Definition
This specification covers the general requirements for steel sheets in coils and cut length, metallic-coated on continuous lines by the hot-dip process.
This material is intended for applications requiring corrosion resistance. Hot-dip metallic coatings are available in six different types: zinc and zinc-iron alloy, lead-tin alloy, aluminum, aluminum-zinc alloy, zinc-aluminum alloy, and zinc-aluminum-magnesium alloy.
This specification covers the general requirements that, unless otherwise specified in the product specification, apply to steel sheet in coils and cut lengths, metallic-coated on continuous lines by the hot-dip process.
The product is intended for applications requiring corrosion resistance. The product specifications contain requirements for specific strength levels, heat resistance, paintability, or formability, or a combination thereof.
ASTM A924 PDF Free Download
Chemical Composition
| TABLE 1 Product Analysis Tolerances | |||
|---|---|---|---|
| Element | Limited or Maximum of Specifified Element, % | Tolerance | |
| Under Minimum Limit | Over Maximum Limit |
||
| Carbon | To 0.15, incl | 0.02 | 0.03 |
| Over 0.15 to 0.40, incl | 0.03 | 0.04 | |
| Over 0.40 to 0.80, inc | 0.03 | 0.05 | |
| Manganese | To 0.60, incl | 0.03 | 0.03 |
| Over 0.60 to 1.15, incl | 0.04 | 0.04 | |
| Over 1.15 to 1.65, incl | 0.05 | 0.05 | |
| Phosphorus | ... | ... | 0.01 |
| Sulfur | ... | ... | 0.01 |
| Silicon | To 0.30, incl | 0.02 | 0.03 |
| Over 0.30 to 0.60 | 0.05 | 0.05 | |
| Copper | ... | 0.02 | ... |
| Titanium | To 0.10, incl | 0.01A | 0.01 |
| Vanadium | To 0.10, incl | 0.01A | 0.01 |
| Over 0.10 to 0.25, incl | 0.02 | 0.02 | |
| Columbium | Minimum only specifified | 0.01 | ... |
| To 0.10, incl | 0.01A | 0.01 | |
| "A"If the minimum of the range is 0.01 %, the under tolerance is 0.005 %. | |||
The chemical composition requirements of the base steel are shown in the individual product specifications.
An analysis of each heat shall be made by the manufacturer to determine the percentage of carbon, manganese, phosphorus, sulfur, and any other elements specified or restricted by the individual product specification.
When desired, product analysis shall be made by the purchaser on the finished product. The product analysis so determined shall meet the tolerances shown in the table.
Capped or rimmed steels are not technologically suited to product analysis due to the nonuniform character of their chemical composition, and therefore, the tolerances in
Table 1 does not apply. Product analysis is appropriate on these steels only when misapplication is apparent.
Product analysis for phosphorus or sulfur is not technologically appropriate because of the segregation of these elements in non-skilled steels. Product analysis is appropriate only when misapplication is apparent.
Samples for product analysis shall be drillings through areas stripped free of coating. At least three pieces shall be selected, but if the product of more than one mill lift or coil is involved, at least six pieces shall be selected.
When supplying High-Strength Low-Alloy Steel (HSLA), some producers use one or more microalloying elements as strengthening agents or use alloy additions to effect inclusion control or both. The producer shall be consulted for the specific chemical composition applied. If any alloying addition is known to be of concern to the user, the producer shall be notified of this concern.
Method of Analysis—The determination of chemical composition is permitted to be made by any test method, except in case of dispute, where the referee test methods listed in the section on test methods of Test Methods A 751 shall be used.
Coating:
Coating Analysis—The nominal composition of the coating is described in the individual product specification.
Method of Analysis—The determination of chemical composition shall be made in accordance with acceptable chemical, spectrochemical, or other test methods.
Thickness Tolerance ASTM A924
| Thickness Tolerance ASTM A924 (3/8 Inch Minimum Edge Distance) | ||||||
|---|---|---|---|---|---|---|
| Unit: Inch. Plus and minus for specified thickness (including base metal and coating) | ||||||
| Width/Thickness | through 0.023 | Over 0.023 through 0.043 | Over 0.043 through 0.061 | Over 0.061 through 0.075 | Over 0.075 through 0.101 | over 0.101 through 0.187 |
| To 32 incl. | 0.003 | 0.004 | 0.005 | 0.006 | 0.007 | 0.008 |
| Over 32 to 40 incl. | 0.003 | 0.004 | 0.005 | 0.006 | 0.008 | 0.008 |
| Over 40 to 60 incl. | 0.003 | 0.004 | 0.005 | 0.006 | 0.008 | 0.009 |
| Over 60 72 incl. | - | 0.004 | 0.005 | 0.006 | 0.009 | 0.009 |
Length Tolerances ASTM A924
| Length Tolerances ASTM A924 | |
|---|---|
| Unit: Inch. Tolerance over specified length. No minus tolerance. | |
| Length | Tolerance |
| Over 12 through 30 | 1/8 |
| Over 30 through 60 | 1/4 |
| Over 60 through 96 | 1/2 |
| Over 96 through 120 | 3/4 |
| Over 120 through 156 | 1 |
| Over 156 through 192 | 1.25 |
| Over 192 through 240 | 1.5 |
| Over 240 | 1.75 |
Width Tolerances ASTM A924
| Width Tolerances ASTM A924 | |
|---|---|
| Unit: Inch. Tolerance over specified width. No minus tolerance | |
| Width | Tolerance |
| Over 12 through 30 | 1/8 |
| Over 30 through 48 | 3/16 |
| Over 48 through 60 | 1/4 |
| Over 60 through 72 | 5/16 |
