinc-iron alloy.
Coating weights G30, G60, G90 and similarly named, corresponding to the coating mass per unit area.
Mechanical properties such as yield strength, tensile strength, elongation and hardness.

This standard specifies various test procedures to ensure compliance with the standard:

Tensile testing for mechanical properties.
Bending test for ductility and forming abilities.
Coating weight tests are generally conducted using the triple point or single point test method.
Coating adhesion through peel or bend tests to verify the durability of the coating.

Typical applications include:

HVAC duct systems and equipment enclosures.
Automotive body panels and chassis parts.
Roof, wall panels, framing and other building products.
Appliances and electrical enclosures.
Agricultural and industrial equipment.

Our organization, which has been supporting businesses across all sectors for years through a wide range of testing, measurement, analysis, and evaluation activities, boasts a strong team of employees who closely follow global developments in science and technology and are constantly improving themselves. In this context, we also provide testing services in accordance with the "ASTM A653/A653M Standard Specification for Hot-Dip Zinc-Coated (Galvanized) or Zinc-Iron Alloy Coated (Galvanized) Steel Sheets."